Question 1: How can pigeons sit on concrete and metal even on incredibly hot days? Don’t they ever burn their feet?
Question 2: I once saw a blue jay attack, kill, and partially eat two sparrows within the course of two hours. (I swear this is true.)
Was this aberrant behavior that I just happened to witness? Or was it normal behavior that I had never seen before?
The Cyanocitta stelleri is part of the Corvidae Crow family which is known to…
Oh wait, I’m not Colibri! I always forget!
Ahem
Brace yourself for an incoming annoying nitpick 
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Jillgat: Cyanocitta cristata is the Blue Jay, C. stelleri is the Steller’s Jay. And yes, there is a board that regulates common names in birds :).
Yep, Blue Jays are completely omnivorous, like their close relatives the Crows, Magpies, and Ravens. One stomach content analysis of 292 different birds in 22 states showed about 14% mineral matter ( undigestible pebbles and such ), 24.3% animal matter, and 75.7% vegetable matter. The animals consisted chiefly of invertebrates, but also included various small vertebrates such as fish, salamanders, tree frogs, mice, and birds. They’ll basically take what they can get.
p.s. Jillgat 2: But Colibri is soooo slow 
. Except maybe in Mongol threads - But I haven’t seen that tested yet 
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Oh and I’ll leave question #1 for Colibri, because I have no idea. Might be some fancy countercurrent exchange mechanism I suppose.
Yes, Blue Jays are quite aggressive things. I’ve also seen them enthusiastically dive-bomb cats who were either just nearby minding their own business or actually threatening them.
/minor hijack/ Will most birds attack cats if the birds’ babies are in immediate danger? Jays are the only ones I’ve really noticed doing that. /end minor hijack/
(I went to Nature Camp for like nine years and I’ll be darned if I can remember.)
Creaky: I don’t want to be to universal here, but I think many/most small birds will harass obvious predators if given a chance or at least have a strong motivation. Certainly many/most passerine birds ( or at least the more aggressive ones ) will “mob” avian predators in the air and when they’re perched. I’ve seen nesting House Sparrows, Anna’s Hummingbirds, and Brown Towhees pester cats before in my neighborhood. And I know that most of the blackbirds become quite aggressive during the nesting season. I’ve been whacked in the head a couple of times by male Brewer’s Blackbirds while walking down the street in San Francisco - A very startling experience to say the least 
. And at times the harrassment of predators can be pretty severe…
My Ornithology professor, the sadly deceased Luis Baptista ( a fine man and very entertaining ), said he once did a little informal “mobbing” experiment with a pet owl he had ( I forget what kind ). He tethered it to a stump at the edge of a forest clearing and walked a little ways away to observe what happened. Within minutes hordes of small woodland birds were dive bombing the poor thing. And then to make matters worse, many had been feeding on fruiting berry bushes around the perimeter and they began defecating on the helplessly tethered owl en masse. He said when he retrieved it, it was soaked with partially digested berry juice. Quite an assault .
All that said, I’m sure jays and other corvids in general are much more aggressive than most. Of copurse they tend to get mobbed sometimes, themselves - At least Ravens and Crows.
Tamerlane,
Thank you. I loved birding as a kid and have been thinking of getting back into it. I will probably have some more questions as I go.
Thanks again!
Just to clarify my first post - The contents of all those bird’s stomachs did not add up to 114% . It was the digestible 86% that broke down to roughly three quarters vegetable and one quarter animal.
Creaky: No problem and ask away . But right now I’m off to bed .
I have a large window which, despite my best efforts to put up deterrents, still hs the occasional chickadee crash into it. Recently, one bird hit the glass when a blue jay was not far away. What pursued was a brief aerial dog fight, the jay diving at the chickadee on the wing as the poor bird (who’d had it’s bell rung pretty good and probably just wanted to sit on the deck and clear its head for a couple of minutes) desperately tried to evade and get away (it did). Another 'dee was not so lucky, bounced onto the deck, and a jay flashed down, picked it up in its beak and was gone like that (finger snap). Happy birding all—
Now that others have brought it up… I have seen crows attack baby mockingbirds (small wonder that mockingbird attack crows if they get within 100 feet of the nest); and have seen two mockingbirds fighting with a blue jay; and a huge murder of crows squawking away at an owl that ventured into the suburbs.
Things are especially volatile now, with all the nesting going on. Mockingbirds always nest in the bush in front of my house, and I have to rush past it to my car or risk getting dive-bombed by Mama. Mockingbirds don’t seem to fear anything, no matter the size.
So…any ideas about those incredibly insulated pigeons’ feet?
[[Jillgat: Cyanocitta cristata is the Blue Jay, C. stelleri is the Steller’s Jay.]]
Disculpame! We always called 'em all Blue Jays.
I like to give you people an opportunity to correct me once in awhile…
While I don’t know about pigeons specifically, I believe birds in general have a countercurrent exchange system for blood going to the legs that allows them to tolerate high (or low) temperatures in the feet. The arteries (outgoing) and veins (incoming) run close to one another, allowing transfer of heat. Incoming venous blood that has been overheated can lose some of its heat to the outgoing cooler arterial blood. It’s the same principle that allows gulls to stand directly on ice without freezing their feet or losing too much heat - the feet themselves may be much cooler than the bird’s core body temperature. (And remember a bird’s normal body temperature may be 108 F or higher.)
As for question 1, yeah, Blue Jays are quite omnivorous and, as you have seen, will sometimes catch and eat small birds. They can be pretty devastating nest predators too - in fact, Audubon’s plate in Birds of America shows a pair raiding a nest.
The fact of the matter, Oh Great Khan, is that I HAVE A LIFE! I am not actually on the boards 24/7, like some people seem to be. Honestly, I can’t figure out how you manage to respond to all these bird threads and still keep an iron grip on central Asia.
So that explains why you know so much about birds. Yes, I was very saddened to hear of his recent death. I heard him give a truly brilliant keynote address on his work when I attended the American Ornithologists’ Union meetings in St. Louis in 1998.
A life? What’s that?
Impeccable timing for the first ( i.e. luck ) and the proper application of terror for the second .
A great guy, a fine researcher, and a marvelous speaker . Not a very good instructor unfortunately ( except in the field, where he excelled ). He lacked the organization necessary for a technical class, especially when it came to formal labs. Also he tended to focus on issues he was interested in, like behavior, to the detriment of things like anatomy and systematics. Probably it was mostly just a lack of experience - Outside of the occasional little general interest class, he was primarily a museum curator/pure researcher. The only reason I had him as an instructor was that my university was between ornithologists at the time and they asked if he would step in for a semester, which he graciously agreed to do.
Despite those drawbacks I still consider it time well spent . I DID learn a lot.
And it was a crying shame he went so early 
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What an awesome substitute teacher. Wow. I’m sorry he’s gone too.
There have been several interesting points in this thread. Where to start? The poop attack on the tethered owl reminds me of American Magpie (Pica hudsonia) behavior toward Great Horned Owls (Bubo virginianus). Chuck Trost of Idaho State (my own hero and mentor) placed a stuffed owl on snowy ground. The footprints left by magpies were nicely revealing - very close behind the owl and several feet away in front of the owl. Okay, maybe those magpies coming close behind the owl knew they wouldn’t get nailed (owl hadn’t moved, owl didn’t blink, or whatever other cues they may use to decide that it was not a danger). But wait, they also do this to live predators too. Amongst a group of captive magpies, a Northern Harrier (Circus cyaneus) came to sit on the edge of the cage. Male magpies would sidle up to this bop’s tail and give it a tug. The higher up in dominancy one was, the closer to the marshhawk it got. A little “self-aggrandisement” or advertizing by showing how strong/fast/dominant a magpie is at a dangerous game (yes, they can get nailed doing this). So some tail-pulling during mobbing behavior may not only be directed toward moving the predator on, but also toward the elevation of one’s status. Dominancy is central to corvid social behavior.
The countercurrent heat exchange that Colibri describes is spot on. I have a question about it, though. What’s the relationship between blood flow and blood pressure? According to Gill, some petrels can increase the blood flow through their legs to something like 20 times normal to dump excess heat. I assume there is a corresponding increase in blood pressure to increase this flow rate. The reason why I’m asking is that the pigeons and doves that I bleed have such incredible blood pressure that I’m forced from the normal jugular bleeds or brachial nicks to sample from toe nicks. I thinking that pigeons could dump a lot of heat if blood pressure is of any account.