The white-winged crossbill (pictured) and the crimson crossbill have returned to Maine in large numbers this twelvemonth. The finches have uniquely adapted bills that cross near the tip, allowing them to harvest seeds from conifer cones. Credit: Bob Duchesne

They're back. Crossbills were more often than not absent from Maine last winter. I didn't meet a unmarried one, even when I went looking for them in their favorite places. In early June, I started noticing a few. By July, I was hearing them all over the spruce forests west of Baxter State Park.

Crossbills are finches with a uniquely adapted bill. The tips cross, allowing the birds to excerpt seeds from conifer cones. They insert their bills between the cone scales and twist, opening a gap that allows the bird to reach the seed with its tongue.

Crossbills are notorious nomads. They wander until they find a good cone crop. Then they are likely to stay until they've devoured nigh of information technology, whereupon they leave, unlikely to return until a new ingather of cones has matured.

Ii species of crossbill live in Due north America. The white-winged crossbill is spread throughout Canada, and its range often dips into the northern states, especially Maine. It has a smaller bill and dines primarily on the smaller cones of northern spruces. The crimson crossbill has a more southerly distribution, although it also relies on conifer cones. Some of these cones in the western states can be quite large, and some populations of cerise crossbill take evolved larger bills to bargain with them.

Merely wait. There is at present a tertiary species, and therein lies the tale. 2 years ago, biologists adamant that 1 population of crimson crossbills was genetically distinct from all the remainder, and it was declared to be a new species: the Cassia crossbill. Dissimilar other crossbills, this population does not wander. The birds are virtually wholly confined to a minor mountain range in southern Idaho. They take particularly large bills because they feed on the particularly big cones of lodgepole pines.

Until recently, the Cassia crossbill was considered to exist but another type of red crossbill: Blazon nine. Red crossbills accept been problematic for decades. Although they are all superficially similar, in that location is significant regional variation, and these accept been lumped into 11 types.

Type one crossbills generally range along the length of the Appalachians. They have medium-sized bills suitable for the spruce, fir and pine typical of the eastern states. Type i wanders into Maine, only but occasionally.

By contrast, Type 2 crossbills have heavy bills capable of opening the cones of ponderosa pines throughout their habitation range in the west. They practice wander east, especially into New York, but rarely as far as Maine. Type 4 has a medium-sized bill and is mostly at abode in the Pacific Northwest, dining on Douglas fir. Like the others, it can wander all over the country, merely rarely as far as Maine. Type viii is confined near entirely within its Newfoundland home range, where it prefers black bandbox.

And so on. At that place is fifty-fifty a population that lives at the higher elevations of Fundamental America from Mexico to Nicaragua — Type 11.

Type x seems to be the variation that most oft takes up temporary residence in Maine. It is idea to be about at dwelling house among the Sitka spruces of the Pacific Northwest. It has a small- to medium-sized beak suitable for smaller cones. Therefore, it never wanders among the bigger cones of the Rockies, but it makes large incursions through the Great Lakes and into Maine.

Although all of these red crossbills are nearly identical, and they all make "jip-jip" calls while flying and sitting in treetops, the "jip-jips" of each type are slightly unlike from each other. By running the call through a figurer and generating a sonogram — a graphic prototype that represents the song — biologists tin identify which type has arrived in Maine. Birders are encouraged to record red crossbills and email the file to the Cornell Lab of Ornithology for analysis. It's giving scientists the tools to better understand how distinct populations inside a species evolve into new species. And all that is going on in Maine right now.

The white-winged and ruby-red crossbills are back. While upwards in the wood in tardily July, I heard big numbers of both around Nesowadnehunk Lake, though white-wings outnumbered carmine. Over past Umbazooksus Lake, the reds were more than common. More recently, I heard white-winged crossbills in Lubec. And there is a pair of cherry crossbills that has been haunting the treetops of the spruces at Frazer Point on Schoodic Point in Acadia. I suspect they are romantically involved. She seems to recall he'southward only her Type. He thinks she's a perfect 10.

Bob Duchesne serves equally vice president of Maine Audubon'southward Penobscot Valley Chapter. He adult the Maine Birding Trail, with information at mainebirdingtrail.com. He can be reached at duchesne@midmaine.com. More past Bob Duchesne, Adept Birding