Migratory birds are heading north – the dogs and I flushed a small group of mallards this morning from a vernal pool (vernal lake is more like it) across the street. Two interesting bits of songbird migration info have come over the transom in the past couple days. First, check out this excellent post on songbirds, coffee and the World Bank from the Terrierman (I’m sure many of my visitors also check Patrick’s blog, but if you don’t here’s a reason why you should). Second – via NPR on the drive in this morning – greater noctule bats (Nyctalus lasiopterus) are occupying an unexpected niche – preying on migrating birds as they come north through Europe.

The ability of giant noctules to prey on the wing upon nocturnally migrating passerines appears unique not only among bats but also within the whole animal kingdom. Although carnivorous bats feeding on small-sized vertebrates are not rare, they all live in the Tropics and collect their prey from substrates. The few species of falcons which capture migratory birds along the Mediterranean and African coasts are exclusively diurnal. Finally, owls, as typical night-active predators, never forage in the open space: moving prey is detected from substrates through passive-listening of rustling noises. *

Here’s a link to the paper that is causing the hubbub – right now it looks like the Public Library of Science servers are getting slammed, but when they come back up I’ll likely post an addendum.

From: Figure 1 of Popa-Lisseanu, A. G., Delgado-Huertas, A., Forero, M. G., Rodriguez, A., Arlettaz, R. & Ibanez, C. 2007. Bats’ conquest of a formidable foraging niche: the myriads of nocturnally migrating songbirds. PLoS ONE 2(2): e205.

I just got back in from airing out the dogs in the woods behind my house. We’d gotten about 20 yards deep in the woods (see snow pictures below for an idea of what I’m talking about) when 2 birds flew toward me – moved by the dogs I think – and perched between me and the dogs, who were a ways in front. At first, I thought they were crows (based on their size), but when they perched, I knew that wasn’t the case – typical raptor posture, and the one I had the best view of had his head low and out in front. The sky is overcast and the light is poor, so I didn’t pick up much more than silhouettes. They were calling to each other – one would krek and the other would reply: krek-krek (think of the sound of trees creaking in an otherwise quiet wood). They stayed perched for a heart-stopping 35 seconds or so, then flew off – under the canopy. I know what I think they are, but I’d appreciate a reality check/wishful thinking alert. I know a pair of what-I-hope-they-are nests about a half mile south of the house (though I can never find the current year’s nest). There was some logging last year where they normally nest – maybe they’ve been pushed towards me?

Later – I realize there’s not a lot of data to go on – it’s really the calling that I was curious about – whether that was enough to rule anything out or in.

I received a picture today of a couple dart frogs (D. tinctorius Surinam Cobalt) I sold to a local frogger last fall. He was just getting started in the hobby – I’d say he’s off to a very good start. We both think he got a male and a female; males tend to have larger, heart-shaped front toe pads. I’m grinning like a Cheshire cat…

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