W Week – Warblers

Black-and-white Warbler

I thought this week I would do a W theme. I have several items I want to post about that are all W’s; this first one is Warblers. In the last couple of weeks we’ve had lots of warblers returning and settling in. One of the species that seems to be singing somewhere every time I go out on a walk is this one, the Black-and-white Warbler. They are an abundant species on the rough Canadian Shield, but also found more sparsely throughout much of the rest of Ontario. They nest in deciduous and mixed woodlands, which are extensive in this region. The habitat type is also increasing in Ontario, as abandoned fields slowly return to forest, and they’re one of a number of warblers dependent on such habitat to show a statistically significant increase in the most recent Breeding Bird Atlas. Black-and-white Warblers have a distinctive foraging style, climbing up tree trunks and along branches a bit like a nuthatch; indeed, some earlier names for the species included Creeping Warbler, Pied Creeper, and Black-and-white Creeper. This one’s a male because it is crisp black and white, with a black throat; females lack the dark throat and are more grayish than black.

Nashville Warbler

Here’s another species we’ve seen a fair bit of: Nashville Warbler. Like the Black-and-white, they’re found through much of Ontario. They have a preference for mixed or coniferous forests, and all of the encounters we’ve had with individuals on apparent breeding territory have been in patches of evergreens. They’re flashy little birds, with a gray hood and bright yellow belly. In our region of the province their population seems to be stable, probably because regenerating forest here is mostly deciduous, which doesn’t affect them too much given their habitat preferences.

Yellow-rumped Warbler

Yellow-rumped Warblers should be breeding in our forests as well this summer. They’re one of the most abundant migrants in the spring, but most of them carry on past us and head for northern Ontario, and especially northwestern Ontario where they have the highest densities. Like the Nashville, they prefer coniferous and mixed forests, but are less picky than Nashvilles, making do even with small patches. Their population, interestingly, has been on the rise in our region; presumably it’s this generalist nature that allows them to take better advantage of small opportunities. There are two subspecies of Yellow-rumps, one with a yellow throat, and the other with a white throat. Ours has the white throat, and was known as a Myrtle Warbler before the two species got lumped into one. Many birders affectionally refer to them as “Butterbutts” for their namesake plumage feature.

American Redstart

American Redstarts such as this handsome male are fairly common in much of Ontario. They are very much the generalist, nesting in open and semi-open treed habitats, usually successional forests but occasionally more mature forests if they are very open or have large clearings (like along roadsides). Another species that’s on the rise, the mature males are unmistakable in their smart black-and-orange plumage. However, they don’t actually attain these colours until their second summer; their first summer is spend as a drab brownish-gray like the female. Though these young males will occasionally still try to sing and defend a territory where they’re able, not all will attract a female and mate.

There is some debate as to why some species do this, but often it’s associated with maximizing breeding success. In such species, often first-summer males who are inexperienced in holding and defending territories will have very low success compared to more experienced males. Most, if they mate at all, do so through surreptitious forays into the competitor’s territory while he is away for adulterous liaisons with the competitor’s wife. Their dull plumage helps them to fly under the radar, since from a distance they just look like a female, who doesn’t attract the attention that black-and-orange plumage would. The female, for her part, is interested in these sneaky encounters because sperm from many males helps maximize the overall fitness of her clutch; it’s more likely that some of her offspring will succeed through survival of the fittest than if they come from a single parent. She hedges her bets – rather than all or none, she goes with the less risky all or some.

Golden-winged Warbler
Photo by Dan

And finally, a species that is much less common in the region, but which has a stronghold in the Frontenac Axis, one of just a handful such areas in the province, the Golden-winged Warbler. It is a species in decline, one of the most rapidly disappearing in North America, and listed as Threatened in the province. It is being outcompeted by the closely related Blue-winged Warbler, with which it hybridizes in zones of overlap between the two species. Historically in the province, Golden-wings were more northern in range, and Blue-wings more southern; the first Blue-wing wasn’t recorded in the province until the early 1900s, but have continued to expand northward since, pushing the Golden-wing out of the southwestern regions where it was once more plentiful. Hybrids are fertile and usually backcross with one parent species or the other, further diluting the species pools (this does lead to the question of whether they are even separate species at all if their offspring are fertile, or if they’re simply two subspecies with very different plumages). Compounding the problem is loss of habitat on both summer and winter grounds, and nest parasitism by the Brown-headed Cowbird, which favours the same open, scrubby habitat the Golden-winged Warbler likes.

Beyond just these five, we also have Cerulean, Pine, Black-throated Green and Yellow Warblers, as well as Ovenbird and Northern Waterthrush, back on territory around our house. We can probably expect them to be joined by Chestnut-sided, Magnolia, Black-throated Blue, Blackburnian, Prairie, Mourning, and Canada Warblers, Common Yellowthroat and Louisiana Waterthrush, all of which are also found in the habitats of Frontenac Provincial Park and surrounding area. Twenty breeding species, what a smorgasbord. Although we won’t encounter all of those during our MAPS surveys, we will probably see most, and I’m really looking forward to those field days.

Birds on the rail line

Rails

A couple years ago (has it been that long already?) I did some bird surveys for the City of Toronto as part of an assessment and preliminary monitoring scheme for a park in the Don Valley. They’ve recently contacted me again, looking to see whether I would be available to do another set for a different site. They’re just looking for an inventory of the bird species found using the site, which doesn’t require lengthy or involved surveys, so I said I’d take them on. I’m just going to be doing area searches, once a week, from now through June, to get a basic idea of what can be found there.

Today I met the woman from the City who I’ve been corresponding about it with, at the actual site. The site is located in the southern Don Valley, only about a five minute drive from my home. I’m surprised not to have known about it, but I don’t drive that way ever. It’s actually a capped and regenerating landfill, a couple decades old, now used as a natural area for outdoor recreation. We walked into it briefly and scoped it out. She answered a few of my questions, I answered a few of hers. We didn’t spend too long there; since it’s not a very complicated project, there wasn’t a lot to be worked out. Once we wrapped up there, I grabbed my camera gear and walked back in, along a different trail, to see what I could see.

I happened across these train tracks. They obviously hadn’t been used in some time; the rails were all rusty, and there were plants growing up between the ties, right next to the steel. I decided to wander along their length a short ways; it had the advantage of not being used by the many other park users, and I had no worry about a train coming along to flatten me.

American Redstart and Yellow Warbler

Especially in the city, rail lines make really great green corridors by which wildlife can move from one area to another. Very rarely does the city come right up to their edge, usually there’s a green buffer of trees and other vegetation that borders each side of the tracks. Although it wasn’t the case here, oftentimes that’s the largest contiguous stretch of habitat within a neighbourhood. As a result, it usually has lots of creatures living in it.

One of the first birds I noticed upon stepping out on the tracks was a male American Redstart. He was singing his heart out from a Manitoba Maple that overhung the ditch on the other side of the rails. Although redstarts can have somewhat variable songs, their most characteristic and distinctive songs is a slightly rising warble ended with a downward buzzy-ish note sounding something like a sneeze.

American Redstart

I started pishing to try to call them forward to the front of the tree. Pishing is a birder’s term used in reference to a sound rather like “pishpishpishpishpish”, said very rapidly. Many birds will become curious or agitated by the sound and come in to check it out. The theory is that it resembles the distress call of another species, in particular the Tufted Titmouse. When members of the tit family start giving their alarm calls like this, it’s usually a call to other species to come help – “Danger! Here! Mob it, mob it!” If you can sound sufficiently like an alarmed titmouse, you should be able to create the same reaction. Sometimes the birds ignore you entirely, but in this case it was quite effective. At one point (captured here), the redstart actually swooped down low over my head, either searching for, or mobbing, the source of the sound.

Male redstarts take a couple years to get this nice crisp black-and-orange plumage. In their first summer as an adult they still sport the brown-and-peach colouration of the females, although it’s often mottled black, especially around the face. That fall, when they go through their complete moult, they’ll replace all their drab feathers with striking black ones. This delayed mature plumage fits into the dominence hierarchy; black males almost always get to mate, brown males only if there aren’t enough black males to go around. Not that that stops them. Brown males will float between the territories of black males, and when the older one’s got his back turned, the younger one will usually slip in for a quick fling with the missus. The females have no problem with this; the more males she mates with, the better her chances of having mated with a genetically superior male. This guy probably wasn’t going to stick around to breed, though – although they do nest in the Greater Toronto Area, he was probably heading further north to better habitat.

Yellow Warblers

There were a couple of Yellow Warblers hanging out in the same tree as the redstart, checking me out as I pished at them (you can see one with the redstart in the earlier photo). It appeared to be a male and an older female (differentiated from younger females by the brightness of her yellow plumage), but could have been two males. Yellow Warblers might be the most common warbler in the Don Valley, and probably much of southern Ontario. They’re usually found in riparian areas, in the scrubby vegetation that lines stream and wetland edges, but can occasionally be found in other habitats, as long as they’re similarly shrubby. It was a bit odd to see the pair at the rail tracks, since there didn’t appear to be water immediately nearby, but I will admit I didn’t know what was on the other side of the berm bordering the north side of the tracks.

Northern Cardinal

Mrs. Cardinal came out and gave me a good look just to make sure the fuss wasn’t anything worth getting too upset about.

Northern Cardinal

Mr. Cardinal did the same, but hung back in the vine tangles. Neither of them stuck around long once they determined that it wasn’t actually a titmouse getting worked up over an owl or something. The tangled thicket they were hanging out in was a good place for a cardinal nest, but I didn’t actually climb up to check the area out. Cardinals actually used to be fairly scarce through this area, some decades ago, but are now a dime a dozen. The reason for their expansion is usually credited jointly to the increasing popularity of bird feeders along with gradually warming average temperatures. It’s been observed that as the temperature isotherm for the January mean minimum temperature of minus 16 C moves north, so does their range. Their northern range limit is now more restricted by availability of their preferred habitat than by temperature.

Gray Catbird

A catbird was singing from a patch of sumac along the edge of the tracks, and stopped to come check me out as I pished. Catbirds take their name from the sound they make when alarmed – which sounds rather like the nasal mew of a cat. They’re a member of the family Mimidae, the mimics. Along with the Northern Mockingbird and Brown Thrasher, the Gray Catbird will pick up sounds from its environment and work them into its song repertoire. A single catbird may have dozens of different phrases. Male and female catbirds look the same; rather than looking at flashy plumage to choose a mate, female catbirds prefer males with larger, more complex repertoires, which presumably indicates greater intelligence and stronger genes.

There were also other birds along the corridor: a few American Goldfinches, an American Robin, a Baltimore Oriole, a Warbling Vireo… These guys weren’t as obliging for a photo, tending to remain higher up in the treetops, hidden behind leaves and out of the reach of my camera. There were many other bird species in the rest of the park, as well, but even just in this small stretch of train tracks I was pleased with the diversity I found.