Natural Musings: Rayadito Banding/Furnariidae

Thorn-tailed Rayadito, almost fledged

The head investigator here in Chile for the swallows also studies another bird, the Thorn-tailed Rayadito. He has sites all over the country and a couple of them are here on Chiloe. However, he and his two students cannot monitor all of the sites, so I have inherited a few duties at two of them, namely banding, measuring and taking blood samples from all the nestlings. And since there is one swallow nest at the site here (plus one Rayadito, two Plain-mantled Tit-spinetail, and seven House Wren – which we don’t gather data on), I have plenty of time to do the rayaditos. Worldwide, there are only two Rayadito species, the other confined to the Juan Fernandex Islands, far off the coast of Chile.

A nest waiting to be banded - the green feathers are from
Slender-billed Parakeets, a rare Chilean parrot.

Today was the third time to Caulin, a beautiful little village that makes its living collecting seaweed out of the bay and has almost 100 nest boxes set up on a sanctuary (Fundo de los Cisnes – Foundation of the Swans). I ventured out alone this time to locate the last twenty boxes and band whatever babies were in them.

Banding consists of putting a permanent metal ring with a number on it around the bird’s leg, which will remain forever. Scientists and interested amateurs have been doing this for the better part of a century and many, many big discoveries have come out of it, such as migration routes, wintering grounds and site fidelity as well as being able to recognize individual birds in scientific studies of behavior, ecology and evolution. Rayaditos are a tiny little bird, so I use a tiny little band. The Barn Owls that are banded every year on Nantucket (and which a friend is now doing a cool project on) require massive bands with a foldable flange on them so the owls don’t tear them off. But the Rayaditos present no such problems.

Set up workspace, bands, pliers, needles, cotton, capillary tubes, blood paper,
calipers, pesola and vaseline (to move away from vein).

Secondly, I measure various parts of the body – bill, tarsus, wing and tail length plus mass – but because these measurements are not done at a uniform time (i.e. some of the babies might be 12 days old, others 9), I don’t know how much value these measurements are going to be. Then I take a little bit of blood from the brachial vein by pricking it with a needle as it crosses the bird’s shoulder joint – extracting the small drop of blood with a capillary tube. Usually a few seconds of pressure with a piece of cotton stops this – I have never had to use styptic powder (yet). Then the blood is transferred to a storage medium. For swallows, we use a DNA lysis buffer, which breaks up the cells and preserves the DNA, while for the Rayaditos we use a special blotting paper which preserves it.

Adult Rayadito, concerned about its babies.

Then quickly and quietly, I put the babies back in the nest and let the parents have them back. Usually during the entire ordeal, the parents are no more than a foot or two from me, screaming (wouldn’t you be?) and carrying on. A few have even learned to pull leaves off the tree and drop them in my general area, which is both ingenious and entirely ineffective.

They start being obnoxious young.

Rayaditos belong to an interesting family of birds: the furnariids, otherwise known as the ovenbirds. They are of very distant relation to the Ovenbird of North America (a wood-warbler), but are a common group in South America. They get their name from the nest of a few species which looks like a dutch oven (also where the other Ovenbird gets its name) though the majority build stick nests. They take a variety of niches here, the rayadito and tit-spinetails are very chickadee-like, treerunners are like nuthatches, the hornero is similar to a robin/catbird, rushbirds are like marsh wrens and others are quite unlike anything we have here…

A woodcreeper (Red-billed Scythebill). Evolution is weird.

The Rufous Hornero (pictured above) is the national bird of Argentina and a conspicuous bird in the entire northern part of the country. It is probably from this bird's nest that the family derives its name, as the nest is a carefully constructed mud "oven" - and the name of the bird is a derivative of the spanish word for oven, horno.