The histogram below shows the incomplete knowledge of the bird
as of the end of 2003, with just 30 observations.
The picture as glimpsed at first was of a short
winter season, 23 September to 20 January and subsequent
northward migration, 26 March (2003) to 11 May. The birds
are not seen at all
during the summer months, consistent with nesting in woodlands
further north from the Trent valley.
In comparison, using 439 observations
a more complete pattern emerges, at least for the past five years.
Data from 2009, 2010, 2011 and the first half of 2013 suggest that migrating birds
nowadays constitute no more than an October "shoulder" to the main
overwintering population. In spring, the last remaining birds depart for
summer breeding grounds to the north between 20-23 April. They return gradually
in the fall to overwinter. with the first arrivals around the 3-11 October.
At Presqu'ile provincial park, roughly 40 km to the south, the junco is a common spring migrant (late March to mid-May) and abundant fall migrant (mid- September to early November). There are three summer records, and the bird is also an uncommon winter resident (LaForest, 1993, pp.365-365). In Peterborough county, to the northwest, the junco is a common migrant which also overwinters, and some stay in the summer, mostly in the north of the county (Sadler, 1983, p.153; Cadman et al., 1987, pp.464-465). The presence of "visiting" birds makes it hard to determine migration times, but suggested ranges are 06 March to 16 May in spring, and 16 August to 20 October in the fall. The bird typically starts nesting in Ontario in the second half of April, and in summer is most abundant in the far north of the province, in the northern Hudson Bay Lowlands (Cadman et al., 2007, pp.572-573).
Cadman,MD, Eagles,PFJ and Helleiner,FM (1987) Atlas of the Breeding Birds of Ontario. Federation of Ontario Naturalists and Long Point Bird Observatory, published by University of Waterloo Press, 617pp.
Cadman,MD, Sutherland,DA, Beck,GG, Lepage,D and Couturier,AR (editors) (2007) Atlas of the Breeding Birds of Ontario, 2001-2005. Bird Studies Canada, Environment Canada, Ontario Field Ornithologists, Ontario Ministry of Natural Resources, and Ontario Nature, 706pp.
LaForest,SM (1993) Birds of Presqu'ile Provincial Park. Friends of Presqu'ile Park / Ontario Ministry of Natural Resources, 436pp.
Sadler,D (1983) Our Heritage of Birds: Peterborough County in the Kawarthas. Peterborough Field Naturalists / Orchid Press, Peterborough, ON, 192pp.