Photo Credit: Eric C. Soehren
SCIENTIFIC NAME: Ammodramus henslowii (Audubon)
OTHER NAMES: None.
DESCRIPTION: A small (12-13 cm [4.75-5.25 in.] long) grassland sparrow with a relatively large, flat head and a large, pale bill. Striped olive-green head and reddish-brown wings are most distinctive field marks. Tail short, and back reddish-brown with dark streaks; breast and flanks buffy, with dark streaks. Usually only observed for brief glimpses as they flush from underfoot and fly low over vegetation for short distances with a distinctive twisting motion of the tail. Rarely vocalize during winter, but breeding males sing a feeble, hiccupping, tsi-lick, that is insect-like in quality. Two subspecies described (Graber 1968): The nominate or western subspecies (A. h. henslowii), occupies the largest geographic distribution, has a thinner bill, and generally is lighter in color with heavier streaks on the back. It is the race found wintering in
DISTRIBUTION: Breeds from eastern
HABITAT: Western subspecies breeds in grasslands that contain tall, dense grasses, a high percent coverage of standing dead vegetation, and relatively few shrubs (Zimmerman 1988). Occupied both native and non-native grasslands in
LIFE HISTORY AND ECOLOGY: Although often stated to breed in “loose colonies,” males defend breeding territories and the species is not a colonial nester. Apparently monogamous; female builds nest on ground among layers of thick litter, or within large clumps of grass (Winter 1999). Both sexes brood and feed nestlings (Graber 1968). Clutch sizes range from three to five eggs, incubation lasts about 11 days, and nestlings fledge nine to 10 days post-hatching (Graber 1968). Few studies have examined breeding biology, but probably double-brooded (Winter 1999). Nesting extends from mid-May to mid-August; begin departing breeding grounds in September and most have departed by November (Graber 1968). Few data on food habitats published. During breeding season, diet apparently consists of mostly arthropods but seeds may predominate during fall and winter (Hyde 1939). Have a variety of mammalian, avian, and reptilian predators, but predation probably not a serious limiting factor. Nest predation and parasitism by brown-headed cowbirds appear relatively low. Information during winter even more limited than information during breeding season. Those wintering on pitcher plant bogs in
BASIS FOR STATUS CLASSIFICATION: Data from the North American Breeding Bird Survey indicate Henslow’s sparrows have suffered among the most drastic population declines of any bird species in
Author: James W. Tucker, Jr.