Late Spring Migration

By John Pogacnik, Biologist

To many, Memorial Day Weekend signals the end of spring migration. The brightly colored male warblers have passed through, new leaves on trees make it difficult to see birds, and the huge number of migrants have dwindled down. Birders have waited all year for spring migration, but many have already put their gear away and started dreaming of next year. Don't put those binoculars away yet--there is actually still a lot to see! There are still stragglers out there--warblers, thrushes and flycatchers can sometimes be seen as late as mid-June.

The last week of May and the first few days of June bring in female and immature warblers, thrushes, vireos and it is the peak time for migrating flycatchers. If you get out on a good day with south winds, it is often possible to see all ten species of the regular migrating flycatchers. This is the best time to see yellow-bellied, alder and olive-sided. This time can also bring large numbers of gray-cheeked and hermit thrushes. Get out at sunrise and listen. I have heard dozens of thrushes calling and an hour later they are hard to find. Learn their call notes and you’ll find a lot more. This time of year is also good for red-eyed and Philadelphia vireos. The large numbers of blue jays and American goldfinches are gone, but there are often large flocks of waxwings.

Female chestnut-sided warbler

This is the time for female warblers, but also the males of some of the later migrants such as Canada, Wilson’s, blackpoll, mourning and Connecticut warblers. The Connecticut is often hard to find, but is most common in late May and into June.

A lot of birders find it difficult to see female warblers because they are not as brightly colored as males, they don’t sing and they are hard to find in leaf cover. While that is the case for many species, some actually look identical to the males or look like washed out versions with enough color to make it easy if you know your breeding plumaged males. Birds that appear nearly identical are ovenbird, Louisiana and northern waterthrushes, orange-crowned warbler, Nashville warbler, yellow-throated warbler, palm warbler, worm-eating warbler, Kentucky warbler, Prothonotary warbler and yellow-breasted chat. If you know the male birds, you’ll know the females.

These female birds look like washed out versions of their male counterparts:

• Northern parula (lacks dark necklace)
• Blue-winged warbler (black head markings replaced by gray)
• Golden-winged warbler (black head markings replaced by gray)
• Chestnut-sided warbler (less color)
• Magnolia warbler (paler, watch for the white in the tail)
• Blackburnian warbler (paler orange or yellow throat)
• Yellow-rumped warbler (browner but still has the yellow rump and yellow spots on the sides)
• Yellow warbler (all yellow with very subdued streaking)
• Black-throated green warbler (much less black in the throat)
• Bay-breasted warbler (much more restricted reddish orange on the crown and sides)
• Pine warbler (paler)
• Black and white warbler (white throat and buffy flanks)
• American redstart (black is replaced by brown and the spots are yellow)
• Hooded warbler (if you get a close look at the head, it has an incomplete hood)
• Wilson’s warbler (cap is much reduced)
• Canada warbler (reduced necklace)

Female Blackburnian warbler

The next few females are a bit more confusing as they don’t resemble their male counterparts much (if at all):

• Black-throated blue warbler: does not resemble the male at all. The one field mark to learn is the small rectangle on the wing. Other than that, it’s brownish with a faint eye-stripe.
• Cerulean warbler: somewhat resembles the male, but is bluish-green above, has wingbars and is faintly streaked below. It lacks the necklace of streaks that the male has.
• Cape May warbler: pale yellow and heavily streaked below. It has a similar facial pattern as the male, but lacks the reddish hue.
• Prairie warbler: closely resembles the male, but has much reduced markings. The key here is that it wags its tail.
• Blackpoll warbler: lightly streaked with a very light greenish-gray wash to it. The thing that stands out are the bright yellowish legs and feet.
• Common yellowthroat: lacks the distinct black mask of the male. It is a plain brown on the back, but has the yellow throat.
• Tennessee warbler: yellowish above and white below. It resembles the male, but has a yellowish wash to the head and upper chest.

This leaves us with the mourning and Connecticut warblers. The females of both species closely resemble the males, but their gray hoods are not a clear gray and the mourning lacks the black bib of the male. The confusion here is that some female mourning warblers can have a distinct eye ring. Although the books say it is broken, you occasionally see them with a complete eye ring. The best thing to look for in these is the Connecticut is sluggish and walks around feeding like a waterthrush or ovenbird and the mourning is much more active and hops. The Connecticut also has long undertail coverts that reach fairly close to the tip of the tail and the mourning doesn’t, giving a longer look to the tail.

The key to the females is to not get scared off thinking they are extremely difficult to find. If you take your time looking and remember what the males look like, you can make it a lot easier for yourself and extend your warbler watching for another week or more. You may not be able to identify every one you see, but you should be able to identify most.

The birding forecast

South winds should continue to bring in migrants. A warm front is supposed to move through sometime Sunday and may bring a good movement of birds on Memorial Day. Watch for female warblers and flycatchers, but this time of year can bring stragglers also, so anything is possible.

Recent sightings

A lot of warblers are around, including mourning and Connecticuts. All of the regular appearing flycatchers and both species of cuckoos have been seen. All the breeding birds are back and are on territory. The early breeders are already fledging young.

Female American redstart

Birding at Lake Metroparks
Photos by John Pogacnik, Lake Metroparks Biologist