I heard their calls long before I caught sight of them. Their one-note whistles were loud and percussive, and impossible to ignore. They perched high up on bare tree limbs, continuing to chatter amongst themselves. Then, a few scouts came wafting down to the platform feeder I had filled with black-oil sunflower seed. The two ate in peace for several seconds, easily cutting through the shells with their massive bills – bills which are strong enough to crack even a cherry pit. Soon they were joined by the rest of the group.

They presented a gaudy swatch of color amid the muted foliage in the yard. For that I was grateful, but I knew the feeder would be emptied in short order. Evening grosbeaks – “gross-pigs,” as one observer had nicknamed them – are known for their prodigious appetites.

The above-mentioned disgruntled birder was quoted in Scott Weidensaul’s delightful, inspiring, yet sobering “Living on the Wind: Across the Hemisphere with Migratory Birds,” after he had purchased one and a half tons of sunflower seed one winter to keep a flock of 150 pigs – er, birds – fed.

Their outrageous plumage and appetite aren’t the only unusual aspects of this large finch. While other songbirds migrate during the night to take advantage of cooler, less turbulent air, evening grosbeaks migrate during the day, apparently at high altitudes. As documented in the “Birds of North America” species account, in 1964 one female grosbeak crashed through the windshield of a small private plane flying above 6,000 feet.

Additionally, this bird’s name is something of a misnomer. As reported in the BNA account, the person who originally discovered the bird thought it only sang in the evening. But the myth persisted, and the name stuck.

And – speaking of songs -evening grosbeaks are not thought to actually sing at all! The BNA states “the loud, unmusical calls that announce the arrival of a feeding flock of evening grosbeaks…seem to serve most of the species’ communication needs during the breeding season as well. The evening grosbeak seems to be a songbird that doesn’t regularly use songs.”

This bird – although reported to be abundant and widespread – isn’t a regular visitor to backyard feeders either. It is known as an “irruptive” migrant, moving into an area in response to scarcity of food on their breeding territories, and availability of food elsewhere. Their eruptions seem to occur on a cyclic basis, especially coinciding with spruce budworm outbreaks and seed-crop production.

One aspect of their breeding biology is especially interesting in light of last week’s column about the bond between the female purple finch and her injured mate. Ornithologists have reported male evening grosbeaks staying close to female grosbeaks that have been captured for banding. As quoted by the BNA, “some males even venture inside buildings where the mate is being banded, to await her release.”

Perhaps this isn’t devotion as we know it, but who could deny this fascinating aspect of this mysterious, outlandish bird.

NEWS bird columnist Chris Corio can be reached at bdnsports@bangordailynews.net