articles

May Warbler Waves

They do not really warble, but have high thin phrases which can be learned over time. Do note that some Bostonians pronounce these birds as “wah-blahs”.

Pine Warbler, one of the earlier warblers to arrive

By Peter Alden


Warblers are tiny thin-billed “Avian Butterflies” that migrate from tropical wintering grounds to breed up north in our warmer months. There are several dozen species with colorful males and somewhat colorful females. They do not really warble, but have high thin phrases which can be learned over time. They are very active as they search for protein rich moth caterpillars that devour emerging tree and bush leaves.


Warblers move about rather quickly and often high in trees. You need to learn how to focus binoculars fast and hope for a good look. "Warbler neck" is a medical term for people who stare too long at a high angle searching for these sprites.


Most warblers winter in Mexico, Central America, and the West Indies with some species continuing into the Andes and Amazonia. Going northbound, most cross the Gulf of Mexico from the Yucatan trying to reach the Gulf coast. In April, most are in east Texas and southeastern states with early leaf-out. By May, they move northward in pulses called “Warbler Waves”. They get backed up by rainy or cool weather and headwinds. Once or twice a week they go skyward when warm winds from the southwest direction give them an energy saving tailwind.


As they welcome the dawn they start scanning for a wooded patch to spend the day. They will practice their songs, chase after some insects and sleep during the heat of the day. They may move north the next evening or remain a few days until another tail wind aids their travels. Warblers and other songbirds migrate in a broad front and will grace every town and village in New England. Large concentrations will zero in on urban parks and cemeteries such as Mt Auburn in Cambridge, the Public Gardens in Boston, Swan Point Cemetery in Providence, and especially Central Park in New York City.


As with most migratory songbirds, the males migrate north and arrive at breeding grounds mostly in New England mountains and in Canada a week or more ahead of females. Thus, in late April and first three weeks of May, we see and hear mainly males. Females tend to pass through in the second half of May into early June.


The earliest warblers that typically arrive by late April are the Palm Warbler (low down in waterside bushes), the Pine Warbler (sings like a musical Chipping Sparrow from high in white pines), and the abundant Yellow-rumped Warbler (that sings its jumbled song high in oak trees). A majority of the warblers will be noted in the first half of May. Some, such as Blackpoll and Bay-breasted Warblers, start arriving in the middle of the month.


Enjoy these colorful birds this spring as most have rather duller plumage in their southbound journeys in September. Join us this spring on several Spark Birding walks at Mt Auburn Cemetery, Concord, and Newburyport this May.


Learn About Warblers by taking our Spring Migration in New England Course. Sign up for a birding walk at Mount Auburn Cemetery.


Can you identify the warblers? Mouse over for the answer.