Some Blue Jays are year round residents in all parts of their range, many migrate generally south from the breeding range, while others may arrive from further north to augment the winter population [Tarvin and Woolfenden 1999 (BNA)]. They breed from eastern British Columbia east to Newfoundland; south throughout the US from western Texas east to Florida, but not south of the US [AOU 1998]. This range has expanded westwards, beginning in the late 1940’s, increasing dramatically in the 1970’s [Campbell et al. 1997]. Blue Jays breed in all forests, woodlands, towns and suburban areas, particularly when there are oak trees present [Tarvin and Woolfenden 1999 (BNA)]. The winter range is similar; some birds remain in the breeding areas all winter, while a variable number move generally south, though not perhaps into the peninsula of Florida [Stevenson and Anderson 1994]. Winter habitat is similar to breeding habitat, although human-supplied food in bird feeders often becomes a staple food source [Graber et al. 1987].
This species is the only New World jay showing substantial migration [Tarvin and Woolfenden 1999 (BNA)]. Spring migrants move over the whole range from late April-late May, even well into June in Vermont [Laughlin and Kibbe 1985]. Flocks can often be seen migrating south diurnally (during daylight) in fall in September and October. Over 1,000 have been recorded at Mt. Tom, MA and Lighthouse Point, New Haven, CT [Veit and Petersen 1993]. Individual migrants banded at Manomet in eastern Massachusetts over the last 40 years have been recovered as far north as Gaspe, Quebec, and as far south as South Carolina [T. Lloyd-Evans, pers. com.]. Because Blue Jays are so dependant on acorns for winter food, the numerically greatest fall migrations are usually correlated with a regional failure in fall acorn crops, and vice versa, e.g. Veit and Petersen [1993].
Breeding Bird Survey [BBS] data showed a population decline of 1.7% per year in eastern North America from 1966-1996 [Sauer et al. 1997], with more recent data through 2003 indicating stable populations in VT, but significant declines in NH, MA and CT [BBS]. Manomet migration banding data from eastern Massachusetts from 1970-2001 indicated an approximately 2% decline per year, spring and fall [Lloyd-Evans and Atwood 2004]. The reasons for these population declines, and their effect on Blue Jays as predators of other birds’ nests are not clear [Tarvin and Woolfenden 1999 (BNA)].
|
|
 |
Observations
While some Blue Jays are year round residents throughout the entire range, more migrate during spring and fall. They breed in a wide variety of forest, agricultural and suburban habitats. A sites showed the overall highest density in all states and periods, with a drop off in B and C sites in all states. CT showed the highest densities, followed by NH.
Blue Jays were present throughout the spring with presumed migrants peaking in period 3 in MA and NH; period 4 in CT and VT. Although we cannot easily separate our resident birds from migrants, small flocks of diurnal (daytime) migrants were observed at A sites, moving north up the river. On 16th May, flocks of 24, 11 and 6 birds were noted at CT A sites. |
|
|
|
|
