Sitewide bird observations conducted in May, June, August, and September of 1994 at BNL were used to calculate habitat-specific diversity and to compare diversity and species richness between habitats. The results of each 1000-ft and 5000-ft upland transect were pooled, the results of the six 1000-ft wetland transacts were pooled; and the results from upland transacts were discarded as no spring (May) observations were made because this habitat was added after the May survey.
The greatest number of individuals (538) and species (63) were reported from wetlands. The next richest sites, in terms of numbers of species reported, were from a transect located in the pitch pine/oak forest southeast of the sewage treatment plant (43 species) and (40 species) from a transect located in the white pine plantation/spray aeration project in the southeast portion of the site. The site with the fewest birds observed (201) and the fewest species (23) was the white pine plantation southwest of the particle accelerator ring. Factors identified as limiting the abundance/diversity of birds at this site are: lack of a water source; a plant monoculture (pines) limiting the available food supply; nearby roadways and developed areas; and human presence on the access roads and exercise paths. Wetlands provide food, water, cover, and nesting habitat for a variety of birds. In addition they are relatively isolated in comparison to the pine plantations and some pine/oak forests and thus are not exposed to human disturbance.
The results of the June 1994 breeding bird survey were compared with the 1989-1993 breeding bird data collected on the BNL site (J. Clinton unpublished data). The five dominant species observed (in descending order) in June 1994 (pine/oak, pine plantation, and wetland habitats combined) were: rufous-sided towhee, gray catbird, ovenbird, blue jay, and pine warbler. The five dominant species reported in the 1989 to 1993 breeding bird observations are (in descending order): European starling, red-winged blackbird, common grackle, mourning dove, and rock dove (pigeon). The difference in dominant species between the two sampling events is due to different portions of the site being surveyed; the 1994 data reflect species found in relatively undisturbed parts of the site, while the 1989-1993 data reflect species observed in developed portions of the BNL site. All five dominant species cited from the earlier surveys (1989-1993) were observed in 1994 among the BNL buildings and feeding along roadsides and on the recreation fields. As the European starling, red-winged blackbird, and grackle were commonly observed in large flocks, the observation of several flocks of these species could skew dominance data away from more common, widespread species that typically occur as pairs or in small flocks.
Dominant bird species observed in 1994 in each of the surveyed habitat types (pine plantation, pitch pine/oak forest, wetlands).
The dominant bird species identified in 1994 in the pitch pine/oak forest were among those that Reschke (1990) identifies as characteristic of this habitat. The dominant bird species identified in 1994 in the wetland transects were the blue jay, gray catbird, black-capped chickadee, rufous-sided towhee, and common yellowthroat.
The bird species observed on the BNL site were typical given the habitats, seasons surveyed, and degree of human abundance and diversity/disturbance. Predictably, those habitats (wetlands) with the least amount of disturbance/development contained the greatest number and diversity of species, while disturbed habitats (pine plantations) contained the fewest species and exhibited the lowest degree of diversity.
Species Accounts of Selected Birds
Common Nighthawk (Chordeiles minor)
The common nighthawk is listed as a species of special concern by the State of New York. It is an uncommon, extremely local breeder throughout the state. Its numbers have declined throughout New York, though reasons for the decline remain unknown. The nighthawk feeds on flying insects, particularly mosquitoes. It is not listed as breeding in the vicinity of BNL by the Breeding Bird Atlas, though two related species, the whippoorwill and chuck-will's-widow, are reported to breed in the area. A common nighthawk was observed on 8 June 1994 within the Gamma Forest; another was observed in September 1994 at one of the pitch pine/oak transects.
Eastern Bluebird (Sialia sialis)
The eastern bluebird is listed as a species of special concern by the State of New York. Three reasons have been cited for the decline in numbers: loss of preferred habitat (farmlands), loss of available nesting sites, and competition with the house sparrow and European starling for nesting sites. As an insect feeder (in summer), the bluebird is susceptible to pesticides sprayed on farm fields. Eastern bluebirds were listed by NYSDEC as breeding on one of four breeding blocks encompassing the BNL site.
Eastern bluebirds were most often observed within and adjacent to the particle accelerator ring in the vicinity of the ecology fields in pairs or in small flocks of four to six birds. Successful reproduction by bluebirds was not documented on the site in 1994. One nest box is located by the ecology fields and two within the particle accelerator ring. The placement (and maintenance) of additional nest boxes in likely habitats (e.g., berms around the sewage treatment plant) could increase the likelihood of eastern bluebirds successfully breeding on the BNL site. Additional nest boxes for the eastern bluebird will be installed in 2000 as part of habitat enhancement initiatives outlined in the Wildlife Management Plan.
Osprey (Pandion haliaetus)
Ospreys feed almost exclusively on live fish and typically remain near water. Reproductive failures of osprey in the 1950s and 1960s were caused by eggshell thinning and breakage linked to DDT exposure. Osprey productivity throughout the Boston-New York region and elsewhere reached very low levels. In many places, including Long Island, the population is recovering. The osprey was initially listed as a federally endangered species in 1978, but its status was changed to threatened in 1983 as the population began to recover. The osprey is no longer on the U.S. Fish and Wildlife Service’s list of threatened and endangered species, but continues to be listed as threatened by the State of New York.
One osprey was observed flying over the site at treetop level on 23 August 1994. None of the water bodies on the BNL site are large enough, or contain large enough fish, to provide habitat or food supply sufficient to support an osprey. Some of the larger ponds east of the BNL site (e.g., Grassy Pond and Horn Pond) may provide habitat for migrant or transient ospreys.
Peregrine Falcon (Falco peregrinus)
The peregrine falcon is listed as a state endangered species due to population declines from reproductive failure associated with DDT exposure (Andrle and Carroll, 1988), but was delisted by the U.S. Fish and Wildlife Service on Aug. 25, 1999. Their numbers declined greatly from the 1940s to the 1960s, to the point where they were considered extirpated from New York and the eastern of Unite State. Reintroduction began in 1974, and peregrine falcons are now nesting successfully in portions of the Adirondacks and on bridges and buildings in the vicinity of New York City. They nest on the superstructures beneath bridge roadways, either directly on the structure or in nesting boxes that have been provided for them. Populations in the Northeast are highly migratory, traveling as far as South America during winter.
Peregrine falcons feed predominantly on small birds, usually captured in flight. Birds as large as ducks may be taken, but the major food item in urban environments is pigeons (rock doves). A single adult peregrine was observed on 5 October 1994 at Zeek's Pond. The peregrine made two unsuccessful attempts to capture one of a mixed flock of wood ducks and green-winged teal. The lone peregrine was most likely a migrant, as they are expected to be infrequent seasonal visitors to the BNL site and vicinity. Since 1994 single peregrines have been seen migrating through the BNL site.
Red-tailed Hawk (Buteo jamaicensis)
The red-tailed hawk occurs in farmland and woodlands and over marshes. It is the most common and widely distributed large diurnal (daytime-flying) raptor in New York. It is quite adaptable to human changes, clearing and farming, in the environment. Some modification of habitat, including forest fragmentation and agriculture, apparently benefits the red-tailed hawk by providing additional nesting habitat and permitting access to areas formerly suited to other raptors, such as the great horned owl.
Red-tailed hawks were observed hunting over the cleared portions of the BNL sites. The Gamma Forest, gamma fields, and ecology fields were the areas where red-tailed hawks were most frequently observed. No evidence of red-tailed hawks nesting on the BNL was noted, though recently fledged nestlings were observed in August 1994. Mice, gray squirrels, and cottontails are expected to form the bulk of the redtail's diet on the BNL site. Since 1994 two pairs of red-tailed hawks have been noted along the eastern and northern fire breaks.
Virginia Rail (Rallus limicola) and Sora Rail (Porzana carolina)
The rails are secretive birds, usually residing in dense vegetation within wetlands or coastal areas, and are rarely observed. Typical food items include insects, seeds, aquatic animal life, and berries.
A virginia rail was observed near the recreation fields west of Brookhaven Avenue. As the fields and adjacent pine plantations are not typical rail habitat, it is assumed the bird was a migrant that had stopped to rest. A second Virginia rail was heard calling (30 November 1994) within the herbaceous wetland east of the east firebreak and bordering the Peconic River, and a Virginia rail was documented during the 1999 Christmas Bird Count at the same location. A single Sora rail was observed within a dense reed grass stand along the Peconic River east of the east firebreak. The bird was observed on 18 October 1994 during the wetland delineation survey. Neither species of rail is listed as breeding on the site by the New York State Breeding Bird Atlas. However, due to their secluded habitat and secretive nature, the rails are often undetected.
Reference: December 1994; Sitewide Biological Inventory, Phase II.
Note: Text citation may be found in the above reference document.
Last Modified: November 14, 2008