Friday, March 9, 2012

A Quest for the Golden Swamp Warbler

Ever since I really got into birding (almost four years ago now) and started exploring the woods around my house through the eyes of a birder, one question has been burning in my mind that remains unresolved to this day: where are the prothonotaries?

Unlike many similar questions I've had concerning the absence of species despite apparently suitable habitat, which are often settled after either finding the species or discovering some critical piece of missing microhabitat, the more I learn about Prothonotary Warbler habitat, the more perplexed I am at their truancy from this area.

This is a map of the area in question, with apparently suitable habitat for prothonotaries highlighted in yellow, both bordered by bodies of water (Grand River to the north and Williams and Browns Lake to the south).  Specifically, these areas are what I would generally call flooded hardwoods, dominated by Red Maples, oak spp., elm spp., and birch spp. (my guess is River Birch, but I have little experience in tree identification).  As you might guess from the nature of this post, this is exactly what prothonotaries prefer to nest in (at least when they're this far north).  Here a a few shots of the habitat from yesterday:

...including a couple close-ups of key trees...

Birch spp.

I think this is a Red Maple...

A bit of searching around on the web has revealed that the following habitat features are important in habitat selection for Prothonotaries:

1) Prefer to nest over large bodies of standing/slow-moving water -- this area borders a slow-moving portion of the Grand River, two lakes, and usually remains flooded well into June/early July.

2) Low elevation and flat terrain are preferred -- low elevation is definitely 'achieved' here and the flooded woods themselves are flat, though the deciduous forest between them is fairly hilly.

3) Canopy height of 12-40 m with 50-75% cover -- yes on both accounts.  There's also a fair bit of diversity in both tree age and canopy cover, both apparently due to fallen trees, which is an indicator of a healthy, mature forest.

4) Forest ≥100 ha -- a quick and dirty estimate using Google Earth puts the northern portion at 13 ha and the southern portion at about 17 ha.  This might be the most obvious factor preventing prothonotary presence, though I'm not sure if this is limited to flooded areas where the birds would directly nest or the forest as a whole.  At any rate, the entire area only comes to about 33 ha.  This does not include adjacent areas that are, for the most part, fragmented only minimally by a few roads and houses.

5) Low exposure to sun -- plenty of this.

Despite the potentially limiting factor of acreage, I plan on installing a few nest boxes in the weeks to come in hopes of luring some warblers into the area this spring.  As many as eight warblers have been reported singing from the Grand River just north of town (in the Berry Rd. area), so I'm somewhat confident that prothonotaries might at least travel through this area (indeed, I got my life Prothonotary during fall migration of 2008 at Dahlem).

A few additional shots from yesterday's trek:

Filamentous green algae(?)

Bark beetle work...

...and a close-up

I'm not sure what's going on in this last photo, but this really stood out against the rest of the dark leaf litter below the water.  Whatever this is, it appeared to be pretty superficial, being restricted to a small layer on top of the leaves.

This is an attempt at cellestial photography that I made at something like 1:00 am yesterday while waiting in vain on the aurora borealis.  I think my telephoto lens has interesting potential for this type of stuff, but I'll definitely need to get my hands on a tripod -- this photo only managed to turn out semi-decent due to the strategic use of my roof as a steady base.
And finally, even though the majority of this post is dedicated to birds, it wouldn't be right to publish this without a single bird photo.

Eastern Phoebe

Don Henise found this yesterday, which is pretty early for this species.  Spring is here!

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