It was a chilly start to this morning’s fieldwork but it turned into a great day on all fronts. Birds were more abundant and diverse today with many firsts of the year including Black-throated Blue Warbler, Broad-winged Hawk (two separate adults carrying food!), Solitary Sandpipers and a whopping great tally of 14 Cerulean Warblers. Yellow-throated Vireos and American Redstarts were also quite numerous.
I was thrilled to find a Northern Waterthrush in the midst of nest building along a creek near Birch Lake but the real star of the show today was the discovery of an actively nesting pair of Louisiana Waterthrushes. The pair were located in a deeply incised ravine in mature forest. I hung around for a bit to observe them and suspect that a nest containing eggs is likely to be found above the steep bank of a waterfall at the site. I didn’t have time to look for the nest but will return to the site at a later date for a checkup. To my knowledge this is a newly documented breeding location for the species.
The media file below includes pictures and a short recording of the male LOWA taken at the site this morning. Something went wonky with the image quality during conversion at Vimeo but the sound is accurate. The Louisiana Waterthrush (Seiurus motacilla) has a distinctive song, much softer, sweeter and melodic than the louder and more guttural warble of its cousin – the Northern Waterthrush (Seiurus noveboracensis).
In Canada, the Louisiana Waterthrush (Seirus motacilla) has a small range limited to southern Ontario and Quebec. The population is small, estimated at <200 pairs, and restricted to mature forested ravines with clear, gravel-bottomed streams and/or woodland swamps. Louisianas are considered “area sensitive”. According to a Maryland study (Robbins 1979) a minimum of 100 contiguous hectares of mature habitat is needed for successful breeding (McCracken 2006). In Ontario, the Louisiana Waterthrush is a rare but regular breeder in southwestern Ontario. Smaller numbers also occur in deeply incised valleys of the Frontenac Arch where mature forest is present.
The Frontenac Arch sits at the northern limit of the continental breeding range for Louisiana Waterthrush. Here, annual occupancy and productivity of breeding sites are probably influenced by weather cycles and periodic expansion/contraction of the source population further south, possibly upstate New York. It is suggested that north wandering immigrants cause a “rescue effect” for the Canadian population. There is also evidence of the species expanding its range northward, likely in response to maturing second growth forest cover. Climate change, beavers and water quality are also important influences on the status of the species in the Frontenac Arch.
We have started an inventory of Louisianas in Frontenac Provincial Park and in accessible habitats immediately surrounding the park. Louisianas will breed in woodland swamps and along clean creeks and streams, both of which occur in abundance in these areas. Potential nest sites have been identified from several sources and will be surveyed in May 2010 to determine occupancy and breeding status. This information will improve our knowledge of the local population’s size, demography and habitat preferences. The work will also enable monitoring through comparative analysis in future years.