bo37-1-web.pdf

Banding Northern Saw-whet Owls in MassachusettsEach fall, as cold weather brings snow cover to northern regions, numbers of Saw-whet owls move south in search of food and cover for the winter.These owls typically do not relocate in the same wintering and breeding areas each year as "true" migrant species do.For many purposes, however, their overall pattern of movement, southward in fall and northward in spring, is called migration.Until about twenty years ago, Northern Saw-whet Owls were thought to follow only one or two major migration routes.During the 1990s, however, the expanding network of Saw-whet banding stations across the U.S. and Canada began to document the broad seasonal movements of this species (Gentes 2002).The presence of these small, secretive raptors in Massachusetts was something of a mystery until 1994 and the start of Danielle Smith's Saw-whet banding project at Daniel Webster Wildlife Sanctuary in Marshfield (Smith 2002).In fall 2003 the owlbanding station opened at Lookout Rock in Northbridge (Clayton 2004) and joined other stations already monitoring Saw-whets in the state.Since then, in cooperation with the owl-banding network, the Lookout Rock team has learned a great deal about Saw-whets and their migration: where they come from, weather conditions that affect their flight, and some of the places they visit.Last spring, we combined the Lookout Rock data with that of other Massachusetts owl-banding stations to get a better understanding of Saw-whet migration in the state.From west to east, the six stations are Hopkins Memorial Forest (Williamstown), South Hadley, Lookout Rock (Northbridge), Drumlin Farm Wildlife Sanctuary (Lincoln), Blue Hills Reservation (Milton/Quincy), and Daniel Webster Wildlife Sanctuary (Marshfield). How Many Saw-whets Are Banded Each Year?The number of Northern Saw-whet Owls netted at banding stations varies from site to site and from year to year.Some of the fluctuation appears to be cyclical.Across eastern North America, there has been a large increase in the number banded every fourth year since 1995 (U.S. Bird Banding Laboratory).In 2006 there was a major decrease in the East -only 416 Saw-whets were netted in Massachusetts (Figure 1).In 2007, however, the six banding stations netted a combined total of over 1100 Saw-whet Owls!An interesting exception to this pattern, Hopkins Memorial Forest in the northwest corner of the state, did not experience a drop in 2006, nor did it have a Northern Saw-whet Owl.Photograph courtesy of U. S. Fish & Wildlife Service. AO = Attacks own species; AL = Attacks larger species; AS = Attacks smaller species; ABL = Attacked by larger species; ABS = Attacked by smaller speciesBirds are also in a hurry when feeding at bird feeders.The longer they are feeding on open ground or at platform or hanging feeders, the longer they are vulnerable to predation.Anyone who regularly feeds birds in winter is aware that feeders concentrate birds and attract accipiters and even shrikes.Hence, acquiring food in a hurry and thus reducing the probability of predation may make the energetic costs associated with aggression worthwhile.

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