Bits and pieces

observations of mallard chicks, mosses, and the raven-eagle interface

Sometimes my local peregrinations don’t yield a suggestion for an essay on just one thing. Instead, I get a little scrapbook of unrelated vignettes on various topics. Here is one such scrapbook:

A friend and I were watching a brood of young mallard ducklings on one of the Dredge Lakes. No attendant female was evident for quite some time. Then in flew a female, calling as she descended. Every duckling immediately perked up and, in a bunch, they all rushed over to her, peeping all the way, as if to say, Mama, where were you? We missed you!

This same mallard family was peacefully foraging along the shore a few days later. We heard a sudden ruckus, as the female was loudly protesting something. We peered through the brush and saw a bald eagle swooping down over the ducklings. At each pass, the fuzzy youngsters dove frantically beneath the surface of the pond. The buoyant ducklings popped back up to the surface as soon as the eagle went by. One, two, three passes, and the empty-fisted eagle retired to a tall spruce to rest and reconnoiter. After a few minutes, the eagle tried again, three or four passes, with no luck. Then it gave up. These mallard ducklings were more fortunate than merganser families that can often be seen in Mendenhall Lake. Sometimes eagles wipe out entire broods of unlucky mergansers.

I always enjoy watching ravens in the grocery store parking lots. Perched up on the lamp-posts or along the edge of the roof, they flirt and gossip and groom and wait for a likely-looking pickup truck that might have something interesting and edible in the back. This strategy must pay off fairly often, because the birds keep on watching and investigating. One raven was seen near a local thrift store, where food was not likely to be discovered. But this hopeful (or desperate?) bird was hopping into the open trunk of a car that was merely delivering donations to the store. No rewards there!

Recently I watched a raven, yelling and fussing, chasing an eagle for several minutes. I did not see the outcome of that encounter, but a friend saw a similar interaction, with a visually pleasing (to the observer) outcome. In this case, when the chase was over and the eagle departed, the raven indulged in several barrel rolls and half-twists, in which it was soon joined by another raven, probably its mate. I have to think that the aerobatics were a kind of celebration. Ravens are known to raid eagle nests for the eggs, and now I wonder if eagles reciprocate, trying to snatch raven chicks, causing parental ravens to defend their broods. After all, they were recorded, a few years ago, grabbing heron chicks from the nest.

An uneasy truce? Photo by Jos Bakker

I was reminded, just the other day, of some very interesting and pretty mosses. Most mosses produce dry spores in small capsules that open to let the breezes waft away the spores, to land more or less at random. But some mosses disperse their spores differently, in a way that greatly improves the chances of a spore landing on a patchily distributed substrate that is suitable for germination and growth. These specialized mosses produce sticky spores that do not fly on the wind. Instead, these mosses produce scents from the expanded base of the spore capsule, and the aroma of carrion and decay attracts certain flies that commonly feed on dung or, in some cases, rotting flesh and bones, usually of mammals but sometimes of birds. The flies land, the spores stick to them, and the flies carry the spores to another dung pile, which provides the necessary conditions for the germination of the spores. I’m told that some of these mosses carry specialization one more step: some depend on herbivore dung while others focus on carnivore scat. Making sure that the spores arrive in a good spot is a nifty way to increase the success of your offspring!

Finally, here’s a little mystery. I have observed that robins rototill moss beds, in search of small invertebrates. Ravens and crows sometimes pluck hundreds of tufts of grass and moss from broad reaches of lawns. Mallards grub up square yards of moss and debris, in search of spilled seeds from a bird feeder in early spring. And bears rototill more deeply, in their quest for the roots and stem bases of northern ground cone. But deep in the forest this spring, a friend and I found many places where some creature had scuffled up big patches of leaf litter. Most of these places seemed to be where snow had stayed a bit late and few green shoots were present. This is not good habitat for robins or mallards, and the scuffled places seemed too shallow for bears. The question is Who did it and what were they searching for?

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