Orchard Oriole is a small slender oriole that almost suggests a large warbler. It breeds widely across the eastern United States and west through the Great Plains and winters from West Mexico to Panama where it feeds mostly on nectar like a honeycreeper or sunbird.
The migration of Orchard Oriole is very interesting, especially when compared to other Neotropical migrants. Is arrival pattern and timing very much mirror that of Baltimore Oriole and many Neotropical migrants. It first appears on the Gulf Coast in late March and in the ensuing weeks of April it progresses northward. It often reaches the northern limits of its range in coastal New Hampshire and southern Maine (occurrence there is too low to show well on these maps) by early May. They begin breeding quite quickly with young off the nest by mid-June. These young hang around for about a month, and then by mid-July the species withdrawals.
The southward movements are particularly interesting because they are so early. Although migration for many warblers begins in August, relatively few landbirds move in large numbers in July. But by late July Orchard Orioles have already arrived in Costa Rica and by mid-August it becomes hard to find one in many of its regular breeding areas (e.g., Massachusetts). In Maryland there are just 20 Orchard Oriole records in eBird for September. Compare this to Baltimore Oriole, which remains a common migrant throughout September and well into October. Orchard Orioles in North America after October 1 are extreme rarities. At that season most records are from California (where the species is always rare). Check out the frequency map of Orchard Oriole occurrence from Oct-Dec.
On the wintering grounds Orchard Orioles are very much nectar specialists which perhaps explains their extreme rarity in the East after early September. Few other Neotropical migrants withdraw so early and so completely from the continent, but Louisiana Waterthrush is one other example. Louisiana Waterthrush seem to arrive extra early to rear their young, arriving at the northern reaches of their range by mid-April, much earlier than other Neotropical migrant warblers. Their withdrawal is as early and as complete as Orchard Oriole, with arrivals in Mexico and Belize by early July and even late June. Like Orchard Oriole, it becomes a rare bird in the United States after 31 August.
Active landbird migration in July is something that few birders go looking for, and it is one of the phenomena that we hope to understand better through eBird. Next time you are birding in July, keep an eye out for southbound migrant landbirds!
[Note: At least one region that the eBird models is overly ambitious is apparent: Orchard Orioles are not regular away from extreme eastern New Mexico and certainly do not regularly occur in Arizona in summer.]