Friday, September 24, 2010

Why do raptors hate each other?

Large grasslands are good for raptors, especially in September. At the one I work at in Massachusetts, I've seen merlins, kestrels, peregrines, ospreys, Cooper's, red-shoulders, and red-tails all in a single day. And they all seem to hate each other.

Yesterday I saw a peregrine and a Cooper's hawk terrorizing a pair of harriers, which seemed slow and cumbersome in comparison. And they weren't just chasing, but actually making full-speed, talons-forward attacks. The harriers would roll over, talons up, to defend themselves - a common response of larger birds in response to such pestering. But mostly they just seemed to want to be left alone.

It could be a between-species competition thing...or maybe a small bird, large bird thing. But I don't think so. A few years ago (same site, same time of year), I saw a harrier and a peregrine working together, relentlessly attacking a second, perched peregrine (see photos).

Harrier versus peregrine.

Peregrine versus peregrine.

It could be a between-individual competition thing. I'd say it probably is most of the time. A crowded field of hawks, hungry and cranky from migration.

But, intriguingly, it also could be cannibalism of a sort. A common site around the grasslands is merlins (notoriously cranky, even for raptors) swiftly pursuing kestrels in the same "I-want-to-kill-you" way. I've never seen one caught yet, but if I do I won't be surprised.

Harrier wins.

Thursday, September 9, 2010

Mockingbird attitude

Audubon print showing typical mockingbird attitude.

A few weeks ago, in Massachusetts, I saw a black rat snake crossing the road with a mockingbird swooping down at it over and over and over again. This seemed silly. Why would a big snake be scared off by a little mockingbird?

Well, I suppose it could alert a hawk to it's existence...but never mind that. I happen to know that mockingbirds pose a real threat.

A couple years ago, in the Jersey shore town of Lavalette, I heard the telltale ear-splitting whine of mockingbird babies (a mystery in and of itself) coming from a street-side holly bush. I was parting the foliage and peeking in at the nest when...wham!...the parent swooped down and slammed into my arm so hard that it actually hurt! The bird, which I was sure would not survive such a collision, flew to a nearby perch and kept up his/her complaining "check" notes.

A tropical mockingbird...different species, same attitude.

And this turned out not to be an isolated incident.

This summer, in another Jersey shore town (Bay Head), I was simply walking along the sidewalk - not bothering any nests, mind you - when...whoosh!...a mockingbird came down from the wire and grazed my hair! I imagine that I would have been thumped again if I had dared approach its nest.

What's with the attitude?

New Jersey comments aside, I'm guessing that mockingbirds are just juiced up on an abnormal amount of hormones during the breeding season. I have no proof. But they sing all night long. They even sing in flight, as I also observed this summer. And why else would they be ornery enough to perform full-force body-slams into creatures hundreds of times larger than themselves?

Wednesday, September 1, 2010

Chickadees and cherries

Wild black cherry trees are in full fruit these days, and the birds are all over them. I found a good one a few days ago in Lanoka Harbor, NJ. Good in this case = low to the ground, and absolutely loaded with ripe fruit. The "low to the ground" part facilitated nice views of the birds perusing the fruit clusters, and the "loaded" part made the birds crazed enough with food lust that they paid little attention to me. Orioles, titmice, and house finches all picked at the cherries, and a gnatcatcher hopped about, maybe in search of cherry-eating insects. A juvenile chipping sparrow, a female cardinal, and a few robins also made appearances.

But the star of the show (both in numbers and in style) was a flock of about 10 carolina chickadees. Their strange eating style was as follows: pick off a cherry, grasp it between the toes, peck at it for a second, drop it, and move on to the next. I thought maybe they were eating the pit, at first...similar to how sparrows often eat just the seeds of rose hips, spitting out the fruit.

Chickadee, pecking.

But when I downloaded my photos, I found a surprise: a little grub-like creature. My guess is that they were extracting fly larvae, and then spitting out the "useless" fruit and pit which would clog up their guts with empty calories. The amazing thing was how fast they would accomplish this process: pick, peck, drop, repeat.

Chickadee in mid-grub-extraction. Notice the squirt of juice!

As with many great discoveries, I have no proof but a grainy image. It was getting dark, and I didn't have time go cherry-dissecting to find grubs. I did, however, find time to eat a few myself.

Exhibit A. Grainy close-up of a grub-like object in the chickadee's beak.