Monday, July 18, 2011

Cuckoo for Canaries!

Cuckoos and canaries have very little in common, other than a little alliteration. Both also have common cultural references (he's gone cuckoo, the canary in the coal mine) but I suspect that most people know little about them. Even as a birder, it took me a couple years to see my first cuckoo. Let's take a closer look at these "C" birds.

The brimstone canary (Serinus sulphuratus) is pretty common at ASYV.
It looks very similar to the bird in the picture below, but note that the
above species has a light grey malar stripe that goes to its bill (a
malar stripe is coloration below and behind the bill, above the throat).
It also has an all yellow back and rump.

Canaries eat seeds, and they roam around to find food, often doing so in flocks. It is not behaviors, however, that scientists use to classify most organisms. Structural, cellular, and genetic evidence is looked at to determine where a bird is classified in relation to other birds.

The yellow-fronted canary (Serinus mozambicus) can be distinguished
from the brimstone canary (above) by its black malar stripe that does not
make it all the way to the bill. Its yellow rump contrasts to its brownish
back in flight, and the bills of the two are also noticeably different. 

Canaries are part of a much larger family of birds called "Fringillidae." And although there are no canaries or even Serinus birds in North America, there are similar birds like the house finch, purple finch, and pine siskin, among others.

The Western Citril (Serinus frontalis) is a canary species that visits ASYV.
It, with the African citril and Southern citril, was recently considered
one species. When a body of scientists finds enough evidence, they
may "split" the species into respective species. This split
indicates that Western citrils do not breed with African or Southern
citrils. All three species look slightly different and have different ranges.

What makes a bird a Fringillid then?  According to Don Roberson's Bird Families of the World website, which is a go-to source for exploring bird diversity, birds of the family Fringillidae "have stout conical bills, strong skulls, large jaw muscles, and powerful gizzards. All have modified beaks for holding and shelling seeds. The seed is wedged in a special groove at the side of the palate and crushed by raising the lower jaw onto it."

Not all canaries are yellow. The streaky seedeater, Serinus striolatus, is
found in the highlands of Eastern Africa. "Canary" is an arbitrary
common name that gets its name from the Canary islands.

The differences in birds are one of the things that I love about seeing and studying them. Cuckoos are bigger than canaries, but a more important difference is the structure of their feet. All Passerines (an order of birds in the Domain-Kingdom-Phylum-Class-Order-Family-Genus-Species classification system) which includes the canaries, warblers, flycatchers, sunbirds, hummingbirds, and more than half the world's bird species, have three toes pointing forward and one facing back. Cuckoos have two toes pointing forward and two facing back (which for this and other reasons, places them in a different order, Cuculiformes). This is perhaps something you don't see so well in the field, but it demonstrates how much is going on with birds if you look close enough.

We spotted this red-chested cuckoo, Cuculus solitarius, on a walk down
Lake Mugesera in March.

Cuckoos mainly eat insects. If you look at their bills, they are thin and sharp compared to the thick conical bills of the canaries. These bills are well-suited to snatching caterpillars, moths, and grasshoppers, among other bugs.

Levaillant's cuckoo (Clamator levaillantii) has visited ASYV several times. 

Many cuckoos are brood parasites (about 40% of species worldwide). If a cuckoo species is parasitic, the adult female lays her egg in the nest of another species. The owners of this nest, if they don't reject the egg by destroying it or abandoning the nest, incubate the eggs and then feed the young bird until it has fledged (basically, a fledges when it is able to leave the nest and is no longer dependent on the parents). Sometimes the young cuckoo, directly after hatching, knocks all other objects out of the nest; these other "objects" are either baby birds or other eggs.

A male dideric cuckoo, Chrysococcyx caprius, is electric green on its back
(although it doesn't show in the picture). This bird was feasting upon flying
insects at the edge of Akagera National Park in Rwanda.

Some cuckoos are host-specific, which means they target specific types of birds. Red-chested cuckoos lay their eggs in nests of scrub-robins and robin chats, Levaillant's cuckoos lay in babbler nests, diderik cuckoos lay in weaver nests, and African emerald cuckoos lay in nests of robins and small thrushes.

The African Emerald Cuckoo (Chrysococcyx cupreus) is bright green like
the above dideric cuckoo, but it also has a bright yellow stomach
and green throat. As colorful as it is, this bird was a tough bird
to spot in the highland forests of Ngorongoro Conservation Area.

Despite their negative impacts on their host species, cuckoos make important contributions to the ecosystems. They eat insects (including many caterpillars that decimate leaves) and serve as meals for predators. Interactions between individual species may seem quite cruel, and perhaps they are, but I enjoy overall healthy ecosystems.

The white-browed coucal (Centropus superciliosus) is a different type
 of cuckoo than the previous four. I see this species about every other
day here at ASYV. It is not parasitic like the other cuckoos.
Nearby parent birds sigh relief...

Thanks for reading- I hope you are now cuckoo for canaries!


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