Wednesday, July 23, 2014

Robber flies

Robber fly eating a small white moth
I've had the fortune of seeing quite a few robber flies this year (I first discovered these guys two summers ago). Though seemingly nondescript, they're among the most gruesome of all predators. Relying on surprise, robber - or assassin - flies, lay in wait for an unsuspecting prey to come along and then ambush them, taking the insect out of midair.

Butterflies, moths, and many other nectar-loving insects have long, spindly and bendy proboscises. Not so the robber fly, whose short and hard proboscis is thrust into the body of their prey. It's hard to make out in the photo, but they have a bristly mustache on their face that is potentially a face mask that protects them as their prey flails about.

Then like a shrew, they inject the unfortunate insect with a neurotoxin that paralyzes it and, like a sea star or spider, follows up with an enzyme that liquefies the prey's innards. From there, they make an easy job of slurping up the slurry of guts.

Friday, July 18, 2014

Peregrines at Rock Point

On April 6, I wrote an email to the Vermont Bird Listserv:
I was out at Rock Point yesterday afternoon when I heard a peregrine falcon! This was exciting enough, but it got even better. I watched it fly out over Apple Tree Bay a couple of times before returning to the cliffs below where we were perched. We then watched it swoop out and hover low and fast over the ice about a half mile out to the fracture line in the ice. Along the fracture (which runs from Lone Rock Point out to Appletree Point) there are a few gaps that have open water.
When the falcon got out to the fracture line it landed and we realized that there was already another peregrine out there. They seemed to be watching the open water, maybe for fish in search of higher oxygen concentration? After a few minutes the same falcon took off and flew back directly towards us, it got to the cliff where we were sitting and started to land before it noticed us. It turned and flew back to the ice, mounted the other bird, mated awkwardly while she slipped on the ice, then flew back about 4 seconds later, as is the economy of mating in birds, before landing at the thrust fault. It continued to shriek, and make return visits to the icy (though never mounted the other bird) for about an hour.

Over the past few months we've been able to watch from a distance the peregrines nest building, hunting off the cliffs, carrying food back to the nest, and now successfully fledging two young falcons! The young are easily distinguished by their incessant screeching and begging. I was able to photograph the dramatic playing of the young as they half-heartedly swooped down at a family of mallards at Mink Bay.