By Andrew P. Weik – RGS & AWS Regional Wildlife Biologist – New York, New England
After a spring seemingly favorable to ground nesting birds such as grouse and woodcock, summer thus far, into late July, has been drier than usual in my region. In fact, the lack of rainfall across many areas of the Northeast has resulted in drought conditions (see map below). The colors on the map show yellow as “abnormally dry”, beige as “moderate drought” and orange as “severe drought”.
What effect does this have on woodcock? During normal soil moisture conditions, earthworms are more abundant in hardwood (e.g. alder) stands than under conifers (e.g. spruce and fir), and woodcock preferentially use hardwood stands presumably because of the greater prey availability in these stands; conifer stands are one of the least-preferred daytime forest covers.
Research by Greg Sepik and others, reported in the 1983 Transactions of the Northeast Section of the Wildlife Society, on woodcock at Moosehorn National Wildlife Refuge in eastern Maine in the late 1970s showed that during summer drought, woodcock shifted habitat use from predominantly hardwood cover to predominantly coniferous cover. They also greatly reduced use of night roost habitats, apparently because it was energetically unfeasible to make the dawn and dusk flights to and from the night roost areas. The authors go on to say, “By the end of August all age classes and sexes of woodcock normally have begun to increase in weight (Owen and Krohn 1973). During the last two weeks in August 1978 (the drought year) all woodcock captured were from 5-41% (mean =19%) below the average weights reported by Owen and Krohn (1973) for that period. Licinsky (1972) reported that a 40% weight loss resulted in the death of two captive woodcock, thus some woodcock in 1978 may have starved.”
Birds typically molt (drop and regrow) their wing feathers annually. This is an energetically and nutritionally demanding process. During the 1978 drought year, Sepik and colleagues found that three times as many female woodcock delayed or skipped molting some of their flight feathers compared to normal, apparently due to a shortage of food in late summer.
An important thing to remember is the 1978 drought referenced in the above study continued through August; precipitation throughout the rest of this summer could greatly alter the severity and pattern of drought.
