The vireo family is widespread across North America, but we have had singularly little success finding them (or certain other classes of birds, such as kinglets and wrens) across Trent Hills. Throughout Ontario, the warbling vireo breeds mainly in the south, the Philadelphia vireo largely on the southern shield and further north, and the red-eyed vireo across most of the province (Cadman et al., 1987, pp.350-355). The later edition (Cadman et al., 2007, pp.370-375) has range maps that confirm and further delineate these breeding patterns. Thus the warbling vireo is commonly found along and just south of the southern margin of the shield, through the Kawarthas and east into the St. Lawrence valley. The red-eyed vireo is a very common bird in Ontario, with a broad region of peak distribution just north from our area. The Philadelphia vireo mostly nests much further north, in the James Bay Lowlands and far northwestern Ontario.
The Philadelphia vireo is an uncommon migrant, in mid-late May and late August to late September, at Presqu'ile provincial park, roughly 40 km to the south. The warbling vireo is a common migrant and a breeding summer resident, early May to mid-September. The red-eyed vireo is also quite common in the park, from mid-May to early October (LaForest, 1993, pp.300-302).
In Peterborough county, to the north and northwest, the
Philadelphia vireo is a migrant in spring
and fall, reported 11 May to 23 June and
15 August to 27 September.
The warbling vireo and red-eyed vireo are
both common summer residents,
seen from late April to late September and even
(red-eyed vireo) as late as 09 November
(Sadler, 1983, p.130).
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.