All across the Northern Hemisphere, birders will be checking their backyards and local nature preserves over the next few weeks, watching for the arrival of summer residents. Some, including tree swallows and eastern phoebes, have been back in the Heartland for a month and others have been trickling in since the beginning of April. Before I left Missouri, a house wren (presumably a male) was already in Columbia, searching our property for suitable nest sites; here in Littleton, Colorado, a lesser goldfinch turned up several days ago, the earliest I have seen one on our farm. But the majority of summer birds will arrive in the coming weeks, joined by a host of migrants that pass through on their way to more northern breeding grounds.
This morning, at South Platte Park, migrants and pure summer residents were rather sparse. Squadrons of tree swallows attacked clouds of midges that rose from the ponds, double-crested cormorants now mingled with the flocks of waterfowl, blue-winged and cinnamon teal cruised the river with their cold-loving, green-winged cousins and a few yellow-rumped warblers foraged in the riparian woodlands; of special note was an osprey that perched on a phone pole along South Platte Reservoir.
It is unlikely that the birds of summer will increase in number or diversity over the next 48 hours. A "spring storm" will arrive this evening and is expected to leave up to six inches of snow by tomorrow afternoon; in concert, the upslope flow will drop our overnight temperature into the low 20s (F). While the Front Range will enjoy an afternoon high of 71 today, tomorrow's high is forecast to be in the 30s, not terribly inviting for our summer insectivores.
