Jul 30, 2017
by Lisa Hug
Most people associate Black-headed Grosbeaks with spring, when their beautiful song awakens us to freshness of new things to come. But I often think about them in August. This is when they try to slip out of our northern lands and drop down to Mexico without being noticed. I always try to catch glimpses of them quietly lurking in the streamside willow forests before they leave. I just don’t want them to leave “without saying good-bye.”
There are many things to appreciate about Black-headed Grosbeaks. For one thing, the name literally means “big bill.” And their bill is massive. It is designed to tackle large seeds and hard-bodied insects. But, that is not generally the first thing we notice about this bird. It is very colorful. It has striking patterns of orange and black with white checkering and subtle yellow highlights. But, even with this strikingly bold appearance, we usually find Black-headed Grosbeaks by hearing their ornate songs first.
Black-headed Grosbeaks are neotropical migrants. This means they spend most of their time (about 7 to 8 months) in the new world tropics, in this case – Mexico. They migrate north to the temperate areas of western North America during spring and summer to breed. This is when we get to see and hear them.
Avid birdwatchers start anticipating the grosbeaks arrival in mid-March, but they usually don’t arrive until the first week in April. The adult males arrive first. They busy themselves singing enthusiastically to establish suitable territories to share with a mate. The females arrive about 4 days later. They often choose their mates within 3 to 5 hours of arrival. It is unclear whether they are choosing the handsome male himself, or the luscious territory he established. When all the territories of the nesting pairs are set up, the young yearling males arrive. These yearling males do not get mates and they are watched closely by the older males.
The adult male’s song is beautiful. It is a series of phrases, separated by pauses. The phrases loop upward, then downward, much like a robin’s song. However, the grosbeak sings a little faster than a robin, with a few more ornamentations. He will often sing from the nest itself. The female also sings, and also from atop the nest. Her song is very similar to the males, but a little shorter and less ornate. Both the males and females share the daytime duties of rearing the eggs and nestlings equally. But only the female will sit on the eggs at night. Her belly has a “brood patch” which is a featherless, highly vascular area of skin which provides warmth for eggs and nestlings.
Young grosbeaks are fed lots of insects. Two examples of insects in their diet are California oak moths and codling moths. The adults will eat some cultivated fruit, but the damage is more than offset by the huge numbers of pest insects they consume and feed to their young.
Once the young become fledglings and can move through the forest, they develop their own short vocabulary -a strange ‘whee-oo” call. As you may have guessed, this sound means “feed me, I’m right here.” Grosbeak families are typically very noisy as the youngsters make these strange sounds and the parents constantly sing and “chip” to keep in contact with each other.
But then late summer arrives and the grosbeaks are suddenly quiet. The young have all grown and the parents have no more need to keep in contact with each other. The breeding season is over. It feels like grosbeaks no longer exist. But there is something magical about catching a silent glimpse of a grosbeak foraging in the forest just before it starts its return journey to Mexico for the winter. I always want to say “bon voyage“ and “hasta la vista.”
Black-headed Grosbeaks will come to seed feeders (be sure to keep these feeders clean, occasionally cleaning them with dilute bleach solutions). Two places to see these birds in the wild are the Santa Rosa Creek Trail off Willowside Road and Ragle Ranch Regional Park in Sebastopol. But, don’t delay; they may all be gone by September
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