This is seriously the season of birdy babies in my neighborhood. I’m seeing and hearing them out in the fields, on the beach, in the woods and in my yard. One measure of the level of activity is how fast the seed and suet are getting used up. Informally, we were going from half a scoop a day a month ago to 4 scoops a day of black oil sunflower seed now — and that pretty much fills up our mesh No/No 5-pound capacity feeder. Good thing we buy seed in 50# bags! We don’t mind the rate of use of seed right now because soon enough we’ll be back to a scoop a day at most. All this seed going out means the local birds are getting a good start, and from my perspective that helps make up for all the problems we humans cause that threatens their survival, from lack of habitat to insect decline to window strikes to outdoor cats….you get the picture. Re window strikes: we rarely have them because our feeders are only a foot away from the window, with the roof of the greenhouse below. According to Audubon that lessens strikes since birds are already flying slowly, on approach to the feeder and departing it. The death zone for feeder placement is 5-15 feet from a wall or window.
Lately we’ve been seeing House finches, Purple finches, Chestnut-backed chickadees, Red-breasted nuthatches, Starlings, Red-winged blackbirds, Pine Siskins, Red Crossbills, House Sparrows, Black-headed grosbeaks, Hairy woodpeckers and Northern Flickers at the feeders, parents &/or kids. Other baby activity evident farther afield but that might be good for a separate edition of the Dawn Chorus.
The staging areas for the feeders are the plum and eucalyptus trees on either corner of this end of the house and the rope across the greenhouse roof (used to tie down the eucalyptus). Birds fly to and fro from stands of firs, pines, alders and willows a bit further from the house. That’s where the invisible nests are.
I can’t keep track of the birdy baby batches for most of them because there are quite a few adults of each kind and there’s no way to tell which fledglings belong to which parents.
Except, I think, for the Red Crossbills! Luckily we have a pair nesting nearby this year. They don’t always hang around long enough for that and some years I don’t see any at all. If they do come through it’s only sometime between April and August. Crossbills are one of my very favorite birds — not just how gorgeous their subtly mottled intensely colored plumage is but also for their calm self-possessed almost philosophical demeanor. Since I’ve only seen one adult male and female crossbill, and in the past when there were more than one many parked themselves at the feeder at once, I’m assuming there’s just one family now.
Here’s what I’ve been seeing so far amongst the fledglings, using information from my photo date stamps and my eBird submissions.
May 14
One male, one female, one fledgling. Fledgling was very young, just hanging onto the feeder, watching parents. This was the only day I’ve seen the female.
May 25
One male, 4 fledglings. The babies had been calling out nonstop all day long from the moment we put the feeder out in the morning for a week by now, mostly watching dad anxiously and getting into a frenzy when he was ready to feed them. At first I thought he was just ignoring them and feeding himself, but no, he was packing his crop steadily, all day long.
Short video of activity at the birdfeeder at this stage:
May 28
One male, 4 fledglings starting to break open seeds themselves from the tray.
May 29
Some working at seed steadily in lower tray, others still crowding around dad up on mesh. They'd been watching and learning. Some were figuring out how to get the seeds through the mesh. Unlike all the other birds (except grosbeaks) crossbills can’t fit their beak through the mesh. The trick is to insert their tongue through, stick a seed to it and draw it out.
Getting a seed AND cracking it open AND holding onto the kernel is a steep learning curve.
June 1
Most are able to extract seed from mesh, still working on full maneuver. But mostly not crying out anymore. Still following dad around.
June 2
By a week ago I wasn’t hearing begging calls from any baby crossbills and now they are mostly on the feeder or on the deck below whether dad’s there or not. I haven’t seen all four at once for over a week. They are husking successfully, eating steadily. Often there’s only one or two visible from the window.
These four seem well on the way to independence. I can’t be sure they are all still around since most of the action, by all the crossbills, is away from the feeder.
According to Birds of North America, foraging in nature for Red Crossbills goes like this:
On closed cones, crossbills bite between the overlapping cone scales to form a gap....
Once a gap is formed, crossbills abduct the lower mandible (to the side to which it is crossed) to spread the scales apart....The upper mandible is pushed against the basal scale, widening the gap. The head is often twisted to the side as resistant scales are pried apart. If this does not expose a seed, the mandibles are reached farther into the gap, sometimes in a biting motion, and then laterally abducted.
This process is repeated until a seed can be lifted free by the tongue; often seeds in green closed cones need to be dislodged with a hooking motion of the upper mandible.
The woody seed coat is removed before the kernel is swallowed. The seed coat is cracked and removed (i.e., husked) by the lower mandible while the tongue helps secure the seed against a lateral groove in the horny palate.
Empty seeds are dropped almost instantaneously; probably less than 1 of every 1,000 full seeds is dropped accidentally. Mechanical considerations and observations of foraging crossbills reveal that the seed is secured in the lateral groove on the side opposite to which the lower mandible crosses.
Red Crossbills are unusual among bird species in that there are as many as 11 different subspecies (depending on who you read) that are distinctly different both in the sound of their call and in their beak shape. The latter is a match for a particular kind of conifer tree. The Crossbills in my area are Type 4, specializing in Douglas fir cones. That means the beaks have coevolved with Doug firs so that not only can they extract the seeds but they can crack them with maximum efficiency.
Why do Crossbills have crossed bills?
Crossbills have crossed mandibles presumably because slender tips are needed to slide efficiently between closed scales and strongly decurved upper and recurved lower mandibles can withstand (and exert) strong forces at the tip of the mandibles (compression forces). If the mandibles were straight and pointed, the shearing forces could cause the slender mandibles to break near the tip.
How fast can Crossbill extract, husk and swallow seeds? Lightning fast. One study in Russia estimated a daily intake of 2,100 spruce seeds. They can store 300 seeds in their crop for feeding nestlings or going to roost.
Breeding information that provides clues as to what I’ve been seeing: (source: Birds of North America birdsna.org/...)
Nest is built entirely by the female.
Crossbills can nest both in spring, feeding on cones that opened over the winter, and in late summer, feeding on newly matured cones of the current year.
They typically lay 3 eggs, sometimes 2 or 4. Larger clutches correspond to a good cone crop.
Only the female incubates, over a period about 2 weeks.
The eggs hatch within a day or two of each other.
Both parents feed nestlings regurgitated kernels and fluid.
Only the female broods the nestlings, who start getting feathers in a week and fledge at about 3 weeks.
For the first week, fledglings wait in trees to be fed. After that they are able to fly pretty well and will follow parents around closely, who will continue feeding them for a month.
Male parent feeds them alone if the female lays a second clutch.
Fledglings gradually learn to forage and make the full transition to independence when their bills have crossed completely. Baby crossbills at hatching do not have a crossed bill.
Since I haven’t seen the female in over three weeks, I thought maybe she’s been incubating another clutch. They’d have hatched by now but still in the nest. Might dad be stocking up on hulled seed now to haul back to the new nestlings? I’m anxiously awaiting a sighting of the female, and maybe even another set of noisy fledglings. It’s quite cacophonous but I like the sound of all that life.
There’s plenty of Douglas fir cones in the surroundings trees — gazillions. The crossbills have lots of food available. But perhaps having this feeder available with its endless supply of sunflower seed the crossbill pair was encouraged to have a second set of babies. The more the merrier!
Are you seeing baby birdies in your neighborhood these days? Do you use feeders?
What birdy action have you been seeing this week?