Nesting hawks & rare woodland butterflies


The search for new MAPS sites to join our existing Maplewood Bog and Rock Ridge stations has begun. The process is challenging, particularly here in the Frontenac Arch where ‘disturbed’ habitats with pronounced edges can be hard to find. The edges are important as this is where adults and young congregate during post-breeding dispersal, which is key to evaluating annual productivity. The heavily forested Frontenac region also tends to feature open understoreys with little shrub or sapling growth – not suitable for capturing birds using mistnets. Therefore the search feels something akin to looking for a needle in a haystack: a daunting job, to be sure, but not impossible. A needle we shall find!

Trout Lilly

Ontario Parks has been a tremendous supporter of FBS and have made a number of useful site suggestions for a second MAPS station within park boundaries. I will be checking out these various sites and will report on them as they are visited. I searched a good candidate site in a small portion of Frontenac Provincial Park today but unfortunately found nothing suitable for a MAPS site. Despite this I did have an incredible outing with some noteworthy discoveries.

Eastern White Pine

Today’s meander took me through a patch of mixed forest dominated by Eastern White Pine. Ruby-crowned Kinglets, Pine Warblers and Yellow-rumped Warblers were numerous in the canopy while newly arrived Eastern Towhees called from small rock outcrops. I came upon this excavation that was recently created by a Pileated Woodpecker, a common inhabitant of Frontenac Park. The sap was running quite thick and apparently attracted and drowned a considerable number of springtails along with a few other insects.

Woodpecker excavation

I spent an hour or two exploring the margins of many small/medium wetlands for good edge habitat but managed to find nothing of any use to a would-be bird bander. I did, however, find an impressive showing of early spring wildflowers such as Trout Lilly, trillium, hepatica, Bloodroot, Dutchman’s Breeches and Spring Beauties. After snapping a few photos, I decided to head for an area of mature forest en route back to the main road.

Red-shouldered Hawk nest

This is when things got interesting! This Red-shouldered Hawk nest was rather easily discovered in a mature Yellow Birch within a steep valley of mature hardwood forest. The adults were nearby and quite displeased with my presence! This is the first nest found by FBS in 2010, which is consistent in habitat and timing with the first nest of 2009 – a Red-shouldered Hawk nest on Canoe Lake Road. I quickly left the nest site to avoid unnecessary disturbance to the hawks, which seemed to be in the beginning stages of nest renovation.

There is a considerable amount of mature deciduous forest in Frontenac with some century old stands present. These forests are ideal for several species of conservation concern such as Cerulean Warbler and Red-shouldered Hawk. However, the ‘real’ biodiversity in these forests is exhibited by its plant and insect communities.

Woodland stream

With forthcoming Louisiana Waterthrush surveys in mind, I ambled down the bank to check on the water level and flow of this stream that courses through the forest. This past winter was the driest in decades and the lack of spring rainfall has further compounded the dry conditions. The result is very low water levels and weak flow of many streams in the park. I am hoping that we will get some decent rain in the coming weeks as the current picture for breeding Louisianas is bleak. There will be more to follow on our efforts to inventory the park’s streams for Louisiana Waterthrush.

West Virginia White at rest (finally!)

The stream valley was hopping with early spring activity and the most apparent of the beasts were these ghostly-white butterflies, which I suspected might be West Virginia Whites (Pieris virginiensis), a species of Special Concern in Canada. An impressive number of these eye catching butterflies were observed fluttering about near the forest floor. This species is known to occur in Frontenac Park where suitable habitats are found. West Virginia Whites occur in mature moist deciduous forests in isolated pockets of southern and central Ontario. They are known to occur at about 50 sites in the province and were once classified as an Endangered Species (1977). The West Virginia White is one of the earliest butterflies to emerge in spring when the adults seek out emerging toothwort, which their larvae feed on exclusively. I will be watching closely for this species during all of the work in mature forest coming up in May.

West Virginia Whites

Often one finds the most interesting things when looking for something else. The search for new MAPS sites will continue……

Red-shouldered Hawks-Canoe Lake Road

Incubating Red-shouldered Hawk

The Red-shouldered Hawk (Buteo lineatus) occurs across much of the eastern half of North America with a northern limit of central Ontario and Maine. Formerly Ontario’s most abundant hawk species, Red-shouldered Hawks declined sharply in the last century due to habitat loss and fragmentation and resulting inter-specific competition with the Red-tailed Hawk. Red-shouldered Hawks are an area-sensitive species, preferring large tracts of mature, contiguous and primarily deciduous forest cover.  This species also prefers a closed canopy of 70% or greater for successful breeding (Badzinski 2005). Territory size for the lineatus subspecies averaged 192 hectares in a Maryland study with distance between nesting pairs ranging from .37 km to 1.27 km (Steward 1949). Interestingly, this species is considered a partial migrant as it is only those individuals that breed in the northern portion of the continental range that are known to migrate south. These migrant Red-shouldered Hawks that breed in Ontario migrate relatively short distances to the United States.

The rather unimpressive photo above was taken of a incubating parent, probably a female, along Canoe Lake Road on April 27, 2009.  A pair returned to this nesting location from previous years in late March and were highly vocal during the first two weeks of courtship. The male and female were often observed together coasting on thermal updrafts around mid-day near the nest site. The pair have been nearly silent since that time and are much more inconspicuous in general since eggs were laid in the last week or so. The nest itself, compacted and disheveled by the winter, was extensively renovated by the pair in the first few weeks, and has nearly doubled in overall size since late March. It is located in a mature ash between two small ridges. The presiding male has been observed on multiple occasions bringing food (mostly small mammals) to the incubating female. The incubation period is about 33 days, which suggests that young will hatch around late May (Palmer 1988).

Cruising Red-shouldered Hawk

The Red-shouldered Hawk was listed as a Species At Risk (Special Concern) in Canada (COSEWIC) and Ontario (COSSARO) until 2007 when it was delisted largely based on results of a pioneering citizen science project. Bird Studies Canada (BSC) and Ontario Ministry of Natural Resources (OMNR) completed a thorough assessment of the population status of this uncommon raptor species by conducting annual roadside counts in southern and central Ontario from 1990-2006. The Red-shouldered Hawk and Spring Woodpecker Survey concluded that populations during that time period seemed to be stable in regions of Ontario with suitable habitat (central) and that the species was expanding northward. Of over 141 survey routes conducted during the project, there were a few that stood out in terms of the average number of hawks per route. Canoe Lake, Opinicon Lake, Otty Lake and Christie Lake, all routes located within the northern portion of the Frontenac Arch, had significantly higher counts of this species than anywhere else. This pattern of high population density in this region as well as The Land Between ecotone is also indicated by abundance and breeding evidence maps of the Ontario Breeding Bird Atlas.

Protecting the ecological integrity of the Frontenac Arch and the Southern Shield region of Ontario is important to a vast array of species, including the Red-shouldered Hawk. The contributions of the Red-shouldered Hawk and Spring Woodpecker Survey and the continued efforts of the Kingston Field Naturalists have been of considerable significance to our understanding of this species in the Frontenac Arch region. While not a focal species at this time, Frontenac Bird Studies will be conducting surveys and nest-monitoring to lend further support for this remarkable hawk in Ontario’s woodlands.