Habitat Fragmentation and Breeding Birds at NASA Goddard Space Flight Center, Greenbelt, Maryland Dr. Lowell Adams Natural Resources Management Program University of Maryland College Park, MD 20742
Urban development fragments wildlife habitat into smaller, more isolated units. So what? Habitat fragmentation results in fewer numbers of species. (Loss of biodiversity) Why?
Island Biogeography Theory
A local example NASA Goddard Space Flight Center Greenbelt, Maryland
Procedures Birds n Point counts and transect counts for breeding birds (Ralph et al. 1995, Bibby et al. 2000)
Procedures Birds n 5 -min point counts conducted in large woodlots within a 50 -m radius of each point n Transect counts conducted through center of small woodlots (5 min/100 -m transect) n 7 -10 surveys conducted at each site during June 2002 n Counts conducted from sunrise to 9 am during fair weather conditions n All species seen or heard and number of individuals/species recorded n Individual birds recorded only once/survey
Number of species of breeding birds in forest fragments _________________________ Forest fragment size ___________________ Large Medium Small (x = 15. 82 ha) (x = 2. 83 ha) (x = 0. 36 ha) __________________________________ Median number of species 19 20. 5 11 Range 14 -25 14 -24 7 -14 n 19 10 11 H’ = 23. 04, df = 2, P < 0. 001 ___________________________________
Area-sensitive Forest Birds (Darr et al. 1998) Forest fragment size Large Medium Small Red-shouldered hawk x Yellow-billed cuckoo x x Red-bellied woodpecker x x x Hairy woodpecker x x x Pileated woodpecker x Eastern wood-pewee x x x Acadian flycatcher x x White-breasted nuthatch x x x Blue-gray gnatcatcher x x x Wood thrush x x Yellow-throated vireo x x Red-eyed vireo x x Northern parula x x Black-and-white warbler x Worm-eating warbler x Ovenbird x x Louisiana waterthrush Not recorded Kentucky warbler Not recorded Hooded warbler Not recorded Summer tanager x Scarlet tanager x x
Area-sensitive Forest Birds (Species recorded only in large fragments) Red-shouldered hawk (5 recorded) Pileated woodpecker (2 recorded) Black-and-white warbler (1 recorded) Worm-eating warbler (5 recorded) Summer tanager (1 recorded)
Area-sensitive Forest Birds 29 wood thrushes recorded in large fragments (1 in medium fragments) 55 ovenbirds recorded in large fragments (3 in medium fragments) 31 scarlet tanagers recorded in large fragments (3 in medium fragments)
Distribution of “suburban residential” birds at NASA Goddard Space Flight Center, Greenbelt, Maryland, summer 2002. ________________________ Forest fragment size Suburban residential birds __________ (Aldrich and Coffin 1980) Large Medium Small ________________________ Blue jay x x x American robin x x x Gray catbird x x x Northern mockingbird xx x European starling x x Northern cardinal x x x Song sparrow x x House sparrow x x x ________________________
Suburban Residential Birds Most Abundant in Small Fragments Gray catbird (6 of 36 in large fragments) House sparrow (1 of 23 in large fragments)
Suburban Residential Birds Most Abundant in Medium Fragments Northern mockingbird (4 of 39 in large fragments) All European starlings (40) in medium and small fragments on more developed west campus.
Most Abundant and Widespread Species Tufted titmouse Carolina Chickadee Carolina wren Combined, made up 28. 5%, 37. 0%, and 33. 7% of the bird community in large, medium, and small fragments.
Procedures Owls n Tape playback recordings for screech, barred, and great-horned owls
Great horned owl (0. 14) Barred owl (0. 29)
Eastern screech-owl (0. 14) Barred owl (0. 71)
Summary 1. Seventy species recorded in breeding bird survey. 2. Small forest fragments contained about half the number of species in large and mediumsized fragments. 3. Small fragments do not provide habitat for “area sensitive” species in need of conservation.
Summary 4. Any additional fragmentation of forests at Goddard will further impact forest bird species most in need of conservation. 5. Species most likely to be lost with further fragmentation are summer tanager, blackand-white warbler, and worm-eating warbler.
Summary 6. Three owl species were recorded (eastern screech-owl, barred owl, and great horned owl). All were located in large forest tracts. Loss or modification of the large forested fragments would be detrimental to these species.
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