American Woodcock Habitat Model
go to: USFWS Gulf of Maine Watershed Habitat Analysis
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Draft Date:
June 2001

Species:
American woodcock, Scolopax minor

Use of Study Area Resources:
Reproduction. The breeding range of American woodcock extends throughout the eastern half of the U.S., north of the Gulf Coast states. Their winter range includes the southern states from Louisiana east, and is limited in northern extent by snowcover and ground frost. (Keppie and Whiting 1994).

Habitat Requirements:
General: The woodcock is most closely related taxonomically to the shorebirds, but physically and behaviorally has adapted to forest and brushland habitats, possessing short, rounded wings that enable it to fly through dense cover (Owen et al. 1977). It  is common where there is an interspersion of early successional hardwood stands on poorly drained land, such as alder thickets, and which have scattered openings (Keppie and Whiting, Jr. 1994, Sepik et al. 1994, Storm et al. 1995). The openings serve both as singing grounds and as nocturnal roost sites (Johnsgard 1981, Sepik et al. 1994).

Diurnal (feeding) and nesting cover: Although insects are taken (Keppie and Whiting 1994), earthworms are the primary food resource; typically these are abundant in well drained loam soils (moisture content of 15-80%, high soil pH and/or high nitrogen; Keppie and Whiting 1994, Cade 1985). Wishart and Bider (1976) found woodcock foraged predominantly in deciduous (diurnal) habitats during the spring and summer, shifting to alder woods in the autumn. Relatively fewer woodcock use mixed hardwood-conifer, and fewest conifer (Owen and Morgan 1975, Reynolds 1977 in Cade 1985, Sepik and Derleth 1993).

Woodcock also nest and rear broods in young, open, second-growth deciduous forests with well drained soils; more commonly in open forest than in more dense deciduous sapling or conifer cover (McAuley et al. 1996). Nesting cover generally is of an upland rather than wetland character (Keppie and Whiting, Jr. 1994). Most nests consist of a shallow depression lined with a few leaves, and occasionally with twigs or stems placed around the edges. On wet ground a well formed nest cup may be evident, but nests are generally placed in drier locations, if only a hummock (Mendall and Aldous 1943).  

Display/nocturnal roost cover: In the spring, males migrate northward first, often returning while there is still snow on the ground (Owen et al. 1977). Males perform distinctive courtship flights at dawn and dusk over fields, pastures or forest/shrubland clearings.  Such openings are known as singing grounds because of the ‘peeennt’ call made by male woodcock during these flights (Owen et al. 1977). Males are polygynous (Owen et al. 1977). Dwyer et al. (1988 in Sepik et.al. 1993) suggested that females visit only males in openings near nesting areas.

Old fields, pastures, clear cuts, blueberry barrens and forest openings also are used for night roosts by post-nesting adults and juveniles as the summer progresses (Owen and Morgan 1975, Sepik et al 1994, Cade 1985). “Woodcock fly into the fields at dusk and return to daytime covers at dawn”, resting most of the time they are there (Sepik et al. 1994).

Interspersion between covers: Woodcocks benefit from interspersion of diurnal/nesting (forest, shrubland) and display/nocturnal (grassland) covers (Sepik et al. 1994). An early study by Mendall and Aldous (1943) found 24 of 29 singing grounds (display areas) were less than 100 yards from nest or diurnal cover; they regarded that distance or less as being "ideal". Average distance traveled by adults between diurnal and nocturnal covers is approximately 200 to 500 m (Dunford and Owen 1973, Sepik and Derleth 1993). Juveniles  may have a range of about 300 to 500 m (Owen and Morgan 1975, Keppie and Whiting, Jr. 1994).  However, these distances may not represent the preferred distance between shrub/regrowth and field cover types; Owen and Morgan 1975 noted that adults in nocturnal cover stayed only an average of 10 m from the edge of fields, and juveniles only 26 m.

Area: Courtship singing sites and nocturnal habitats averaged 0.4 ha in Quebec (Wishart and Bider 1976), but Keppie and Whiting, Jr. (1994) argue that summer roost fields should be over 1.2 ha. Woodcock in Maine used roost sites ranging from 0.6 to 8.2 ha (Dunford and Owen 1973), although parts of fields up to 40 ha may be used (Owen et al. 1977). Woodcock frequently are found using "portions of five or ten acre fields" (Mendall and Aldous 1943).

Limiting Factors. Nesting females are sensitive to disturbance and will readily abandon broods (Keppie and Whiting 1994). Landuses which drain or channelize wetlands reduce viable habitat, as do large scale “clean farming” practices which remove fencerows, hedgerows and grassy field margins (Owen et al. 1977). Predators include raptors, fox, raccoon, skunk, dogs, house cats, weasels and occasionally even red squirrels (Longcore et al. 1996, Longcore et al. 2000).

Model:
Sites in the Gulf of Maine watershed were scored for nesting and foraging, or for roosting and courtship, based on landcover and soil type, or landcover and area, respectively. Habitat scores then were adjusted for interspersion of these two general types.

The scores for different landcovers are given in the table, below. Because our forest landcovers did not distinguish growth stage, and the shrub class includes regenerating forest, both were regarded as potential nesting/feeding habitats, and were scored for an 'average' condition.

NWI Designations
(wetlands only)
Cover Types Cover Suitability
(0 - 1 scale)
Upland deciduous forest 0.6**
Upland coniferous forest
Upland mixed forest 0.4**
Grassland 0.8*
Upland 'shrub', (primarily regenerating forest, some blueberry fields) 1.0**,0.4*
Cultivated
Developed
Bare ground
PEM_L2EM Lake/pond, emergent vegetation
PFOcon Palustrine forest, conifer
PFOdec Palustrine forest, deciduous 0.6**
PSSdec Palustrine scrub shrub, deciduous 1.0**,0.4*
PSScon Palustrine scrub shrub, conifer
PAB_L2AB Lake/pond, aquatic vegetation
L1UB_PUB Lake/pond, unconsolidated bottom
L2US Lake, unconsolidated shore
L2RS Lake, rocky shore
R1UB Riverine subtidal unconsolidated
Rper Riverine perennial
E1AB Estuarine subtidal vegetated
E1UB Estuarine subtidal unconsolidated bottom
E2AB Estuarine intertidal algae
E2EM Estuarine intertidal emergent
E2RS_R1RS Estuarine, tidal river rocky shore
E2SS Estuarine intertidal shrub
E2US Estuarine intertidal unconsolidated shore
M1AB Marine subtidal vegetated
M1UB Marine subtidal unconsolidated bottom
M2AB Marine intertidal algae
M2RS Marine intertidal rocky shore
M2US Marine intertidal unconsolidated shore

Old fields, powerline row

1.0*

NOTES * = nocturnal/display cover
** = diurnal/nesting cover

Habitat was mapped by first selecting areas for courtship and roosting. Patches of grassland and shrub covers > 0.4 ha were regarded as suitable for those uses, and scored as indicated in the table, above; smaller patches were scored 0.

Feeding and nesting cover types within 90 m of the suitable courtship and roosting habitat then were selected.  If these sites had moist loam soils1 or if they were within 45 m of lake shores, edges of streams, or rivers, they were regarded as likely to be suitable for feeding and nesting, and scored as indicated in the table, above. If these cover types were in "dry" areas they were regarded as likely to be suitable only for nesting, and so scored at half that nominal value.

1included all loams having drainage classes = MW, W, SP, and P

Habitat Score: The overall habitat map for woodcock was based on the maximum of scores for the courtship/roosting and feeding/nesting components.

Model testing: Woodcock singing male survey data for 13 routes (some each in Maine, New Hampshire, Massachusetts) were obtained from Graham Smith (Patuxent WRC) and Robert Houston (this office) for 1996 through 2001. Additional occurrences were added from the Breeding Bird Survey and our own (Banner) observations. Twenty seven of the occurrences were used in model development.  We examined the association of courtship habitat, based on the model, with occurrences at the 38 other sites in which displaying males had actually been observed.  This was compared to the coincidence of courtship habitat with randomly distributed sites. Of the 38 sites with birds, 35 had mapped habitat, while 535 sites out of 810 randomly distributed sites had habitat. The Chi-square was highly significant, indicating that this component of the model does indicate localities useful for courtship by woodcock.

Sources:
Cade, B.S. 1985. Habitat suitability index models: American woodcock (wintering). FWS/OBS Biol. Rept. 82(10.105). USFWS.

Dunford, R.D. and R.B. Owen. 1973. Summer behavior of immature radio-equipped woodcock in central Maine. J. Wildl. Manage. 37(4):462-469.

Keppie, D.M. and R.M. Whiting, Jr. 1994. American Woodcock. The Birds of North America (100).

McAuley, D.G., J.R. Longcore, G.F. Sepik and G.W. Pendleton. 1996. Habitat characteristics of American woodcock nest sites on a managed area in Maine. J. Wildl. Manage. 60(1): 138-148.

Longcore, J.R., D.G. McAuley, G.F. Sepik and G.W. Pendleton. 1996. Survival of breeding male American woodcock in Maine. Canadian Journal of Zoology 74: 2046-2054.

Longcore, J.R., D.G. McAuley and G.F. Sepik. 2000. Survival of female American woodcock breeding in Maine. In: D.G. McAuley, J.G. Burggink and G. F. Sepik, Proceedings of the Ninth American Woodcock Symposium. USGS, Biological Resources Division Information and Technology Report USGS/BRD/ITR-2000-0009, Patuxent Wildlife Research Center, Laurel, MD. pp.65-76.

Mendall, H.L. and C.M. Aldous. 1943. Ecology and Management of the American Woodcock. Maine Cooperative Wildlife Research Unit, Orono, ME.

Owen, R.B. and J.W. Morgan. 1975. Summer behavior of radio-equipped woodcock in central Maine. J. Wildl. Manage. 39(1):179-182.

Owen, R.B, J.M. Anderson, J.W. Artmann, E.R. Clark, T.G. Dilworth, L.E. Gregg, F.W. Martin, J.D. Newsom and S.R. Pursglove. 1977. American woodcock (Philohela minor= Scolopax minor of Edwards 1974). Pp. 149-186 in G.C. Sanderson (ed.) Management of Migratory Shore and Upland Game Birds in North America. International Association of Fish and Wildlife Agencies, Washington, D.C. 358 pp.

Sepik, G.F. and E.L. Derleth. 1993. Habitat use, home range size, and patterns of moves of the American woodcock in Maine. Pp. 41-49 in Longcore and Sepik (eds.) Proceedings of the Eighth American Woodcock Symposium. Biol. Rept 16, USFWS, Washington, D.C.

Sepik, G.F., R.B. Owen and M.W. Coulter. 1994. A landowner's guide to woodcock management in the Northeast. Maine Agric. Exp. Sta. Misc. Rept. 253.

Sepik, G.F., D.G. McAuley and J.R. Longcore. 1993. Critical review of the current knowledge of the biology of the American woodcock and its management on the breeding ground. Pp. 98-104 in Longcore and Sepik (eds.) Proceedings of the Eighth American Woodcock Symposium. Biol. Rept 16, USFWS, Washington, D.C.

Storm, G.L., M.J. Lovallo, D.S. Klute, W.M. Tzilkowski and T. Delong. 1995. Predicting American woodcock presence in Pennsylvania from local and landscape-scale habitat variables. Northeast Wildlife 52:39-48.

Wishart, R.A. and R. Bider. 1976. Habitat preferences of woodcock in southwestern Quebec. J. Wildl. Manage. 40(3):523-531.