Rock Barrens – Geomorphology, Fire, & Prairie Warblers

Frontenac Provincial Park lies within the Grenville Province of the Canadian Shield. About 800 million years ago, the Grenville Province was a towering mountain range with peaks as high as the modern day Himalayas. Subsequent periods of erosion, sedimentation, glaciation and more erosion has created the current landscape as we see it today. The rock barrens, in their present myriad of forms and age, cover a significant portion of Frontenac Provincial Park. Geologically, the barrens are described by Christian Barber as a:

“football-shaped body of Diorite that rose up from great depths as a very hot, semifluid pluton.” (Barber 2005)

Three significant forest fires have occurred in the barrens since the mid-19th century. These fires and also the hard bedrock has limited soil generation and plant growth. Both geological and cultural histories have played a role in the creation and maintenance of these open rock barren habitats. The above picture is from the top of a ridge overlooking Slide and Buck Lakes, the most rugged area of the park that stretches from here in the south to our Rock Ridge MAPS site about 6km to the north.

This excursion involved a lot of exercise – over 10km of paddling and about 6km walking. Several pairs of loons would come over quite close to the boat and check me out. Not sure why they do this, maybe the paddling and noise stirs up prey under the surface? I’ll never get tired of seeing Loons.

These are the aforementioned rock barrens. The last fire burned this area over around 1930, which demonstrates the remarkably slow rate of succession in the barrens. The few scattered trees are no more than 5 or 6 metres tall. Eastern Towhee, Field Sparrow, Common Nighthawk and Prairie Warbler are attracted to these habitats for its absence of tree/canopy cover, presence of low shrubby growth and/or sparse ground cover.

During the morning I completed a brand new point count route through this area to boost our monitoring coverage of this unique habitat. I was also hoping to find and georeference Prairie Warblers, a recently de-listed Species at Risk that is still quite rare and isolated in Ontario. They occur along a narrow band at the southern edge of the shield – from the Frontenac Arch Biosphere Reserve in the east to the Georgian Bay Biosphere Reserve in the west. Rock barrens can be found throughout the shield but they are most widely distributed and heavily concentrated along this ecotone in central Ontario. This photo shows a small stretch of habitat incised by a wetland that held five Prairie Warblers. The deciduous tree on the right seemed to be a prominent song perch, which three gorgeous males aggressively fought over.

By the end of the day, over a dozen Prairies were located and mapped, which was a terrific reward for such a long day. I have two more “inventory” sessions for Prairies in the area still to come so there should be more of these bright yellow “buzzers” out there. This inventory will set the basic population parameters for potential future research, which would involve a more in-depth look at demographics and habitat preferences. The Prairie is one of a host of species that depends on cyclic disturbance, natural or anthropogenic, to maintain stable and viable populations. It is likely that, without another significant fire, the Prairie Warblers in Frontenac Park will be extirpated as these rock barrens mature. This is definitely a fascinating context for a detailed study…

Surveying the Mixed Forests

Eastern White Pines

This past week I finished up the remaining point count routes, which included a route through coastal mixed forests along the extreme eastern edge of Frontenac Provincial Park. I accessed the habitat via a lengthy stretch of the Cataraqui Trail. Weather was perfect for surveying and it was fabulous to get and see this area of the park. Dominant species encountered during the morning were Yellow-rumped Warbler, Pine Warbler, Chipping Sparrow, Black-and-white Warbler and Red-eyed Vireo with a few “goodies” mixed in here and there.

Atop a ridge looking to Buck Lake

The survey route passed through a wide variety of habitats but the main target was mature mixed forest occurring along shorelines of large lakes in the area. Most lakes around here are steep in slope along the perimeter and lined with a high percentage of Eastern White Pine and Eastern White Cedar but I wanted a route that could be accessed relatively easily on foot.

Waterfall near Slide Lake

I was impressed with the high number of clear, gravel bottomed, moving streams in this area of the park. Since early June I’ve been logging locations of suitable stream habitat for breeding Louisiana Waterthrushes with the intention of returning in May, 2009 to inventory populations of this species in Frontenac Park. This particular stream was quite a torrent along its length, ending with a flourishing waterfall as it emptied into South Bay of Buck Lake.

Prairie Warbler habitat

The most significant finding of the morning was of a small colony of Prairie Warblers along the sloped and scrub-bearing banks of Slide Lake!

Prairie Warbler habitat

This is fairly typical habitat for this rare warbler in Ontario-rocky shorelines of lakes with a large component of successional scrub habitat.

I recorded this video with my ancient Canon A70 point and shoot camera to try and capture some audio of the singing males. A male flew into the small tree directly behind where I sat for a break at the end of the day and sang repeatedly at close range. I wish I’d had my HD camera as this particular male remained very close for about 10-20 minutes.

Surveying the pine barrens

1st panamoric shot of wetland/pine barren habitat

The first of two point count survey routes through rock barren environs in Frontenac Park was completed this past week. It has been tough going for scheduling and conducting surveys this season as the weather has been largely uncooperative for both roadside and off-road surveys of breeding birds. Cool temperatures, high winds and precipitation limit bird activity, which greatly reduces the validity of the data being gathered. This is the main reason why these surveys have yet to finish, however they should be wrapped up by the weekend (fingers crossed).

106 point count stations are now “in the books”, the last batch of which were drawn from rock barren habitat in Frontenac Provincial Park on June 20th, 2009. It was a long day of hiking, spanning over 12 kilometers through the deep interior of the park’s southeastern portion. The habitat was stunning and full of birds and other wildlife, which made for yet another exhilarating day of field studies on the Frontenac Arch. This particular section of the park is HEAVILY laden with irregularly sized and shaped wetlands ranging from beaver ponds, lakes, swamps and sloughs. More than once I was forced to wade through the water waist high in order to stay on course-there was simply no way of getting through it without a long and wasteful detour. I don’t normally object to getting a bit wet as needed but these wetlands are very soft-mud bottomed types with imperceptible footing and a great deal of mushy unpleasantness-not to mention saturated with unseen snapping turtles! In the end though, my way was found and I took in the ordeal with a balanced sense of bemusement and humour.

blueberry season arriving

Blueberry, probably Vaccinium corymbosum or High-bush Blueberry, was a dominant ground cover species in areas with enough moisure (i.e. everywhere). The fruit is just starting to mature and should be edible soon. I have yet to associate any particular bird species with this plant but I can imagine that Nashville Warblers would find it an appropriately dense-low growing cover for their shallow cup nests. Blueberry is common throughout the park but is particularly abundant in rock barren areas running in a gradually narrowing band from the park’s south end through to Big Clear Lake in the northeast.

Prairie Warbler turf

The very first survey of the day yielded Virginia Rail, multiple pairs of Wilson’s Snipe and a distant Prairie Warbler-not a bad start! The next station, some 330m away, got me closer to the Prairie Warbler territory, which is pictured above. The male was constantly singing from the the dense shrubs lining a wet draw astride a rock wall. I had no time to investigate this particular territory any further but I’ve been pleased enough overall with having mapped several territories of this species in interior and atypical habitat associations. Prairie Warbler is a rare breeder in Canada with a very patchy and sparse distribution along the southern shield ecotone in Ontario.

Mixed-forest habitat near Slide Lake (FPP)

The route carried through a habitat I hadn’t yet sampled this season, mixed-forest dominated by Eastern White Pine and Red Pine. This area was “loaded” with Yellow-rumped and Pine Warblers, Chipping and White-throated Sparrows and lesser numbers of Blue-headed Vireo. The highlight of the birding was an adult Great Horned Owl with a fluffy youngster within 75m during a survey. Great Horned Owl is considerably less common than Barred Owl in this region.

panoramic shot of pine barren habitat

This is the last of the panoramic shots I took of the area during the day. I was hoping that the widescreen view might help in providing a sense of scale and depth of the habitat. Vegetation in the area is quite stunted, reflective of shallow till and extensive rock outcrops. This park “ecozone” is a stark contrast to the mature woodland featured earlier, with its abundant Cerulean Warblers and towering century old ash, maple and oaks. Just a few kilometres away, Wilson’s Snipe, Eastern Towhee, Field Sparrows and Common Nighthawks, among others, inhabit vast expanses of moss and lichen covered rock with ripening blueberry shrub and stunted pines. These contrasts are a defining feature of the Frontenac Arch, an undulated, ever-changing landscape of immense diversity.