The species examined in this section are Federally-listed threatened and endangered species that occur in Duval, Clay, St. Johns, Putnam, Flagler and Volusia Counties in the LSJRB (USFWS 2019a). These animals are protected under the Endangered Species Act of 1973 (Congress 1973). The West Indian manatee, bald eagle, and wood stork discussed here are considered primary indicators of ecosystem health because of their direct use of the St. Johns River ecosystem. The data available for these species were relatively more robust than data on the also listed shortnose sturgeon, piping plover, Florida scrub-jay, and Eastern indigo snake (although included in past reports, the latter three have not be included in this report). In addition, other endangered or threatened species of interest to the area include the North Atlantic Right Whale and Loggerhead Sea Turtle. However, because these animals are associated with the coastal and offshore boundaries of the LSJRB, they are not discussed in this report. All these examples convey in part the diverse nature of endangered wildlife affected by human activities in the LSJRB. These species, and many more, add to the overall diversity and quality of life we enjoy and strive to protect and conserve for the future. It is important to be aware that human actions within the LSJRB affect the health of the entire ecosystem, and that the St. Johns River is a critical component of this system. Research, education and public awareness are key steps to understanding the implications of our actions towards the environment. The list of species examined here does not include all species protected under Florida State (131 species within the state) and federal laws (15 species within LSJRB) (see Appendix 4.4.1). It is likely that in the future this list will need to be periodically updated as changes occur over time or indicator species and data are identified. For additional supporting information, the reader is asked to refer to the appendices section of the report.
4.4.1. The Florida Manatee (reclassified 2016, current status: Threatened)
In 1967, under a law that preceded the Endangered Species Act of 1973 the manatee was listed as an endangered species (Udall 1967). Manatees are also protected at the Federal level under the Marine Mammal Protection Act of 1972 (Congress 1972), and by the State under the Florida Manatee Sanctuary Act of 1978 (FWC 1978). More recently, because manatees are no longer considered to be in imminent danger of extinction, the U.S. Fish and Wildlife Service announced that the West Indian manatee was reclassified from endangered to threatened status on March 30, 2016. This action does not affect federal protections currently enforced under the Endangered Species Act (USFWS 2019a).
The Florida manatee (Trichechus manatus latirostris) is a large aquatic mammal that inhabits the waters of the St. Johns River year round and may reach a length of 12 ft and a weight of 3,000 lbs (Udall 1967; USFWS 2001). They are generally gray to dark-brown in color; have a seal-like body tapering to a flat, paddle-shaped tail. Two small forelimbs on the upper body have three to four nails on each end. The head is wrinkled and the face has large prehensile lips with stiff whiskers surrounding the nasal cavity flaps. They are not often observed during winter (December-February) being generally most abundant in the St. Johns River from late April through August. Because of their herbivorous nature all are found in relatively shallow waters where sunlight can penetrate and stimulate plant growth. Manatees do not form permanent pair bonds. During breeding, a single female, or cow, will be followed by a group of a dozen or more males, or bulls, forming a mating group. Manatees appear to breed at random during this time. Although breeding and birth may occur at any time during the year, there appears to be a slight spring calving peak. Manatees usually bear one calf, although twins have been recorded. Intervals between births range from three to five years (JU 2019). In 1989, Florida’s Governor and Cabinet identified 13 “key” counties experiencing excessive watercraft-related mortality of manatees and mandated that these counties develop a Manatee Protection Plan (MPP). The following counties have state-approved MPPs: Brevard, Broward, Citrus, Collier, Dade, Duval, Indian River, Lee, Martin, Palm Beach, Sarasota, St. Lucie, and Volusia (FWC 2014b). In 2006, although not one of the original 13 “key” counties, Clay County also voluntarily developed a State-approved MPP. St. Johns County also voluntarily developed a manatee plan, but it is has not been approved by State or Federal agencies. Putnam County does not have a MPP, whereas Flagler County is in the process of developing one. The fourth revision to the Duval County MPP was adopted by the Jacksonville City Council on February 13th 2018 (COJ 2019a).
Jacksonville University has conducted some 762 aerial surveys with over 18,413 manatee sightings (1994-2018). These surveys covered the shorelines of the St. Johns River, its tributaries (Jacksonville to Black Creek), and the Atlantic Intracoastal Waterway (Nassau Sound to Palm Valley). During the winter, industrial warm water sources were also monitored for manatee presence (aerial and ground surveys). It was observed that when water temperatures decrease (December through March); the majority of manatees in the LSJRB migrate to warmer South Florida waters (White and Pinto 2014).
Within the St. Johns River, survey data indicate that manatees feed, rest and mate in greater numbers south of the Fuller Warren Bridge where their food supply is greatest relative to other areas in Duval County. Sightings in remaining waters have consisted mostly of manatees traveling or resting. Manatees appear to use the Intracoastal Waterway as a travel corridor during their seasonal (north/south) migrations along the east coast of Florida. Data indicate that manatees stay close to the shore, utilizing small tributaries for feeding when in these waters (White et al. 2002). Aerial surveys of manatees, by various organizations and individuals, in northeast Florida have occurred prior to 1994 and are listed in Ackerman 1995.
There are two sub-populations of manatees that use the LSJRB. The first sub-population consists of about 558 manatees from the Blue Springs area (Hartley 2019), of which numbers visiting the LSJRB are not known (Ross 2019). Most of the animals in the LSJRB, about 260+ manatees (White and Pinto 2006b; White and Pinto 2006a) are members of the greater Atlantic region sub-population, with 2,394 animals in 2019 along the entire east coast of Florida, and 3,339 along the west coast for a total of 5,733 manatees (FWRI 2019e). State synoptic surveys were not conducted in some years (1993, 1994, 2008, 2012, and 2013) because weather conditions were not preferable. The warm winters meant that manatees did not aggregate well at warm water sources for counting. The Florida counts have grown significantly over time as the population has increased from an average of 1,530 manatees in the early 1990’s to 2,376 manatees (1995-2007), 4,635 manatees (2009-2015), and more recently 6,159 manatees (2014-2019). Considerable coordination and effort by FWRI are involved, for example in 2011, 21 observers from 10 organizations counted 2,432 manatees on Florida’s east coast and 2,402 on the west coast for a sum total of 4,834 (Figure 4.7). In general, few animals tend to be seen in the LSJRB because of the cold weather; although, some animals are found at artificial warm water sources. No animals were observed in the northeast Florida synoptic survey area in 2011, 2015, 2016, and 2018. However, in 2010 and 2014, two animals were observed. In 2017, the previous synoptic record count was surpassed with 3,488 animals on the east coast and 3,132 on the west coast of Florida, for a total of 6,620 manatees (on this occasion, 6 animals were observed in the northeast synoptic survey area (FWRI 2019e).
“Synoptic” can be defined as a general statewide view of the number of manatees in Florida. The FWC uses these surveys to obtain a general count of manatees statewide by coordinating an interagency team that conducts the synoptic surveys from one to three times each year (weather permitting). The synoptic surveys are conducted in winter and cover all of the known wintering habitats of manatees in Florida. The survey is conducted to meet Florida state statute 370.12 (4), which requires an annual, impartial, scientific benchmark census of the manatee population. From 1991 through 2018, the counts have been conducted 33 times (FWRI 2019e).
The weather conditions in 2010 were the coldest for the longest duration in Florida metrological history. Consequently, manatees were more concentrated at warm water sources throughout the state resulting in the second highest count ever recorded at that time with 2,780 animals on the east coast, and 2,296 animals on the west coast for a sum total of 5,076 animals (FWRI 2018b).
It should be noted that because of differences in the ability to conduct accurate aerial surveys the synoptic results cannot be used to assess population trends. For more information, see Appendix 4.4.1.A Synoptic Counts. This information is based on the results of long-term radio tracking and photo-identification studies (Beck and Reid 1998; Reid et al. 1995). Deutsch et al. 2003 reported that the LSJR south of Jacksonville was an important area visited by 18 tagged manatees that were part of a 12-year study of 78 radio-tagged and tracked manatees from 1986 to 1998. Satellite telemetry data support the fact that most animals come into the LSJRB as a result of south Florida east coast animals migrating north/south each year (Deutsch et al. 2000). Scar pattern identification suggests that significant numbers of manatees are part of the Atlantic sub-population. Since 2000, a total of 7 animals: 4 recovered in Duval County (2006, 2008, 2010, and 2012); 2 from Clay County (2011, and 2013); and 1 from St. Johns County (2010), were recovered in the northeast Florida area, that were identified as animals that came from the Blue Springs sub-population (Beck 2018). Hostetler et al. 2018 estimated that the average number of manatees in Florida in 2015–2016 was 8,810 (range 7,520-10,280).
The St. Johns River provides habitat for the manatee along with supporting tremendous recreational and industrial vessel usage that threatens them. From 2000 to 2018, pleasure boats have increased the most and represent about 97% of all vessels. St. Johns, Clay, and Flagler Counties experienced an increasing trend in the number of vessels. Duval and Putnam Counties experienced a decreasing trend in vessels. For information about each county, see Appendix 4.4.1.A Vessel Statistics. Watercraft deaths of manatees continue to be the most significant threat to survival. Boat traffic in the river is diverse and includes port facilities for large industrial and commercial shippers, commercial fishing, sport fishing and recreational activity. Florida Department of Highway Safety and Motor Vehicles (FDHSMV 2018) records show that there were 34,483 registered boaters in Duval County in 2002. This number increased to 34,494 by 2007 and has since fallen from 28,519 in 2012 to 25,546 in 2018. Duval County had the most vessels (45%) followed by St. Johns and Clay (18%), then Putnam (12%) and Flagler (7%). Port statistics indicated that 4,166 vessel passages occurred to and from the Port in 2012, and that these decreased to 3,312 in 2017 but then increased again to 3,564 in 2018 (JAXPORT 2019). In addition to this, in 2004, there were 100 cruise ship passages to and from the Port, and by 2007, this number rose to 156. In 2008 there was a decrease to 92 cruise ship passages, and then from 2009-2018 the number of passages averaged 155. Large commercial vessel calls and departures are projected to increase significantly in the future (JAXPORT 2007). Also, in order to accommodate larger ships, the JAXPORT dredged turning basins in 2008 and began to deepen the channel near the mouth of the SJR in December of 2017. Dredging can cause a change in vessel traffic patterns and increase noise in the aquatic environment that can potentially harm manatees because they cannot hear oncoming vessels (Gerstein et al. 2006). Dredging a deeper channel can also affect the salinity conditions in the estuary by causing the salt water wedge to move further upstream (Sucsy 2008), which may negatively impact biological communities like tape grass beds on which manatees rely for food (Twilley and Barko 1990).
18.104.22.168. Data Sources & Limitations
Aerial survey data collected by Jacksonville University (Duval County 1994-2019, and Clay County 2002-2003) were used in addition to historic surveys by FWC (Putnam 1994-1995). Ground survey data came from Blue Springs State Park (1970-2017). The FWRI provided manatee mortality data from 1975-2017. Other data sources include the USGS Sirenia Project’s radio and satellite tracking program, manatee photo identification catalogue, tracking work by Wildlife Trust and various books, periodicals, reports and web sites.
Aerial survey counts of manatees are considered to be conservative measures of abundance. They are conducted by slow- speed flying in a Cessna high-wing aircraft or Robinson R44 helicopter at altitudes of 500-1,000 ft. (JU 2019) and visually counting observable manatees. The survey path was the same for each survey and followed the shorelines of the St. Johns River and tributaries, about every two weeks. Throughout the year, survey time varied according to how many manatees were observed. This is because more circling is often required to adequately count them. The quality of a survey is hampered by a number of factors including weather conditions, the dark nature of the water, the sun’s glare off the water surface, the water’s surface condition, and observer bias. The units of aerial surveys presented here are the average number of manatees observed and the single highest day count of manatees per survey each year. The number of surveys each year prior to 2012 averaged 19 ± 3.5 SD (range 11-26/yr). Since then, funding for aerial surveys was significantly reduced due to budget cuts, which resulted in a lower survey frequency of 3-5 surveys/yr. This includes additional assistance with surveys from the USCG Air Auxiliary Unit. The reduced survey effort has significantly reduced the power to predict trends and represents a further limitation in the data.
The actual location that a watercraft-related mortality occurred can be difficult to determine because animals are transported by currents or injured animals continue to drift or swim for some time before being reported. In addition, the size of the vessel involved in a watercraft fatality is often difficult to determine with frequency and consistency.
Because the frequency and duration of elevated salinity events in the river can adversely affect the health of Submerged Aquatic Vegetation (SAV) on which manatee rely for food, rainfall and salinity were examined in conjunction with the number of manatees. Updated salinity data were provided by Bill Karlavige (Environmental Quality Division, City of Jacksonville). Water quality parameters are measured monthly at ten stations in the mainstem of the St. Johns River at the bottom (5.0 m), middle (3.0 m), and surface (0.5 m) depths. Data on rainfall came from the SJRWMD and NOAA (Appendix 22.214.171.124.E Rainfall, Hurricanes, and El Niño), and salinity data for specific SAV monitoring sites came from SJRWMD (Appendix 126.96.36.199.F Salinity). Regarding the salinity data associated with SAV sites and including grass beds information, these data were not available for 2012 to 2014 because that program (encompassing 152 sites) was suspended due to budget cuts. Sampling resumed on a more limited basis in 2015-2018 to include fewer stations than before (Jacksonville to Black Creek/Hallows Cove). This consisted of about 40 ground truth sites (2017) and about 80 sites (2018) when long-term monitoring sites were included with the ground truth sites.
188.8.131.52. Current Status
Aerial surveys: The average numbers of manatees observed on aerial surveys in Duval County and adjacent waters decreased prior to the drought (2000-2001) and then increased again after the drought (2000-2005). In 2005, drought conditions developed again and numbers began to decline (Figure 4.8). Since 2009, manatee numbers have begun to increase again. The longer-term trend (1994-2018) appears to be relatively stable, when excluding the variation caused by the droughts and other severe weather. Data points from 2013 to 2018 are likely to be significantly affected by reduced sampling frequency.
Single highest day counts of manatees appear to have increased to a level slightly higher than prior to the drought, but the increase is not statistically significant (2000-2005). The large dip in numbers in 1999-2000 can be attributed to the effects of the drought that caused manatees to move further south out of the Duval County survey area in search of food (Figure 4.9). A second dip in numbers (2005-2009) occurred as a result of another series of droughts. In 2010, manatee numbers began to increase again and in 2012 a high count of 177 manatees was recorded. In 2016, this was surpassed by another higher count of 192 manatees. Data points from 2013 to 2018 are likely to be significantly affected by reduced sampling frequency.
In addition, 2017 and 2018 were anomalous years, with severe drought in spring and summer of 2017, and tremendous storm activity later in September (Hurricane Irma), and the following year.
“Single highest day count” of manatees is defined as the record highest total number of manatees observed on a single aerial survey day during the year. This provides a conservative indication of the maximum number of manatees in the study area.
Ground surveys: Blue Springs is located about 40 miles south of the LSJRB within the St. Johns River system, and since this sub-population has increased over the years, we could potentially see more animals using the LSJRB in the future. The population of Blue Springs only numbered about 35 animals in 1982-83 (Kinnaird 1983a) and 88 animals in 1993-94 (Ackerman 1995). From 1990-1999, this population had an annual growth rate of about 6% (Runge et al. 2004). It is the fastest growing sub-population and accounts for about 5% of the total Florida manatee count (FWC 2007). Ground surveys indicate that the six-year average for total number of manatees seen has increased from 6% (1994-2003) to 22% (2004-2018); note also that most of these animals stay in the vicinity of Blue Springs and that calves represent about 7-8% of the total number sighted (Figure 4.10).
Total Mortality: There were a total of 786 manatee deaths in the LSJRB from 1980-2018 (Figure 4.11), of which a total of 201 were caused by watercraft (26% of total manatee deaths), 15 were from other human related causes, 129 were of a perinatal nature, 146 were from cold stress, 43 from other natural causes, and 204 were from undetermined causes. The total number of manatee mortalities (from all causes) increased towards the mouth of the SJR with Duval County being associated with 55% of all deaths, followed by St. Johns (16%), Putnam (12%), Clay (10%), and finally Flagler County with 7% (FWRI 2019d).
Manatee mortality categories defined by FWRI
|Watercraft (Propeller, Impact, Both)||Cold Stress|
|Flood Gate/Canal Lock||Natural, Other (Includes Red Tide)|
|Human, Other||Verified; Not Recovered|
|Perinatal (Natural or Undetermined)||Undetermined; Too decomposed|
Watercraft Mortality: Watercraft-related mortalities in 2018, as a percentage of the total mortality by-county, were highest in Duval (34%) followed by Putnam (19%), Clay (18%), Flagler (15%) and then St. Johns (14%). Since most deaths in the basin occurred in Duval County, watercraft deaths in Duval County were compared in five-year increments beginning 1980 through 2014. (Note that in Figure 4.11, the large drop represents just four years of data for 2015/18 and was not considered in any statistical analysis). These times were picked because they represent uniform periods either side of 1994 when the Interim Duval County MPP regulations were implemented. From 1980 to 2004, watercraft deaths of manatees in Duval County averaged 31% of total deaths, and from 2005 to 2009, watercraft deaths were 52% of total deaths. For the 5-year period from 2010 to 2014, watercraft-caused mortality decreased to 24% of total manatee mortalities in LSJRB. For the last four years from 2015 to 2018, it averaged 17% (Appendix 4.4.1.A).
In comparison, the average watercraft death rate for the state was similar for the same period 19% (± s.d. = 2.87%). Mortalities from watercraft in LSJRB showed an upward trend since the mid-1990s, with most reported in Duval County. In the last decade, watercraft deaths of manatees have decreased slightly in LSJRB. The watercraft mortality for the LSJRB was 26% of total mortality in 2018, and the state watercraft mortality rate was 15% (lower proportionally because of high numbers of red tide deaths in south Florida. In 2016, it was 28% for LSJRB and 20% for the state (FWRI 2019d).
Cold stress: When manatees experience prolonged exposure to water temperatures below 68 °F (20 °C), they can develop a condition called cold-stress syndrome, which can be fatal. Effects of cold stress may be acute, when manatees succumb rapidly to hypothermia, or longer-lasting as chronic debilitation. Chronic cold-stress syndrome is a complex disease process that involves metabolic, nutritional, and immunologic factors. Symptoms may include emaciation, skin lesions (see below on the snout) or abscesses, fat depletion, dehydration, constipation and other gastrointestinal disorders, internal abscesses, and secondary infections. The manatee in the picture below was recovering well from severe cold stress (April 2018) at the Manatee Critical Care Center, Jacksonville Zoo.
Cold-stress mortalities were particularly elevated throughout Florida during the period January to March 2010 (Figure 4.11). This period included the coldest 12-days ever recorded in the state of Florida with temperatures below 45 °F (7.2 °C) recorded in Naples and West Palm Beach. Central Florida experienced even colder temperatures. From January-April, 58 manatees were rescued and 503 manatee carcasses were verified in Florida (429 in all of 2009). Mortality was highest in the central-east and southwest regions. Florida manatees rely on warm-water refuges to survive winter and extended cold periods, which are of particular concern because the long-term survival of these animals will be dependent on access to warm water springs as power plant outfalls throughout the Florida peninsula are shut down (Laist et al. 2013). In LSJRB there were a total of 12 cold stress deaths between January 14th and February 15th 2010 – Clay (2), Duval (1), Flagler (0), Putnam (7), and St. Johns (2), compared to a total of 6 cold stress deaths in 2011 – Clay (0), Duval (3), Flagler (0), Putnam (2), and St. Johns (1) (FWRI 2012a).
The State Manatee Management Plan (FWC 2007) requires the FWC to evaluate the effectiveness of speed zone regulations. The Plan was developed as a requirement in the process, that sought to down list manatees from endangered to threatened status. Currently, manatees are considered threatened at the federal level. Taking everything into account, the current STATUS of the Florida Manatee is Satisfactory, and the TREND is Improving.
184.108.40.206. Future Outlook
Manatees in the LSJRB are likely to continue to increase as more manatees move north because of population increase, decreases in manatee habitat and its quality in south Florida. Although threats still exist, manatees do not appear to be in imminent danger of extinction. As a result, the U.S. Fish and Wildlife Service has ruled that the manatee status be upgraded to “threatened” without affecting federal protections currently enforced under the ESA (USFWS 2019b).
Recovery from the most recent drought cycle (2009-2012) should allow food resources to rebound and increase the carrying capacity of the environment to support more manatees. Current information regarding the status of the Florida manatee suggests that the population is growing in most areas of the southeastern U.S. (USFWS 2007b). In 2013, the aerial survey budget was significantly reduced to the point that useful information about population trends is more limited. In light of that issue, the USCG Auxiliary Air Unit stepped up to offer assistance in providing flights, when possible. Just like in Lee County, Florida (Semeyn et al. 2011) the manatee count and distribution information in the form of maps is discriminated to local, state and federal law enforcement, maritime industry groups, the port, and the media so that efforts can be focused on raising public awareness through education. The focus on education is primarily so that manatee deaths from watercraft can be reduced. In May of 2013, the area experienced significant rainfall and algae blooms in the mains stem of SJR near Doctors Lake. There has been a spatial shift over the last fifteen years in that fewer manatees are seen in areas north of the Buckman Bridge for extended periods of time, and more tend to congregate further south. This correlates with more suitable habitat to the south verses the north. There appears to be a decreasing trend in watercraft-caused deaths for the LSJRB from 2010-2018, though if this trend is sustained or not remains unclear (FWRI 2019d). Although there is a decreasing trend in registered vessels in Duval and Putnam Counties, significant increases in vessel traffic in the LSJRB are projected to occur over the next decade as human population increases and commercial traffic increases. More boats and more manatees could lead to more manatee deaths from watercraft because of an increased opportunity for encounters between the two. Dredging, in order to accommodate larger ships, significantly affects boat traffic patterns and noise in the aquatic environment (Gerstein et al. 2006) and has ecological effects on the environment that ultimately impact manatees and their habitat. Freshwater withdrawals, in addition to harbor deepening, will alter salinity regimes in the LSJRB; however, it is not known yet by how much. If a sufficient change in salinity regimes occurs, it is likely to cause a die-off of the grass bed food resources for the manatee. Mulamba et al. 2019 indicate that increasing salinity effects from rising sea-level are likely to be felt throughout the whole estuary. Model results indicated a hotspot in the river where salinity was predicted to increase by about 2 ppt (near river Km 30, or in-between Acosta Bridge and the Buckman Bridge (40 Km from the river mouth) (see section 2.8).
This result would decrease carrying capacity of the environment’s ability to support manatees. Some Blue Springs animals use LSJRB too, although the interchange rate is not known yet. Animals that transition through the basin are likely to be affected by the above issues. Sea level rise is another factor likely to affect the St. Johns and about which more information regarding potential impacts is needed. In addition, any repositioning of point sources can alter pollution loading to the St. Johns River and should be monitored for any potential impacts to manatees (i.e., thermal/freshwater sources), and also the grass beds on which they depend for food. Moreover, the cumulative effects of freshwater withdrawals on these and other flora and fauna should be monitored to assess the impacts of water supply policy (NRC 2011). Important monitoring programs have been reduced or eliminated due to budget cuts in the last few years. Fewer data impacts the ability of planners to gauge the effectiveness of programs that have the goal of improving environmental conditions in the river and may lead to additional costs in the future. Storms in 2017/2018 have impeded the rivers ability to bounce back ecologically. In the past, concerns were about insufficient rainfall and the frequency of droughts. More recently, too much rainfall and related effects, including flooding, have been more notable. In the future, we can expect more of these extremes that further limit the ability of nature to bounce back.
“Carrying Capacity” may be defined as the maximum weight of organisms and plants an environment can support at a given time and locality. The carrying capacity of an environment is not fixed and can alter when seasons, food supply, or other factors change.
4.4.2. Bald Eagle (delisted 2007, current status: Threatened)
The bald eagle (Haliaeetus leucocephalus) is a large raptor with a wingspan of about seven feet and represents a major recovery success story. Bald eagles were listed as endangered in most of the U.S. from 1967-1995 as a result of DDT pesticide contamination, which was determined to be responsible for causing their eggshells to be fragile and break prematurely. The use of DDT throughout the U.S. was subsequently banned, though it is still present in the environment (see Section 5.6 Pesticides). In 1995, bald eagle status was upgraded to threatened, and numbers of nesting pairs had increased from just under 500 (1960) to over 10,000 (2007).
As a result of this tremendous recovery, bald eagles were delisted June 28, 2007 (USFWS 2007a; USFWS 2008a; USFWS 2008d; AEF 2016). The eagles are found near large bodies of open water such as the St. Johns River, tributaries, and lakes, which provide food resources like fish. Nesting and roosting occurs at the tops of the highest trees (Scott 2003b; Jacksonville Zoo 2019a). Bald eagles are found in all of the United States, except Hawaii. Eagles from the northern United States and Canada migrate south to over winter while some southern bald eagles migrate slightly north for a few months to avoid excessive summer heat (AEF 2019). Wild eagles feed on fish predominantly, but also eat birds, snakes, carrion, ducks, coots, muskrats, turtles, and rabbits. Bald eagles have a life span of up to 30 years in the wild and can reach 50 years in captivity (Scott 2003b; AEF 2016; Jacksonville Zoo 2019a). Young birds are brown with white spots. After five years of age the adults have a brown-black body, white head, and tail feathers. Bald eagles can weigh from 10-14 lbs and females tend to be larger than males. They reach sexual maturity at five years, and then find a mate that they will stay with as long as they live (AEF 2019).
From 2006-2010, there was an average of 59 active nests out of a total of 107 bald eagle nests surveyed. The nests were located mainly along the edges of the St. Johns River, from which the birds derive most of their food (Appendix 4.4.2.A). Most of the nests seem to be in use about 57% of the time. Active nests represented 53% (range 47-62%) of the total nests surveyed from 2006-2008. In 2010, the number of active nests increased to 70%. Data for 2009 indicated fewer nests, because of a change in survey protocol starting November 2008 (Gipson 2014). After a hiatus of two years, bald eagle nests were surveyed again in 2013 and numbers of active nests had not changed significantly from 2010 (Gipson 2014) (Figure 4.12).
220.127.116.11. Data Sources & Limitations
Data came from a variety of sources: Audubon Society winter bird counts, FWC, Jacksonville Zoo and Gardens, USFWS and various books and web sites. No new data for the LSJRB area was available from FWCC for 2011/2013 and 2014/2015/2016/2017. Various groups conduct periodic surveys and the state has a five-year management plan (FWC 2008) to monitor the eagle’s continued welfare (FWC 2008; USFWS 2008a). Known bald eagle nesting territories within the State of Florida were surveyed by FWC during the 2009 nesting season with fixed-wing or rotary-wing aircraft beginning in late November 2008 and extending through mid-April 2009. Nest locations were determined with the use of aircraft-based GPS units. Accuracy of locations is estimated to be within 0.1 miles of the true location. In 2008, the statewide bald eagle nesting territory survey protocol changed. The protocol change reduces annual statewide survey effort and increases the amount of information gained from the nests that are visited during the survey season. Nest productivity is now determined for a sub-sample of the nests that are surveyed annually. Nest activity and productivity information are critical to determining if the goals and objectives of the Bald Eagle Management Plan are being met (FWC 2008).
18.104.22.168. Current Status
In Alaska, , there are over 35,000 bald eagles. However, in the lower 48 states of the U.S., there are now over 5,000 nesting pairs and 20,000 total birds. About 300-400 mated pairs nest every year in Florida and constitute approximately 86% of the entire southern population (Jacksonville Zoo 2019a). Statewide eagle nesting surveys have been conducted since 1973 to monitor Florida’s bald eagle population and identify their population trends. Now that this species is no longer listed as Threatened, the primary law protecting it has shifted from the Endangered Species Act to the Bald and Golden Eagle Act (AEF 2014; USFWS 2008b; USFWS 2008c). According to Jacksonville winter bird counts by the Duval Audubon Society, numbers sighted (1981-2018) have increased significantly (τ = 0.790; p=5.88E-12; n=36) since the pesticide DDT was banned in the 1960s (Figure 4.13). Taking everything into account, the current STATUS of the Bald Eagles is Satisfactory, and the TREND is Improving.
In a recent Kendall tau correlation analysis of rainfall for the LSJRB, count data for Audubon count circle in Jacksonville was negatively correlated to rainfall, but not significant (τ = -0.059; p=0.344; n=24). The analysis indicated increase in numbers of eagles over time with respect to party hours of effort (τ = 0.696; p=9.56E-07; n=24) and raw numbers (τ = 0.711; p=5.72E-07; n=24), respectively (Figures 4.14 and 4.15).
Eagle counts are expressed as numbers of birds per party hour, which accounts for variations due to the effort in sampling the birds. Each group of observers in the count circle for a day is considered one “party” and counts are conveyed together with the number of hours the observers recorded data (note this is not the number of hours of observation multiplied by the number of observers). Number of birds per party hour is defined as the average of the individual number per party hour values for each count circle in the region. In the case of no observations of a given species by a circle within the query region, a value of zero per party hour is averaged.
There was a decreasing trend in rainfall 1995-2000, which represents a prolonged period of severe drought (coincides with 1997 El Niño year). Bald eagle numbers surged as the drought deepened probably because of a concentration of their prey as water levels fell. Then, rainfall increased again from 2000-2005 with averages approaching and finally exceeding the norm by 2005. During this period, the number of eagles declined somewhat, presumably because prey resources were more spread out. Also, there was an increase in severe storms (including hurricanes, which usually have a higher potential to affect the U.S. during La Niña years) during this time period. Following 2005, another drought ensued (2005-2006), and rainfall declined at a faster rate than previously. Again, eagle numbers surged. From 2006-2009, rainfall increased toward pre-drought levels again and eagle numbers declined. Following 2009, another drought cycle began, and the eagle numbers increased abruptly. In 2010, rainfall and the number of bald eagles increased. The dip in eagle numbers in 2010/2011 may have been caused by the unusually cold weather experienced at the time. In 2012, eagle numbers remained at an all-time high with only a slight dip in 2013/2014. In 2015, there was a significant decrease in eagle numbers, but in 2016/2017, following a period of drought bald eagle numbers increased again so that the overall trend remains upward (see Appendix 22.214.171.124.E Rainfall, Hurricanes, and El Niño).
126.96.36.199. Future Outlook
Although they have a good future outlook, bald eagles are still faced with threats to their survival. Environmental protection laws, private, state, and federal conservation efforts are in effect to keep monitoring and managing these birds. Even though bald eagles have been delisted from endangered to threatened, it is imperative that everyone does their part to protect and monitor them, because they are key indicators of ecosystem health. The use of DDT pesticide is now outlawed in the U.S. Ongoing threats include harassment by people that injure and kill eagles with firearms, traps, power lines, windmills, poisons, contaminants, and habitat destruction with the latter cause being the most significant (FWC 2008; USFWS 2008a; AEF 2019).
4.4.3. Wood Stork (delisted 2014, current status: Threatened)
The wood stork (Mycteria americana) was listed as endangered in 1984 and is America’s only native stork. The reason for the Endangered Species Act (ESA) listing was declining numbers of nesting pairs from about 20,000 (1930s) to 3,000-5,000 pairs in the 1970s (Jacksonville Zoo 2019b). Wood storks originally recommended to be down listed (USFWS 2007c) were upgraded to threatened status in June 2014 (USFWS 2018). It is a large white bird with long legs and contrasting black feathers that occur in groups. Its head and neck are naked and black in color. Adult birds weight 4-7 lbs and stand 40-47 inches tall, with a wingspan in excess of 61 inches. Males and females appear identical. Their bill is long, dark and curved downwards (yellowish in juveniles). The legs are black with orange feet, which turn a bright pink in breeding adults.
Wood storks nest throughout the southeastern coastal plain from South Carolina to Florida and along the Gulf coast to Central and South America. Nesting occurs in marsh areas, wet prairies, ditches, and depressions, which are also used for foraging. They feed on mosquito fish, sailfin mollies, flagfish, and various sunfish. They also eat frogs, aquatic salamanders, snakes, crayfish, insects, and baby alligators. They find food by tactolocation (a process of locating food organisms by touch or vibrations). (USFWS 2002; Scott 2003c). Feather analysis of the banded chicks at Jacksonville Zoo suggests that the primary food sources being fed to the chicks is fresh water prey items not zoo food items or estuarine prey. Satellite tracking data to date supports this foraging pattern, with adults feeding primarily on an estuarine prey base prior to nesting, switching to fresh water prey base during chick rearing, and then return to an estuarine diet after chick fledging and during the rest of the year (Jacksonville Zoo 2019b). Nesting occurs from February to May, and the timing and success is determined primarily by water levels. Pairs require up to 450 lbs of fish during nesting season. Males collect nesting material, which the female then uses to construct the nest. Females lay from 2-5 eggs (incubation approx. 30 days). To keep eggs cool, parents shade eggs with out-stretched wings and dribble water over them. Wood storks can live up to ten years but mortality is high in the first year (USFWS 2002; Scott 2003c).
Wood stork presence and numbers can be an indication of the health of an ecosystem. The wood stork is also Florida’s most endangered species of wading bird that requires temporary wetlands (isolated shallow pools that dry up and concentrate fish for them to feed on). Scarcity of this specific habitat type due to human alteration of the land is one cause of nesting failures, as has been reported in the Everglades (Scott 2003c).
188.8.131.52. Data Sources & Limitations
Data came from Audubon Society winter bird counts from 1962-2017, USFWS surveys and Southeast U.S. Wood Stork Nesting Effort Database, FWC/FWRI collaborative work in the SJRWMD area, and Donna Bear-Hull of the Jacksonville Zoo and Gardens from 2000-2017. The Audubon winter bird count area consists of a circle with a radius of ten miles surrounding Blount Island in Jacksonville, FL. The USFWS has conducted aerial surveys, which are conservative estimates of abundance and are limited in their use for developing population estimates. However, they still remain the most cost-effective method of surveying large areas. Ground surveys on individual colonies, like at the zoo, tend to be more accurate but cost more on a regional basis (USFWS 2002).
184.108.40.206. Current Status
An increasing trend since the 1960s was indicated by the Audubon Society winter bird count data for Jacksonville (Figure 4.16 and Appendix 4.4.3.A).
Rainfall appears to affect wood stork status in several different ways. In the short term (1995-2018), rainfall for the LSJRB was negatively correlated with numbers of wood storks, but this was not significant (τ = -0.116; p=0.214; n=24) (Figure 4.17). There was a decreasing trend in rainfall 1995-2000, which represents a prolonged period of severe drought (coincident with 1997 El Niño year). Wood storks surged in numbers as the drought deepened probably because of a concentration of prey as water levels fell. Then from 2000-2002, water levels became too low to support nesting or prey, causing a decline in numbers of wood storks (Rodgers Jr et al. 2008a). Rainfall increased again from 2000-2005 with averages approaching, and finally exceeding, the norm by 2005. During this period the numbers of wood storks continued to decline because of a natural lag in population and food supply. Then, numbers increased again by 2003. Although rainfall continued to increase, numbers of wood storks fell dramatically from 2003-2005. This was probably due to increased storm activity that damaged wood stork colonies, particularly in 2004 when four hurricanes skirted Florida. Also, higher water levels may have caused depressed productivity to breeding adults by dispersing available prey (Rodgers Jr et al. 2008b). Another drought ensued from 2005-2006 and rainfall declined at a faster rate than previously. As before, stork numbers began to increase initially. Then, from 2006-2009, rainfall continued to increase, and wood stork numbers declined. In 2010, following a prolonged cold winter, another cycle of drought began, and wood storks began to increase. Rainfall in the last few years increased close to normal levels again for the area and the wood stork population rebounded. However, in 2016 and early 2017, there was a severe drought which caused a large increase in wood storks. Then in late 2017, numbers fell sharply probably due to storm impacts to wood stork colonies from Hurricane Irma, and subsequent storms in 2017/2018, including Hurricane Michael in October 2018 (see Appendix 220.127.116.11.E Rainfall, Hurricanes, and El Niño). Taking everything into account, the current STATUS of the Wood Storks is Satisfactory, and the TREND is Improving.
Rainfall data for LSJRB (1995-2018) was negatively correlated with Wood storks when party hours of effort were considered, (τ =-0.245; p=0.05; n=24) (Figure 4.17).
Brooks and Dean 2008 describe increasing wood stork colonies in northeast Florida as somewhat stable in terms of numbers of nesting pairs (Appendix 4.4.3.A). A press release by the USFWS (Hankla 2007) stated that the data indicate that the wood stork population as a whole is expanding its range and adapting to habitat changes and for the first time since the 1960s, that there had been more than 10,000 nesting pairs. For a map of the distribution of wood stork colonies and current breeding range in the southeastern U.S., see Figure 4.18.
Rodgers Jr et al. 2008b made a comparison of wood stork productivity across colonies from different regions of Florida. Northern colonies in Florida exhibited greater productivity than those at more southerly latitudes. However, fledgling success was highly variable by year and colony. Local weather conditions and food resources were particularly important in determining nesting and fledgling success. Rainfall during the previous 12-24 months had a significant effect on fledging rates, as did both wetland and non-wetland habitats on fledging rate and colony size (Rodgers Jr et al. 2010).
In the LSJRB, there are several colonies of interest, three of these include: (1) Jacksonville Zoo and Gardens: This colony was formed in 1999 and has continued to persist strongly with growth leveling off from 2010 to 2016. In 2017 and 2018, there was a significant decline due to nest damage from storms. The Zoo group continues to have the highest number and productivity of birds in central and north Florida (Rodgers Jr et al. 2008a) (Figures 4.19 and 4.20; Appendix 4.4.3.B). It is considered one of the most important rookeries in Duval County (Brooks 2019). Donna Bear-Hull from the Jacksonville Zoo reported that the 4th year colony doubled in size from 40 breeding pairs (111 fledged chicks) in 2002 to 84 pairs (191 fledged chicks) in 2003. Since 2003, the colony’s growth rate has slowed due to space limitations. Local adverse weather conditions (drought) that had an impact on the population and its food supply prevailed in 2005. As food supply was probably concentrated as water levels fell, the colony continued to grow, reaching a high of 117 pairs (267 fledged chicks) in 2006. Then in 2007 a crash occurred and numbers of pairs declined to 47 (58 fledged chicks) following Hurricane Ernesto (August 24-September 1, 2006). In 2008, there was a rebound with the population almost doubling from the previous year to 86 pairs (181 fledged chicks) (USFWS 2004; Bear-Hull 2019). In 2009, the nesting and fledgling rates were similar 88 pairs, but 124 fledged chicks (USFWS 2019c). In 2010, the number of wood storks increased to 107 pairs and 276 fledged chicks following drought conditions. From 2011 to 2013, there was a significant decline in the numbers of fledglings to a low of 35 fledglings from 90 pairs in 2013, again after increased storm frequency. From 2010 to 2016 the population was close to carrying capacity and with stabilizing numbers of nests and reasonably consistent nest success rates (2016: 101 nests, 78% success rate; 2015: 91 nests, 81% success rate; 2014: 88 nests, 74% success rate; 2013: 90 nests, 30% success rate; 2012: 106 nests, 76% success rate). Severe drought and storms in 2017 (70 nests, 81% success rate) and 2018 (45 nests, 76% success rate) caused a significant decrease in nests and fledglings, although nest success rates were relatively unchanged (Bear-Hull 2019).
In 2003, the zoo formed a conservation partnership with USFWS to monitor the birds/nests more closely (twice weekly). Since that time, the zoo has banded 11 chicks (of 1,060 fledglings) and 9 adults. In addition, four adults have been fitted with satellite monitoring tags. The 9 banded adults returned every year to the zoo site until 2007, some did not perhaps going to other rookeries. Satellite tracking data to date supports this foraging pattern, with adults feeding primarily on an estuarine prey base prior to nesting, switching to fresh water prey base during chick rearing, and then return to an estuarine diet after chick fledging and during the rest of the year (Jacksonville Zoo 2019b).
A success is defined as at least one successful hatch. The mean success rate of nests at the zoo increased from 90% (2009) to 98% (2010); then decreased to 72% (2012), and further to 31% (2013), but then increased again to 74% (2014), 81% (2015), 78% (2016), 81% (2017), and 76% (2018).
(2) Dee Dot Colony: In 2005, the USFWS reported that there were over a hundred nests in this cypress swamp impounded lake in Duval County. However, the fledgling rate was low (1.51 chicks/nest in 2003, and 1.42 chicks/nest in 2004). Fledgling rates greater than two chicks/nest/year are considered acceptable productivity (USFWS 2005). Furthermore, the number of nests decreased from 118 in 2003 to 11 in 2007. This decline was probably due to nesting failure in 2003 caused by winds greater than about 20 mph and rain in excess of 1.5 inches/hr) (Rodgers Jr et al. 2008b; Rodgers Jr et al. 2008a). Fledgling rate improved from an average of 1.75 chicks/nest/year (2003-2005) to 2.11 chicks/nest/year in 2006 (USFWS 2007c). The rate then declined to 1.45 (2007) and rose back to 2.07 (2008) (Rodgers Jr et al. 2008b; Rodgers Jr et al. 2008a). Rainfall continued an upward trend; although the colony was active (determined by aerial survey), data on wood storks numbers were unavailable for the years 2010, 2012, and 2013 (Figures 4.21 and 4.22). In 2014, the colony consisted of 170 active wood stork nests, determined from aerial photographs, and in 2015, there were in excess of 130 nests. In 2016, 100 nest were reported with 28 successes and 81 chicks fledged (2.85 chicks/nest). Increased storm activity in 2017 likely led to a significant decrease in nests, totaling 43, and a low fledgling rate of 1.03 chicks/nest (Bear-Hull 2019; USFWS 2019c).
(3) Pumpkin Hill Creek Preserve State Park: This colony in Duval County had 42 nests in 2005 and 2008 (down from 68 in 2003) and fledgling rate averaged 1.44 chicks/nest/year in those years (USFWS 2005). Lack of rainfall during the breeding season (March to August) resulted in no water below the trees in 2004 that contributed to nest failures. Flooding following post-August 2004 hurricane season resulted in a return of breeding storks in 2005 (Rodgers Jr et al. 2008a). In 2009, the colony was described as being active, but no data were available (Brooks 2019; USFWS 2019c). The site was inactive during 2010 to 2016, and no data were available for 2017 and 2018 (Figures 4.23 and 4.24).
18.104.22.168. Future Outlook
Historically, the wood stork breeding populations were located in the Everglades but now their range has almost doubled in extent and moved further north. The birds continue to be protected under the Migratory Bird Treaty Act and state laws. Although they are not as dependent on the Everglades wetlands, wetlands in general continue to need protection. Threats continue to exist such as contamination by pesticides, harmful algae blooms, electrocution from power lines and human disturbance such as road kills. Adverse weather events like severe droughts, thunderstorms, or hurricanes also threaten the wood stork colonies. The USFWS Wood Stork Habitat Management Guidelines help to address these issues. Continued monitoring is essential for this expanding and changing population (USFWS 2007c). The U.S. Fish and Wildlife Service upgraded the status for wood storks from endangered to threatened because of the success of conservation efforts over the last 30 years (USFWS 2016).
4.4.4. Shortnose Sturgeon (Endangered)
The shortnose sturgeon (Acipenser brevirostrum) is a native species historically associated with rivers along the east coast of U.S. from Canada, south to Florida. The fish tend to be found in larger populations in more northerly rivers. The Shortnose sturgeon was listed as endangered in 1967. It is a semi-anadromous fish that swims upstream to spawn in freshwater before returning to the lower estuary, but not the sea. The species is particularly imperiled because of habitat destruction and alterations that prevent access to historical spawning grounds. The St. Johns River is dammed in the headwaters, heavily industrialized and channelized near the sea, and affected by urbanization, suburban development, agriculture, and silviculture throughout the entire basin. Initial research conducted by the National Marine Fisheries Service in the 1980s and 1990s culminated in the Shortnose Sturgeon Recovery and Management Plan of 1998 (NMFS 1998; FWRI 2019f; NOAA 2019b).
“Anadromous” fish live in the ocean, but return to freshwater to spawn.
There are no legal fisheries or by-catch allowances for shortnose sturgeon in U.S. waters. Principal threats to the survival of this species include blockage of migration pathways at dams, habitat loss, channel dredging, and pollution. Southern populations are particularly at risk due to water withdrawal from rivers and ground waters and from eutrophication (excessive nutrients) that directly degrades river water quality causing loss of habitat. Direct mortality is known to occur from getting stuck on cooling water intake screens, dredging, and incidental capture in other fisheries (NMFS 1998).
22.214.171.124. Data Sources & Limitations
Information on shortnose sturgeon in literature is limited to a few specimen capture records. Information sources included books, reports and web sites. Shortnose sturgeons have been encountered in the St. Johns River since 1949 in Big Lake George and Crescent Lake (Scott 2003a). Five shortnose sturgeons were collected in the St. Johns River during the late 1970s (Dadswell et al. 1984) and, in 1981, three sturgeons were collected and released by the FWC. All these captures occurred far south of LSJRB in an area that is heavily influenced by artesian springs with high mineral content. None of the collections was recorded from the estuarine portion of the system (NMFS 1998). From 1949-1999, only 11 specimens had been positively identified from this system. Eight of these captures occurred between 1977 and 1981. In August 2000, a cast net captured a shortnose sturgeon near Racy Point just north of Palatka. The fish carried a tag that had been attached in March 1996 by Georgia Department of Natural Resources near St. Simons Island, Georgia. During 2002/2003 an intensive sampling effort by researchers from the FWRI captured one 1.5 kg (3.3 lbs) specimen south of Federal Point, again near Palatka. As a result, FWRI considers it unlikely that any sizable population of shortnose sturgeon currently exists in the St. Johns River. In addition, the rock or gravel substrate required for successful reproduction is scarce in the St. Johns River and its tributaries. Absence of adults and marginal habitat indicate that shortnose sturgeons have not actively spawned in the system and that infrequent captures are transients from other river systems (FWRI 2019f; NOAA 2019b).
126.96.36.199. Current Status
The species is likely to be declining or almost absent in the LSJRB (FWRI 2019f). Population estimates are not available for the following river systems: Penobscot, Chesapeake Bay, Cape Fear, Winyah Bay, Santee, Cooper, Ashepoo Combahee Edisto Basin, Savannah, Satilla, St. Marys, and St. Johns River (Florida). Shortnose sturgeon stocks appear to be stable and even increasing in a few large rivers in the north but remain seriously depressed in others, particularly southern populations (Friedland and Kynard 2004).
188.8.131.52. Future Outlook
The Shortnose Sturgeon Recovery and Management Plan (NMFS 1998) identifies recovery actions to help reestablish adequate population levels for de-listing. Captive mature adults and young are being held at Federal fish hatcheries operated by the USFWS for breeding and conservation stocking.