Today I’m sharing three incidents of birds chasing other birds that I saw these past few weeks, and hoping to get some insights into two of them from folks more knowledgeable than me!
Chase #1
May 26
The first one was pretty clear: blackbirds chasing a raven. Alerted by a chattering sound overhead I looked up to see a Brewers blackbird divebombing a raven.
Small birds driving a larger away from an area is generally described as territorial defense by nesting birds. Interestingly, a week or so after this, a nestful of raven chicks fledged in this same area, which means this raven may have been tending a nest too.
Chase #2
June 11
I noticed this incident when a Turkey vulture swooped right over my head. That got my attention!
There were three vultures flitting around at first. A bit hard to see against the trees but in a pyramid configuration, the top and right corner birds were interacting, while the left corner vulture peeled off and away.
This was the most inexplicable chase to me. I’ve watched a lot of vultures over the years and they are notably polite birds. It’s like they’re Canadian. Even when there’s several working on a carcass they mostly take turns, queuing up. Some minor scuffling but remarkably courteous patient birds. So this was a surprise, looked quite aggressive.
The research I did turned up one possibility: a courting behavior known as the Follow Flight, which I gather is a courtship display. From Birds of North America:
Male and female often sit together at nest site for several days to several weeks before laying. Follow Flight performed by known mated pairs near nests, and during preroost flight by mated pairs and by birds of unknown relationship: 1 bird flies 20–50 m (range 2–200) behind and often above the other; when following closely, the trailing bird may mimic the leader's twists and turns. Most Follow Flights (63%) are of short duration (≤1 min, n = 67). Sometimes repeated for up to 3 h. Flapping more prevalent than during normal flight. In one Texas pair, female was in lead 82% of flights (n = 28). Pairs sometime leave communal roost together after sunset and perform Follow Flight until after dark. Follow Flight performed much more often in spring than in summer or fall.
Trailing bird sometimes dives at lead bird (e.g., in 43% of Follow Flights in Texas). Dive may take form of stylized U-Dive: from 20–200+ m above lead bird, trailing bird folds wings partially and stoops (often nearly vertically) directly toward lead bird; at instant that diving bird arrives, lead bird twists quickly sideways and drops 2–5 m; diving bird then continues upward, following a U-shaped path, apparently without touching the lead bird (or breasts and wings touching; Coles 1938); lead bird continues flying forward.
However vultures start incubating in April and May, so if this was a courtship display mid June is very late.
Anybody else seen this kind of behavior and if so, what time of year?
Chase #3
June 21
This was a group of Northwestern crows, a kind somewhat smaller than the more common American crow, which is the only way I can be pretty sure that’s who they are. Also known as Beach crows, they live and feed mostly along the shore. Their range is limited to coastal Washington state, British Columbia and Alaska.
Even though Beach crows are a distinct species with a limited niche, their social behavior is just like other kinds of crows, the books say. So what we know about crow activity in general would apply to them.
There were several crows first hopping around on the beach, then they flew up to a small grassy rock by the shore. At that point things got really active. Three of them began chasing and divebombing and sneaking up on each other, cartwheeling at times in the air. One other crow stood by, watching them and at times “yelling” at them, caw-ing with its whole body.
The last couple of images are stills from a short video I took of them. It gets across the exuberance and athleticism of these crows better than stills I think. My impression was they were playing.
Then they all stopped, coming to land quietly by the one who’d stayed put. I can hear some kind of other bird call in the video at that moment they all seem to be paying attention to.
Juveniles playing? From the timing it’s likely crows have fledged here now.
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I’d be interested to hear any thoughts about what’s going on with these birds. Behavior is the most fascinating aspect of birds for me and there’s so much I don’t know.
And of course, the Dawn Chorus is now open for your birdy reports of the week.