4. Please provide reasonable assurances that the proposed project will not jeopardize the abundance and diversity of wetland-dependent wildlife and listed species and their habitats pursuant to the Environmental Criteria in Section 10.2.2, Vol. I. Please provide any correspondence received from the Florida Fish and Wildlife Conservation Commission and the U.S. Fish and Wildlife Service, and any management plans, as appropriate.

During the permitting efforts for all Federal, State and Local agencies, the environmental consultant has received no comments from FWC or USFWS regarding wetland dependent species. Lee County has requested information and that response is attached. Wading Bird Biology Influencing Dry Detention Area - Alico Lakeside

Biological Information

Description

The herons, egrets, ibises, spoonbills, and storks comprise the wading birds of Florida (GFC 1991). Although never accurately estimated, the total population of wading birds in Florida is believed to have fluctuated greatly over the years. Historically, many wading birds were hunted for their plumage, resulting in a drastic population decline in the early 1900s. Since that time, the populations rebounded, but a second drastic decline occurred, as estimated in 1970. The second population decline has been attributed to wetland alteration and destruction. Most recently, the population decline of wading birds in south Florida has been "attributed to degradation and loss of feeding habitat rather than loss of rookery habitat, hunting, or harassment" (GFC 1991).

Wood storks are discussed in a separate section of this report (federally listed species). The snowy egret (Egretta thula), the white ibis (Eudocimus albus), the roseate spoonbill (Ajaia ajaja), and two herons (Egretta caerulea and E. tricolor) are known to occur in the general areas that the proposed Phase IV project corridor traverses. These five species are listed as "species of special concern" by the GFC, the FWS does not list any of these birds.

Snowy egret (Egretta thula)

This bird is a medium-small, all white wading bird, often described as "dainty" in stature (Ogden in Rodgers. Kale and Smith 1996). The snowy egret is approximately 60 cm (24 inches) in length with a wingspan of 1 m (39 inches). The bill and legs are black, while the iris, lores, and feet are yellow. Skin color on the lores and feet changes to orange-red or red on adults during courtship. Breeding adults exhibit prominent white plumes on the head, neck, and scapulars, which are recurved and extend across the back to the tail. Plumes on non-breeding adults and immature birds are much less conspicuous or totally lacking.

White ibis (Eudocimus albus)

The white ibis is a medium-sized wading bird of approximately 56-cm total length with a 96-cm wingspan (Frederick in Rodgers, Kale and Smith 1996). The most distinct feature is the long down-curved bill. Plumage of adults is white except for the black extremities of the four longest primaries. (1n some lighting conditions the coloration of these extremities appears iridescent dark green.) The soft parts of adults are fleshy pink and become bright red before and during the short courtship period. White ibises are considerably sexually dimorphic with males up to 30% larger than females. The bill length is the most obvious difference in size between the two sexes. Post-fledgling birds have dark brown wings, neck, head, tail, and irides, white backs (evident when flying), and gray legs during their first year. Near the end of their first year, juveniles begin to acquire white plumage with sparse brown feathers remaining on their head and neck at the end of their second year. By the end of the third year, all brown has molted out.

Roseate spoonbill (Ajaiaaiaja)

The roseate spoonbill is a long-legged wading bird with a spatulate bill. It is the only spoonbill native to the Western Hemisphere (Bjork and Powell in Rodgers, Kale and Smith 1996). They stand about 80 cm (31 inches) high and have a wingspan of 1.3 m (51 inches) with a weight of 1,225 -1,800 grams. Adult plumage of birds greater than three years of age is quite variable: rose-pink on the back, wings, and lower breast; carminecolored lesser wing and upper and under tail coverts; a white neck and upper breast with a patch of stiff, curly carmine feathers at the base of the neck; yellowish wash on the breast adjacent to the bend-of-wing; an unfeathered head of pale green to golden-buff, with a line of black skin around the ears and back of head that sometimes extends as a "V" down the back of the neck; grayish-green to grayish-tan bill; and orange-buff tail. Birds that are one to 12 months of age are uniformly pale pink with fully feathered, white heads and necks and dark-tipped outer primaries. At one to three years of age, birds are intermediate in color, become bareheaded, and acquire the black line on the head at year two. Sexes are morphologically similar. Roseate spoonbills extend their necks straight forward with the legs trailing behind during flight. Flying patterns consist of wing flapping alternating with short glides, in contrast to the white ibis that has a more rapid wing beat.

Little Blue Heron (Egretta caerulea)

The little blue heron is a medium-sized ardeid approximately 64-74 cm (25-29 inches) in length with a wingspan of about 1 m (40 inches) (Rodgers in Rodgers, Kale and Smith 1996). Body measurements and plumage are similar for both sexes. The adult plumage consists of purplish-maroon head and neck with a small whitish region on the throat and upper neck. The remainder of the plumage is slate-blue with the distal third of the bill being black and the balance of the bill being pale yellow to grayish-green. The legs are grayish-green during the non-breeding season and black during the breeding season. During the breeding season, the plumes of the crest, lower neck, and the back become long lanceolate.

The immature little blue heron is mostly white with pale slate-gray tips on the primaries (Rodgers in Rodgers, Kale and Smith 1996). This feature is unique among the dark plumaged ardeids. The immature little blue heron has yellow-green legs and begins to acquire the dark plumage during their first spring, becoming "pied" or "calico." The areas of the crest, lower neck, and back are slowly replaced with dark plumage while the secondaries and primaries are replaced in symmetry. Breeding subadults attain the cobalt-blue soft-part colors on the bill and orbital skin, but the legs typically remain yellow-green. The full adult plumage is reached by the second year.

Tricolored heron (Egretta tricolor) The tricolored heron is a medium-sized heron at 65 cm (25 inches) in length with a long, slim neck, and two-toned color pattern (Ogden in Rodgers, Kale and Smith 1996). Adults have dark slate-colored heads, necks, and bodies except for a white rump, belly, and undertail coverts. The front of the neck has a white and rufous streak. Head plumes and elongated feathers on the lower neck and chest are purplish in color. The legs, feet, base of the bill, and bare facial skin are all yellow, with the bill darkening to dusky at the tip. During breeding, the adults have long, whitish head plumes and rufous to whitish mantle plumes. Soft parts also change color, with the bill and facial skin turning aquablue, the iris turning magenta, and the legs becoming orange-red.

Immature tricolored herons, up to about one year in age, are extensively reddish-brown on the head and neck, brownish on the mantle, and white in the same areas as adults. Typically, young birds lack plumes.

Distribution and Habitat

Snowy egret (EQretta thula)

Snowy egrets were extensively hunted for their plumes in the late 19`h and early 20`h centuries throughout North, Central, and South America (Ogden in Rodgers, Kale and Smith 1996). They became quite rare or were even locally extirpated in much of their range. Although no population data exists for snowy egrets outside the United States, they are believed to have recovered from the plume-hunting days and are considered to be fairly common to common in many regions of Central and South America.

The snowy egret was a common nesting species along the coast of the Gulf of Mexico, throughout Florida, and on the Atlantic coast as far north as New Jersey (Ogden in Rodgers, Kale and Smith 1996). Following the post-plume hunting days, the snowy egret rapidly recovered in most regions, even though they were extirpated or became rare in some locations during the plume-hunting era. Within Florida, the number of nesting snowy egrets has been declining since the 1950s.

Snowy egrets in Florida nest in both coastal and inland wetlands, commonly in mangroves or willows (Ogden in Rodgers, Kale and Smith 1996). Nesting also occurs in many woody species of shrubs and small trees, including Australian pine, cypress, pond apple, Brazilian pepper, buttonbush, and elderberry. Nearly all nesting occurs over shallow expanses of open water. Foraging takes place in a wide variety of permanently and seasonally flooded marshes, swamps, lake and stream shorelines, and water impoundments, even in temporarily flooded ditches and agricultural fields. Typically, the water is relatively shallow and calm. Snowy egrets also feed in upland grasslands and at the edges of the surf along beaches.

White ibis (Eudocimus albus)

White ibises are common breeding species in the coastal plain of the southeastern United States from North Carolina through Texas (Frederick in Rodgers, Kale and Smith 1996). Their range extends throughout wetland habitats of Central America and northern South America to the northern coast of Brazil. White ibises are common as breeding, migratory, and wintering birds throughout peninsular Florida and are probably Florida's most common wading bird. The breeding range of white ibises has extended northward since the 1960s when the birds began to decline in southern Florida. White ibises are known to migrate to Florida and Cuba during winter months, departing in March and April.

The white ibis has a broad tolerance for foraging and nesting habitats (Frederick in Rodgers, Kale and Smith 1996). Freshwater, brackish, and saline environments provide habitat for nesting and foraging. Adults appear to prefer foraging in freshwater habitats when feeding young. Young are not able to excrete salt through a nasal salt gland; therefore, this species must be provided access to fresh water in order to breed successfully. White ibises prefer relatively shallow water depths for feeding, though they have been observed feeding on lawns and pastures. Foraging habitats include bottomland hardwood and cypress swamps, river banks, salt marsh meadows, wet prairies, floating vegetated mats, mudflats, mangrove swamps, sawgrass strand edges, hydric hammocks, canal edges, beach flats, and landfills. The primary prey items include aquatic arthropods, especially crayfish and insects, with small amphibians and reptiles commonly consumed. White ibises will eat fish, but the fish must be extremely abundant or vulnerable for the ibis to catch them. This species is a tactile feeder like the wood stork. White ibises tend to nest in shrubby vegetation with moderate shade surrounded by water to prevent predation by terrestrial mammals. Their preference for nest building includes ground nests in clumps of grasses and in trees up to 15 m tall.

Roseate spoonbill (Aiaia ajaja)

Roseate spoonbills are residents along the Gulf coast of Texas and southwestern Louisiana, southern Florida, along both coasts of Central America, and through the Greater Antilles including Cuba, the Isle of Pines, Hispaniola, and Great Inagua (Bjork and Powell in Rodgers, Kale and Smith 1996).

Roseate spoonbills have not fully reclaimed their historic range in Florida (Bjork and Powell in Rodgers, Kale and Smith 1996). Prior to the mid-1800s, spoonbills nested as far north as Tampa Bay (Pinellas County) on the Gulf coast, Brevard County on the east coast and interior (17 Mile Swamp and Lake Poinsett), and south to the Marquesas and Boca Grande Keys. The nesting population was reduced in Florida to only one colony at Bottle Key in Florida Bay by 1935. Spoonbills recovered somewhat in subsequent years with a peak of 18 colonies in Florida Bay in 1978-1979. Following this peak, a second decline occurred in the mid-1980s, but rebounded to a new high of 20 colonies in 1984.

Nest placement is at about 2-5 m above the ground or on the surface of the water. Egg-laying occurs primarily between late March and June or as late as August in Florida. Clutch size is typically 2-5 eggs in Florida colonies, varying widely among colonies with a range of means of 2.47 to 4.13 eggs. The incubation period for snowy egrets is not accurately known, but is believed to be about the same time frame as the similar-sized tricolored heron (22-25 days) (Ogden in Rodgers, Kale and Smith 1996). Most young begin to leave the nests and venture onto adjacent branches when they are between two and three weeks of age. Many factors, such as predation, inadequate food resources, weather-related disturbance, and human disturbance, cause adults to abandon nesting attempts.

White ibis (Eudocintus albus)

White ibises are extremely gregarious and are seldom seen individually. Keeping with this habit, the species is a colonial nester, but is extremely nomadic in its nesting habits. Even the larger colonies are quite variable in size from one season to the next. White ibises probably breed for the first time during late spring at the end of their third year of life. The nest success rate varies from site to site and year to year, but rarely exceeds 80 percent. Clutch size ranges from one to four eggs with only one young raised to fledging age (Frederick in Rodgers, Kale and Smith 1996).

Roseate spoonbill (A'al is aiaja)

Roseate spoonbills are believed to first nest at three years of age; however, birds with subadult plumage have been observed nesting in Tampa Bay (Bjork and Powell in Rodgers, Kale and Smith 1996). The nesting season varies with the geographic region. In Florida Bay, nesting occurs from November to March while in peninsular Florida, nesting occurs from March to July. Spoonbills lay eggs at a rate of one egg every other day with incubation beginning on the day the first egg is laid. Clutch size in Florida Bay ranges from 2.8 to 3.7 eggs per nest. Productivity (juveniles 3-5 weeks old per nesting attempt) has been highly variable since the late 1930s with estimates ranging from complete nesting failure to 2.2 young per nest (Bjork and Powell in Rodgers, Kale and Smith 1996). Fledging occurs at about six weeks of age and the fledglings disperse from the nest at about eight weeks of age.

Mortality of roseate spoonbills has been attributed to predation by bald eagles and possibly turkey vultures, and to malnutrition and disease (Bjork and Powell in Rodgers, Kale and Smith 1996). Mercury concentrations in liver tissue of nestlings from Florida Bay colonies ranged from 0.16 to 5.38 ppm (wet weight). Such concentrations are similar to other wading bird species with concentrations being higher in eastern versus western Florida Bay birds.

Little Blue Heron (Egretta caerulea)

Little blue herons begin breeding during their first year of life at 11-12 months old, comprising approximately 2% of the nesting herons (Rodgers in Rodgers, Kale and Smith 1996). The eggs are pale blue and are laid over a period of several days at 1-2 day intervals. Incubation begins with the first egg laid and continues for 21-24 days. Reproduction success is affected by both inter-and intrayear variation. The modal clutch size is three eggs with a range of two to five. Hatching success is typically high (approximately 91%), but nestling survivorship beyond 10-14 days ranges from 50 to 84% (Rodgers in Rodgers, Kale and Smith 1996). Egg loss and nestling mortality is affected by starvation, collapse of nests, and predation. Typically, early nesting little blue herons exhibit larger clutch sizes and higher nestling survivorship.

Little blue heron young are semialtricial at birth (Rodgers in Rodgers, Kale and Smith 1996). The nestlings can stand and walk out onto branches at 10-12 days of age. The young are fully feathered and independent of the parents at 21-24 days of age. Fledging takes approximately six to seven weeks. Maximum life span is not known, but little blue herons probably reach at least 12 years of age.

Tricolored heron (EQretta tricolor)

Tricolored herons may nest in colonies that are small and comprised of only tricolored herons, or, more commonly, they nest in larger, multi-species colonies (Ogden in Rodgers Kale and Smith 1996). The larger colonies are usually located in coastal areas rather than in the interior, although relatively large freshwater colonies of tricolored heron occasionally form in the Everglades. Nesting tricolored herons are commonly associated with nesting snowy egrets.

Nests are simple, somewhat flimsy platforms of twigs constructed approximately two to five meters above ground (Ogden in Rodgers, Kale and Smith 1996). Egg laying begins in early February and peaks in early March within the Everglades National Park. Egg laying in other portions of Florida occurs between middle March and early June, and sometimes as late as August. Clutch size is usually three eggs with a range of two to five eggs. Incubation takes 22-25 days.

Nestling tricolored herons spend most of the first two weeks in the nests and are typically fed four to five times each day (Ogden in Rodgers, Kale and Smith 1996). At as early as 11 days, older chicks move out of the nests onto adjacent branches, but return to the nest for feeding until about the age of three to four weeks. After three to four weeks, but before seven to eight weeks of age, the chicks become independent of the adults. Young birds are still fed in the colony, but feeding occurs away from the nests. Nest success rates vary considerably among colonies and years. Primary causes of nest failures are nestling starvation, nest abandonment by adults, and predation.

Factors Affecting Decline

Snowy adret (Egretta thula)

As stated previously, in the early 1900s, plume hunting decimated the snowy egret population throughout its historic range (Ogden in Rodgers, Kale and Smith 1996). Since that time, the primary factor affecting population decline is habitat loss or alteration. It is believed feeding habitat loss within the last several decades in Florida is responsible for the population decline rather than colony destruction. The loss of wetlands continues to be the primary threat to the snowy egret. White ibis (Eudocimus albus)

Foraging habitat destruction and degradation (Frederick in Rodgers, Kale and Smith 1996) threaten the white ibis population. Human development on lakes, wetlands, and rivers is responsible for wetland eutrophication. Increased salinity in estuaries (e.g. Tampa Bay, Biscayne Bay, Florida Bay) is the result of increased human consumption of fresh water and lowering of the water table. Additionally, the disappearance of seasonally flooded wetlands can be directly attributed to human encroachment. Both processes contribute to the degradation of foraging habitat for white ibises. Large-scale degradation of foraging habitat is occurring in the Everglades through compartmentalization of the marsh, artificial manipulation of the normal hydrological cycle, and eutrophication of the marshes. Being primary and secondary consumers, the threat of bioaccumulation is not extreme; however, contamination with residues of pesticides, herbicides and heavy metals is a real danger, especially as wetlands are converted to agricultural lands (Frederick in Rodgers, Kale and Smith 1996).

White ibis colonies are quite vulnerable to human disturbance during courtship and egg laying (Frederick in Rodgers, Kale and Smith 1996). Ibis chicks will jump from the nest at an early age (10-18 days) with such behavior being contagious within the colony. Human disturbance during this stage can cause significant mortality of young due to their inability to regain the nest.

Roseate spoonbill (Ajaia ajaja)

Roseate spoonbills are particularly vulnerable during nesting season because they restrict their foraging activities to areas in close proximity to the colonies (Bjork and Powell in Rodgers, Kale and Smith 1996). Nesting distribution is influenced by loss of foraging habitat, as occurred in the Florida Keys during 1955 through 1985. Habitat loss occurred as a result of commercial and residential development. To a lesser degree, natural expansion of mangrove vegetation accounted for some habitat loss.

Nesting success is also influenced by intraseasonal changes in availability of foraging habitat (Bjork and Powell in Rodgers, Kale and Smith 1996). Typically, habitats experience a gradual dry-down with subsequent concentration of prey, facilitating feeding of young spoonbills. Flooding events, extreme temperatures, and drought conditions affect foraging habitat of spoonbills.

Human disturbance of nesting sites also greatly affects roseate spoonbills (Bjork and Powell in Rodgers, Kale and Smith 1996). Nesting numbers of roseate spoonbills declined dramatically on a Florida Bay island in direct correlation with increased boating activity. A 100-foot no-access-zone was posted around the island with patrolling by park rangers; nesting numbers more than doubled the following year.

Little Blue Heron (Egretta caerulea) Little blue herons were not affected directly by the plume trade of the early 1900s (Rodgers in Rodgers, Kale and Smith 1996). Human disturbance of breeding colonies may affect reproduction at sites used for recreational purposes. The primary sources of threat to little blue herons are alteration of hydrocyles of wetlands used for foraging and nesting and exposure to pesticides and heavy metal contamination. Additionally, little blue herons will forage at fish farms and hatcheries, which exposes them to illegal shooting.

Tricolored heron (Egretta tricolor)

The only apparent threat to tricolored herons is unstable and inadequate habitat options (Ogden in Rodgers, Kale and Smith 1996). No other threats, such as environmental contaminants, destruction of colony sites, or shooting, have been documented.

Literature Cited

Bjork, Robin and George V.N. Powell. 1996. Roseate Spoonbill. Pages 295 - 308 in James, A. Rodgers, Jr., Herbert W. Kale II, and Henry T. Smith, editors. Rare and Endangered Biota of Florida, Volume V. Birds. University Presses of Florida, Gainesville, Florida.

Florida Game and Fresh Water Fish Commission. September 1991. Florida Atlas of Breeding Sites for Herons and Their Allies, Update 1986-89. Technical Report #10. 147 pp.

Frederick, Peter C. 1996. White Ibis. Pages 466 - 474 in James, A. Rodgers, Jr., Herbert W. Kale 11, and Henry T. Smith, editors. Rare and Endangered Biota of Florida, Volume V. Birds. University Presses of Florida, Gainesville, Florida.

Ogden, John C. 1996. Snowy Egret. Pages 420 - 431 in James, A. Rodgers, Jr., Herbert W. Kale II, and Henry T. Smith, editors. Rare and Endangered Biota of Florida, Volume V. Birds. University Presses of Florida, Gainesville, Florida.

Ogden, John C. 1996. Tricolored Heron. Pages 432 - 441 in James, A. Rodgers, Jr., Herbert W. Kale II, and Henry T. Smith, editors. Rare and Endangered Biota of Florida, Volume V. Birds. University Presses of Florida, Gainesville, Florida.

Rodgers, James A., Jr. 1996. Little Blue Heron. Pages 413 - 419 in James, A. Rodgers, Jr., Herbert W. Kale II, and Henry T. Smith, editors. Rare and Endangered Biota of Florida, Volume V. Birds. University Presses of Florida, Gainesville, Florida.

Wading Bird Biology Influencing Dry Detention Area - Alico Lakeside

Biological Information

Description

The herons, egrets, ibises, spoonbills, and storks comprise the wading birds of Florida (GFC 1991). Although never accurately estimated, the total population of wading birds in Florida is believed to have fluctuated greatly over the years. Historically, many wading birds were hunted for their plumage, resulting in a drastic population decline in the early 1900s. Since that time, the populations rebounded, but a second drastic decline occurred, as estimated in 1970. The second population decline has been attributed to wetland alteration and destruction. Most recently, the population decline of wading birds in south Florida has been "attributed to degradation and loss of feeding habitat rather than loss of rookery habitat, hunting, or harassment" (GFC 1991).

Wood storks are discussed in a separate section of this report (federally listed species). The snowy egret (Egretta thula), the white ibis (Eudocimus albus), the roseate spoonbill (Ajaia ajaja), and two herons (Egretta caerulea and E. tricolor) are known to occur in the general areas that the proposed Phase IV project corridor traverses. These five species are listed as "species of special concern" by the GFC, the FWS does not list any of these birds.

Snowy egret (Egretta thula)

This bird is a medium-small, all white wading bird, often described as "dainty" in stature (Ogden in Rodgers. Kale and Smith 1996). The snowy egret is approximately 60 cm (24 inches) in length with a wingspan of 1 m (39 inches). The bill and legs are black, while the iris, lores, and feet are yellow. Skin color on the lores and feet changes to orange-red or red on adults during courtship. Breeding adults exhibit prominent white plumes on the head, neck, and scapulars, which are recurved and extend across the back to the tail. Plumes on non-breeding adults and immature birds are much less conspicuous or totally lacking.

White ibis (Eudocimus albus)

The white ibis is a medium-sized wading bird of approximately 56-cm total length with a 96-cm wingspan (Frederick in Rodgers, Kale and Smith 1996). The most distinct feature is the long down-curved bill. Plumage of adults is white except for the black extremities of the four longest primaries. (1n some lighting conditions the coloration of these extremities appears iridescent dark green.) The soft parts of adults are fleshy pink and become bright red before and during the short courtship period. White ibises are considerably sexually dimorphic with males up to 30% larger than females. The bill length is the most obvious difference in size between the two sexes. Post-fledgling birds have dark brown wings, neck, head, tail, and irides, white backs (evident when flying), and gray legs during their first year. Near the end of their first year, juveniles begin to acquire white plumage with sparse brown feathers remaining on their head and neck at the end of their second year. By the end of the third year, all brown has molted out.

Roseate spoonbill (Ajaiaaiaja)

The roseate spoonbill is a long-legged wading bird with a spatulate bill. It is the only spoonbill native to the Western Hemisphere (Bjork and Powell in Rodgers, Kale and Smith 1996). They stand about 80 cm (31 inches) high and have a wingspan of 1.3 m (51 inches) with a weight of 1,225 -1,800 grams. Adult plumage of birds greater than three years of age is quite variable: rose-pink on the back, wings, and lower breast; carminecolored lesser wing and upper and under tail coverts; a white neck and upper breast with a patch of stiff, curly carmine feathers at the base of the neck; yellowish wash on the breast adjacent to the bend-of-wing; an unfeathered head of pale green to golden-buff, with a line of black skin around the ears and back of head that sometimes extends as a "V" down the back of the neck; grayish-green to grayish-tan bill; and orange-buff tail. Birds that are one to 12 months of age are uniformly pale pink with fully feathered, white heads and necks and dark-tipped outer primaries. At one to three years of age, birds are intermediate in color, become bareheaded, and acquire the black line on the head at year two. Sexes are morphologically similar. Roseate spoonbills extend their necks straight forward with the legs trailing behind during flight. Flying patterns consist of wing flapping alternating with short glides, in contrast to the white ibis that has a more rapid wing beat.

Little Blue Heron (Egretta caerulea)

The little blue heron is a medium-sized ardeid approximately 64-74 cm (25-29 inches) in length with a wingspan of about 1 m (40 inches) (Rodgers in Rodgers, Kale and Smith 1996). Body measurements and plumage are similar for both sexes. The adult plumage consists of purplish-maroon head and neck with a small whitish region on the throat and upper neck. The remainder of the plumage is slate-blue with the distal third of the bill being black and the balance of the bill being pale yellow to grayish-green. The legs are grayish-green during the non-breeding season and black during the breeding season. During the breeding season, the plumes of the crest, lower neck, and the back become long lanceolate.

The immature little blue heron is mostly white with pale slate-gray tips on the primaries (Rodgers in Rodgers, Kale and Smith 1996). This feature is unique among the dark plumaged ardeids. The immature little blue heron has yellow-green legs and begins to acquire the dark plumage during their first spring, becoming "pied" or "calico." The areas of the crest, lower neck, and back are slowly replaced with dark plumage while the secondaries and primaries are replaced in symmetry. Breeding subadults attain the cobalt-blue soft-part colors on the bill and orbital skin, but the legs typically remain yellow-green. The full adult plumage is reached by the second year.

Tricolored heron (Egretta tricolor) The tricolored heron is a medium-sized heron at 65 cm (25 inches) in length with a long, slim neck, and two-toned color pattern (Ogden in Rodgers, Kale and Smith 1996). Adults have dark slate-colored heads, necks, and bodies except for a white rump, belly, and undertail coverts. The front of the neck has a white and rufous streak. Head plumes and elongated feathers on the lower neck and chest are purplish in color. The legs, feet, base of the bill, and bare facial skin are all yellow, with the bill darkening to dusky at the tip. During breeding, the adults have long, whitish head plumes and rufous to whitish mantle plumes. Soft parts also change color, with the bill and facial skin turning aquablue, the iris turning magenta, and the legs becoming orange-red.

Immature tricolored herons, up to about one year in age, are extensively reddish-brown on the head and neck, brownish on the mantle, and white in the same areas as adults. Typically, young birds lack plumes.

Distribution and Habitat

Snowy egret (EQretta thula)

Snowy egrets were extensively hunted for their plumes in the late 19`h and early 20`h centuries throughout North, Central, and South America (Ogden in Rodgers, Kale and Smith 1996). They became quite rare or were even locally extirpated in much of their range. Although no population data exists for snowy egrets outside the United States, they are believed to have recovered from the plume-hunting days and are considered to be fairly common to common in many regions of Central and South America.

The snowy egret was a common nesting species along the coast of the Gulf of Mexico, throughout Florida, and on the Atlantic coast as far north as New Jersey (Ogden in Rodgers, Kale and Smith 1996). Following the post-plume hunting days, the snowy egret rapidly recovered in most regions, even though they were extirpated or became rare in some locations during the plume-hunting era. Within Florida, the number of nesting snowy egrets has been declining since the 1950s.

Snowy egrets in Florida nest in both coastal and inland wetlands, commonly in mangroves or willows (Ogden in Rodgers, Kale and Smith 1996). Nesting also occurs in many woody species of shrubs and small trees, including Australian pine, cypress, pond apple, Brazilian pepper, buttonbush, and elderberry. Nearly all nesting occurs over shallow expanses of open water. Foraging takes place in a wide variety of permanently and seasonally flooded marshes, swamps, lake and stream shorelines, and water impoundments, even in temporarily flooded ditches and agricultural fields. Typically, the water is relatively shallow and calm. Snowy egrets also feed in upland grasslands and at the edges of the surf along beaches.

White ibis (Eudocimus albus)

White ibises are common breeding species in the coastal plain of the southeastern United States from North Carolina through Texas (Frederick in Rodgers, Kale and Smith 1996). Their range extends throughout wetland habitats of Central America and northern South America to the northern coast of Brazil. White ibises are common as breeding, migratory, and wintering birds throughout peninsular Florida and are probably Florida's most common wading bird. The breeding range of white ibises has extended northward since the 1960s when the birds began to decline in southern Florida. White ibises are known to migrate to Florida and Cuba during winter months, departing in March and April.

The white ibis has a broad tolerance for foraging and nesting habitats (Frederick in Rodgers, Kale and Smith 1996). Freshwater, brackish, and saline environments provide habitat for nesting and foraging. Adults appear to prefer foraging in freshwater habitats when feeding young. Young are not able to excrete salt through a nasal salt gland; therefore, this species must be provided access to fresh water in order to breed successfully. White ibises prefer relatively shallow water depths for feeding, though they have been observed feeding on lawns and pastures. Foraging habitats include bottomland hardwood and cypress swamps, river banks, salt marsh meadows, wet prairies, floating vegetated mats, mudflats, mangrove swamps, sawgrass strand edges, hydric hammocks, canal edges, beach flats, and landfills. The primary prey items include aquatic arthropods, especially crayfish and insects, with small amphibians and reptiles commonly consumed. White ibises will eat fish, but the fish must be extremely abundant or vulnerable for the ibis to catch them. This species is a tactile feeder like the wood stork. White ibises tend to nest in shrubby vegetation with moderate shade surrounded by water to prevent predation by terrestrial mammals. Their preference for nest building includes ground nests in clumps of grasses and in trees up to 15 m tall.

Roseate spoonbill (Aiaia ajaja)

Roseate spoonbills are residents along the Gulf coast of Texas and southwestern Louisiana, southern Florida, along both coasts of Central America, and through the Greater Antilles including Cuba, the Isle of Pines, Hispaniola, and Great Inagua (Bjork and Powell in Rodgers, Kale and Smith 1996).

Roseate spoonbills have not fully reclaimed their historic range in Florida (Bjork and Powell in Rodgers, Kale and Smith 1996). Prior to the mid-1800s, spoonbills nested as far north as Tampa Bay (Pinellas County) on the Gulf coast, Brevard County on the east coast and interior (17 Mile Swamp and Lake Poinsett), and south to the Marquesas and Boca Grande Keys. The nesting population was reduced in Florida to only one colony at Bottle Key in Florida Bay by 1935. Spoonbills recovered somewhat in subsequent years with a peak of 18 colonies in Florida Bay in 1978-1979. Following this peak, a second decline occurred in the mid-1980s, but rebounded to a new high of 20 colonies in 1984.

Nest placement is at about 2-5 m above the ground or on the surface of the water. Egg-laying occurs primarily between late March and June or as late as August in Florida. Clutch size is typically 2-5 eggs in Florida colonies, varying widely among colonies with a range of means of 2.47 to 4.13 eggs. The incubation period for snowy egrets is not accurately known, but is believed to be about the same time frame as the similar-sized tricolored heron (22-25 days) (Ogden in Rodgers, Kale and Smith 1996). Most young begin to leave the nests and venture onto adjacent branches when they are between two and three weeks of age. Many factors, such as predation, inadequate food resources, weather-related disturbance, and human disturbance, cause adults to abandon nesting attempts.

White ibis (Eudocintus albus)

White ibises are extremely gregarious and are seldom seen individually. Keeping with this habit, the species is a colonial nester, but is extremely nomadic in its nesting habits. Even the larger colonies are quite variable in size from one season to the next. White ibises probably breed for the first time during late spring at the end of their third year of life. The nest success rate varies from site to site and year to year, but rarely exceeds 80 percent. Clutch size ranges from one to four eggs with only one young raised to fledging age (Frederick in Rodgers, Kale and Smith 1996).

Roseate spoonbill (A'al is aiaja)

Roseate spoonbills are believed to first nest at three years of age; however, birds with subadult plumage have been observed nesting in Tampa Bay (Bjork and Powell in Rodgers, Kale and Smith 1996). The nesting season varies with the geographic region. In Florida Bay, nesting occurs from November to March while in peninsular Florida, nesting occurs from March to July. Spoonbills lay eggs at a rate of one egg every other day with incubation beginning on the day the first egg is laid. Clutch size in Florida Bay ranges from 2.8 to 3.7 eggs per nest. Productivity (juveniles 3-5 weeks old per nesting attempt) has been highly variable since the late 1930s with estimates ranging from complete nesting failure to 2.2 young per nest (Bjork and Powell in Rodgers, Kale and Smith 1996). Fledging occurs at about six weeks of age and the fledglings disperse from the nest at about eight weeks of age.

Mortality of roseate spoonbills has been attributed to predation by bald eagles and possibly turkey vultures, and to malnutrition and disease (Bjork and Powell in Rodgers, Kale and Smith 1996). Mercury concentrations in liver tissue of nestlings from Florida Bay colonies ranged from 0.16 to 5.38 ppm (wet weight). Such concentrations are similar to other wading bird species with concentrations being higher in eastern versus western Florida Bay birds.

Little Blue Heron (Egretta caerulea)

Little blue herons begin breeding during their first year of life at 11-12 months old, comprising approximately 2% of the nesting herons (Rodgers in Rodgers, Kale and Smith 1996). The eggs are pale blue and are laid over a period of several days at 1-2 day intervals. Incubation begins with the first egg laid and continues for 21-24 days. Reproduction success is affected by both inter-and intrayear variation. The modal clutch size is three eggs with a range of two to five. Hatching success is typically high (approximately 91%), but nestling survivorship beyond 10-14 days ranges from 50 to 84% (Rodgers in Rodgers, Kale and Smith 1996). Egg loss and nestling mortality is affected by starvation, collapse of nests, and predation. Typically, early nesting little blue herons exhibit larger clutch sizes and higher nestling survivorship.

Little blue heron young are semialtricial at birth (Rodgers in Rodgers, Kale and Smith 1996). The nestlings can stand and walk out onto branches at 10-12 days of age. The young are fully feathered and independent of the parents at 21-24 days of age. Fledging takes approximately six to seven weeks. Maximum life span is not known, but little blue herons probably reach at least 12 years of age.

Tricolored heron (EQretta tricolor)

Tricolored herons may nest in colonies that are small and comprised of only tricolored herons, or, more commonly, they nest in larger, multi-species colonies (Ogden in Rodgers Kale and Smith 1996). The larger colonies are usually located in coastal areas rather than in the interior, although relatively large freshwater colonies of tricolored heron occasionally form in the Everglades. Nesting tricolored herons are commonly associated with nesting snowy egrets.

Nests are simple, somewhat flimsy platforms of twigs constructed approximately two to five meters above ground (Ogden in Rodgers, Kale and Smith 1996). Egg laying begins in early February and peaks in early March within the Everglades National Park. Egg laying in other portions of Florida occurs between middle March and early June, and sometimes as late as August. Clutch size is usually three eggs with a range of two to five eggs. Incubation takes 22-25 days.

Nestling tricolored herons spend most of the first two weeks in the nests and are typically fed four to five times each day (Ogden in Rodgers, Kale and Smith 1996). At as early as 11 days, older chicks move out of the nests onto adjacent branches, but return to the nest for feeding until about the age of three to four weeks. After three to four weeks, but before seven to eight weeks of age, the chicks become independent of the adults. Young birds are still fed in the colony, but feeding occurs away from the nests. Nest success rates vary considerably among colonies and years. Primary causes of nest failures are nestling starvation, nest abandonment by adults, and predation.

Factors Affecting Decline

Snowy adret (Egretta thula)

As stated previously, in the early 1900s, plume hunting decimated the snowy egret population throughout its historic range (Ogden in Rodgers, Kale and Smith 1996). Since that time, the primary factor affecting population decline is habitat loss or alteration. It is believed feeding habitat loss within the last several decades in Florida is responsible for the population decline rather than colony destruction. The loss of wetlands continues to be the primary threat to the snowy egret. White ibis (Eudocimus albus)

Foraging habitat destruction and degradation (Frederick in Rodgers, Kale and Smith 1996) threaten the white ibis population. Human development on lakes, wetlands, and rivers is responsible for wetland eutrophication. Increased salinity in estuaries (e.g. Tampa Bay, Biscayne Bay, Florida Bay) is the result of increased human consumption of fresh water and lowering of the water table. Additionally, the disappearance of seasonally flooded wetlands can be directly attributed to human encroachment. Both processes contribute to the degradation of foraging habitat for white ibises. Large-scale degradation of foraging habitat is occurring in the Everglades through compartmentalization of the marsh, artificial manipulation of the normal hydrological cycle, and eutrophication of the marshes. Being primary and secondary consumers, the threat of bioaccumulation is not extreme; however, contamination with residues of pesticides, herbicides and heavy metals is a real danger, especially as wetlands are converted to agricultural lands (Frederick in Rodgers, Kale and Smith 1996).

White ibis colonies are quite vulnerable to human disturbance during courtship and egg laying (Frederick in Rodgers, Kale and Smith 1996). Ibis chicks will jump from the nest at an early age (10-18 days) with such behavior being contagious within the colony. Human disturbance during this stage can cause significant mortality of young due to their inability to regain the nest.

Roseate spoonbill (Ajaia ajaja)

Roseate spoonbills are particularly vulnerable during nesting season because they restrict their foraging activities to areas in close proximity to the colonies (Bjork and Powell in Rodgers, Kale and Smith 1996). Nesting distribution is influenced by loss of foraging habitat, as occurred in the Florida Keys during 1955 through 1985. Habitat loss occurred as a result of commercial and residential development. To a lesser degree, natural expansion of mangrove vegetation accounted for some habitat loss.

Nesting success is also influenced by intraseasonal changes in availability of foraging habitat (Bjork and Powell in Rodgers, Kale and Smith 1996). Typically, habitats experience a gradual dry-down with subsequent concentration of prey, facilitating feeding of young spoonbills. Flooding events, extreme temperatures, and drought conditions affect foraging habitat of spoonbills.

Human disturbance of nesting sites also greatly affects roseate spoonbills (Bjork and Powell in Rodgers, Kale and Smith 1996). Nesting numbers of roseate spoonbills declined dramatically on a Florida Bay island in direct correlation with increased boating activity. A 100-foot no-access-zone was posted around the island with patrolling by park rangers; nesting numbers more than doubled the following year.

Little Blue Heron (Egretta caerulea) Little blue herons were not affected directly by the plume trade of the early 1900s (Rodgers in Rodgers, Kale and Smith 1996). Human disturbance of breeding colonies may affect reproduction at sites used for recreational purposes. The primary sources of threat to little blue herons are alteration of hydrocyles of wetlands used for foraging and nesting and exposure to pesticides and heavy metal contamination. Additionally, little blue herons will forage at fish farms and hatcheries, which exposes them to illegal shooting.

Tricolored heron (Egretta tricolor)

The only apparent threat to tricolored herons is unstable and inadequate habitat options (Ogden in Rodgers, Kale and Smith 1996). No other threats, such as environmental contaminants, destruction of colony sites, or shooting, have been documented.

Literature Cited

Bjork, Robin and George V.N. Powell. 1996. Roseate Spoonbill. Pages 295 - 308 in James, A. Rodgers, Jr., Herbert W. Kale II, and Henry T. Smith, editors. Rare and Endangered Biota of Florida, Volume V. Birds. University Presses of Florida, Gainesville, Florida.

Florida Game and Fresh Water Fish Commission. September 1991. Florida Atlas of Breeding Sites for Herons and Their Allies, Update 1986-89. Technical Report #10. 147 pp.

Frederick, Peter C. 1996. White Ibis. Pages 466 - 474 in James, A. Rodgers, Jr., Herbert W. Kale 11, and Henry T. Smith, editors. Rare and Endangered Biota of Florida, Volume V. Birds. University Presses of Florida, Gainesville, Florida.

Ogden, John C. 1996. Snowy Egret. Pages 420 - 431 in James, A. Rodgers, Jr., Herbert W. Kale II, and Henry T. Smith, editors. Rare and Endangered Biota of Florida, Volume V. Birds. University Presses of Florida, Gainesville, Florida.

Ogden, John C. 1996. Tricolored Heron. Pages 432 - 441 in James, A. Rodgers, Jr., Herbert W. Kale II, and Henry T. Smith, editors. Rare and Endangered Biota of Florida, Volume V. Birds. University Presses of Florida, Gainesville, Florida.

Rodgers, James A., Jr. 1996. Little Blue Heron. Pages 413 - 419 in James, A. Rodgers, Jr., Herbert W. Kale II, and Henry T. Smith, editors. Rare and Endangered Biota of Florida, Volume V. Birds. University Presses of Florida, Gainesville, Florida.