We made our third and final MAPS visit on Saturday to Rock Ridge. The site is the only one of the three situated in the provincial park (the other two are on government-owned crown land), and is the only one of the three that we can’t walk in to. Well, we could, but it would take us about an hour to reach. As it is, it still takes us about half an hour, which involves a longish portage and a moderate paddle in the canoe. We’ve done this half a dozen times, but prior to Saturday all of the visits had been in the afternoon. Somehow, at 4am, it seemed like a whole lot more work than it had on previous visits, so we’re looking at ways to shorten that time and effort.
Rock Ridge gets its name from its two most obvious features. The first is a long, steep ridge that runs along the edge of one of the lakes. This is one of my favourite features of the site, as the view is amazing, one of the best that I’ve encountered around our home and the park. Our “banding station”, the spot where we leave all our tools and bring the birds back to for data collection prior to release, sits overlooking this ridge and the lake below.
And the second is the prominent rock barrens habitat that is abundant throughout the site. It is probably the site with the most Canadian Shield flavour, with rocky granite outcroppings and large stands of pine. Scattered through the area are patches of deciduous forest and successional edge habitats, which makes for an incredible diversity of birds. Scarlet Tanagers and Red-eyed Vireos sing a few dozen meters from Eastern Towhees and Field Sparrows, which in turn are singing alongside White-throated Sparrows and Pine Warblers.
The landscape owes part of its existence to fires that ripped through a number of areas of the park, long before it ever was a park. The scorching blaze seared off the vegetation, and left the soil exposed and without a strong root network to secure it. The soil is so thin in much of our region, sitting above the granite bedrock of the Frontenac Arch, that without the plants there a lot of it eroded away with wind and rain. The rock barrens are one piece of evidence of these historic fires, but another is in the form of these “driftwood” pieces. They’re scattered about the site, looking for all the world like they should have been washed up on a beach somewhere, but in actuality they’re the old, weathered remains of the trees killed some 80 years ago. Nearly all of the surviving driftwoods are the characteristic twisting shapes of cedar trunks, one of the most weather-resistant woods. If you look closely, you can see charred sections on most pieces.
Another feature of the site that I like is a second, smaller lake that borders the north edge. It’s got sheer-cliff walls that drop down to a striking blue water surface covered in lilypads. The nature of the cliff walls reminds me of quarries I’ve seen. At the turn of the century, and for the first few decades following, mining was a common occupation in this region. However, mining operations were relatively small scale back then, and it’s unlikely that any of them would have been big enough to dig a mining pit of this magnitude. The landscape is naturally quite rugged around here, so it’s not outside reason that these are natural, glacier-carved walls.
These guys, White-throated Sparrows, are among the most abundant of the species at the site. Despite this, we only caught three over the course of our morning. White-throats have tan and white morphs (the colour of the stripes on the head), previously thought to represent female and male birds, respectively, but it’s since been shown that both sexes “come in” both colours. Other studies suggest that the majority of pairings involve one member of each colour morph, which may also have led to the belief that the two colours represented different sexes. Further research has shown that white-morph birds are more vocal than tan-morph birds, and that white-morph females are even known to sing, albeit not very much. Tan-morph males sing about as much as white-morph females. Tan males are pacifists, more inclined to help with raising the nestlings, while white males are more aggressive in defending their turf and do little to help out around the nest.
A species we catch that is sexually dimorphic, albeit subtley so, is the Cedar Waxwing. For the most part females resemble males with their silky mocha bodies and black masks. However, in general females have shorter yellow bands on their tails, and fewer red waxy tips on their wing feathers. The key identifier, though, is the amount of black under the chin. In males (below) the black tends to extend right back along the throat as far as the corner of the mouth, while in females (above) the black is just a small patch by the beak, with a grayish wash on the rest of the chin. Waxwings are such sexy birds.
There are many species we get that aren’t dimorphic, however, such as this Chipping Sparrow. Fortunately, in many of the songbirds it’s possible to sex these guys based on other criteria. Female songbirds, when they’re breeding, drop the feathers from their belly and develop a vascularized, cushy surface, called a brood patch, that is used in incubating eggs. Males rarely develop brood patches, but can be told apart instead by a large swelling of their cloaca (the single orifice by which all waste is eliminated, a feature shared by reptiles), which is used in mating similar to the mammalian penis in terms of making the transfer of sperm to the female more reliable. It can be quite large, relative to the size of the bird, and maybe instead of saying “hung like a horse” we should be saying “hung like a breeding songbird”. Of course, both of these features are obscured by feathers when the bird is in the tree, so in order to determine the sex of the individual (if it’s not singing), it really is necessary to catch it.
Woodpeckers aren’t members of the songbird Order, also sometimes called passerines (Passeriformes), but are instead classified, with a few others, in their own (Piciformes), closely related on the taxonomic family tree. They, and other types of small landbirds like doves, cuckoos, hummingbirds, etc, are sometimes referred to as “near-passerines” for this close relation. Both male and female woodpeckers develop brood patches, so it’s fortunate that they’re all sexually dimorphic with the presence or absence of red patches. Check out the size of the beak on this male Hairy Woodpecker, as long from base to tip as the head is deep. Downy Woodpeckers have beaks that are only half as long as the head. Also note the fluffy tan-coloured bristles at the base of the bill. These are similar in function to the hairs in your nostrils, in that they help keep flying sawdust out of the bird’s nose as it’s hammering away on trees.
Speaking of hammering away on trees, this male Pileated Woodpecker was doing a good job of it on this tree. I encountered him a couple of times, in between two of our nets. It would be really neat if we caught him, and had a chance to see him up close, but we’d have to be very lucky not only in his trajectory but also hope that he doesn’t bounce out before we check the net. The nets are designed to optimally hold birds about the size of a warbler or sparrow. Robins and Blue Jays are bordering on too large, and anything bigger than that is hit-or-miss; they simply “fall” out of the pockets and go on their merry way. I was a bit surprised to see him there, since it didn’t seem like ideal Pileated habitat compared to the other two sites, nice mature forests with lots of snags where I hadn’t seen any.
Dan has posted a bit more about the visit at his work blog, Frontenac Birds, including more and different bird photos, and a bit more about the site itself.