By December, most warbler species have made it to Central and/or South America where they will spend the rest of the Northern Hemisphere’s winter and then return back North to their breeding grounds. I say most warblers because some species like Yellow-rumped Warblers and Orange-crowned Warblers can survive cold temperatures and actually over-winter successfully in parts of the Northeast. Additionally, some other species occasionally end up over-wintering far North of their usual winter territories and attempt to ride out the cold. Of the 40 species of warblers known to be found in Pennsylvania, 20 species have been found during December, January, and February. With Christmas Bird Counts starting up this weekend, I thought I would offer some tips for searching for late warblers, mention some ways to possibly attract winter warblers to your yard, and highlight a few warbler species that could be encountered.
Searching for Winter Warblers:
The key to finding wintering warbler species is to go where the food is. Warblers are insectivores and must find a habitat with plenty of bugs to survive the winter conditions throughout the Northeast. Small patches of habitat surrounded by buildings, houses, parking lots, and other spots that create micro-climates where the temperature stays slightly warmer than the surrounding area are perfect locations to find wintering warblers. The eBird team has already written an excellent and detailed article on urban and suburban micro-climates, but in general these areas typically consist of hedgerows with weeds and brush, near water but otherwise surrounded by highly altered landscapes. The amount of water can vary from a narrow stream that never freezes to a water treatment facility.
Searching field edges, fallow fields, and meadows can also be rewarding. These more natural habitats offer a variety of plant species with an array of insects to feed on as well as being warmed more by sunlight for the majority of the day. Patches of cedars surrounded by meadows and hedgerows can also be productive because they are often on south-facing slopes and have insects and berries for warblers to eat. Oddly, the ‘habitat’ often created in cemeteries can also be good for winter warblers. Sometimes ‘pishing’ to attract birds near you, or to entice secretive birds out of hiding can be beneficial in finding wintering warblers.
Attracting Winter Warblers:
Another productive location for finding winter warblers can be your own backyard! Small habitats between homes can create micro-climates like I mentioned above, but can also be altered to possibly attract warblers during the colder months. Many birders also keep a pretty close eye on the birds in their yards, so spotting an uncommon visitor may be more likely.
Attracting warblers to your yard any time of the year is all about creating natural habitat that offers a variety of food choices and running water. During the winter this is even more important because wintering warblers need lots of access to highly nutritional food in order to survive freezing conditions. Planting meadow species like goldenrods and asters surrounded by Eastern Red Cedars, any native dogwood species, Virginia or Eastern White Pines, and Shagbark Hickory would work together to create a diverse backyard habitat that could provide a lot of hidden insects during the cold months. Turning backyards from cut-grass and maybe a few scattered trees to a more natural habitat is the best thing you can do to attract more birds to your yard in general. Having a small stream in your backyard or offering a small, man-made water feature that never freezes would help to attract wintering warblers as well.
In addition to providing native plants and native insects, you can also attempt to lure winter warblers into your yard using suet, mealworms, or other high-protein bird food. Here is a link to a great article by the Cornell Lab about suet and other foods to offer birds. Mixing mealworms with Wild Birds Unlimited’s Bark Buttercould provide a very good food for wintering warblers, and can just be smeared onto trees around your yard. Oranges and other fruits may also attract a desperate warbler. Keep an extra close watch on your backyard feeders on days during and following harsh weather conditions, which might force winter warblers to visit feeders.
Below is a entertaining video that Andy McGann took of Pennsylvania’s 4th record of Townsend’s Warbler in January 2012. This warbler often fed on suet at a home in Cumberland County, along with the Pine Warbler shown above.
Usual Winter Warblers:
Warblers are obviously uncommon in the Northeast during the winter months, but the following handful of species are found over-wintering most years and are likely to be found on many CBC’s throughout the region.
Yellow-rumped Warbler – The most abundant winter warbler in the Northeast, with sightings throughout the winter and often encountered on CBC’s (eBird range map). This species is fairly common during winter throughout the state, preferring riparian corridors and cedar hillsides. Learning the chip notes of warblers is a great way to track one down during the winter, and the Yellow-rumped has a pretty distinct chip that it gives often. Yellow-rumps are often in small groups and may have other species mixed in with them, they will also readily mix with chickadees and titmice.
Orange-crowned Warbler – This cold-hardy species has been found over-wintering all along the East coast, but is more uncommon than Yellow-rumped and often quite secretive (eBird range map). Look for this species in weedy fields and forest edge, where it forages low through vegetation but often gives a loud chiponce you disturb it.
Common Yellowthroat – Found about as often as Orange-crowned Warblers, a few Common Yellowthroats are often discovered hiding in cattail marshes and other weedy and shrubby areas along the East Coast during winter (eBird range map). Pishing in habitats that look suitable is a good way to get one to pop up into view or at least hear one vocalize.
Palm Warbler – This species is another fairly regular winter warbler (eBird range map). There are two subspecies of Palm Warbler that can be found through the Northeast during winter and are readily identifiable in the field. “Yellow” Palm Warbler (range map) is found slightly less often than “Western” Palm Warbler (range map). Both species prefer more open habitats, where they can often be seen perched on or near the ground, and characteristically bob their tail.
Pine Warbler – This bright warbler is quite cold-hardy and typically over-winters in good numbers up to southern Virginia, but can also be found most winters all along the East Coast (eBird range map). During winter the Pine Warbler can sometimes be found quietly foraging alongside a flock of Yellow-rumped Warblers, but often sticks to pines. This species is perhaps the most likely to be found grabbing suet from backyard feeders, along with the next warbler….
Yellow-throated Warbler – Although only found sporadically during December and January throughout the Northeast, Yellow-throated Warblers attempting to over-winter aren’t too proud to live off peanut butter and suet in someone’s backyard (eBird range map). This species could also be encountered in warm areas near open water.
Ovenbird – Rare but has been found throughout December and January, usually on CBCs in the southeastern portion of the state (eBird range map). Often attracted to backyard feeders or found in dense, brushy areas similar to what they prefer during migration.
Yellow-breasted Chat – The chat can hardly be called a “warbler” but is still very interesting to see during winter (eBird range map). Almost all winter records through the region have been birds found foraging in dense brambles of honeysuckle and other thick brush, often near water.
Vagrant Winter Warblers of PA:
Although finding any of the previously-mentioned warbler species in the Northeast during winter would be awesome, finding a western vagrant or other super rare warbler is what birders live for. Here are a few examples of interesting vagrant warblers of the Northeast.
“Audubon’s” Yellow-rumped Warbler – Hidden among the expected “Myrtle” Yellow-rumps that are typical in the eastern states, the possibility for finding the rarer western subspecies is highest in the winter (eBird range map). This subspecies is best IDed by its yellowish throat (compared to the off-white or white throat of Myrtles) as well as its slightly different chip note.
MacGillivray’s Warbler – This beautiful warbler has been seen in at least 6 states in the Northeast during winter (eBird range map). Pennsylvania is currently hosting its 2nd state record in the ideal example of an urban micro-climate; Highspire Reservoir Park in Middletown.
Black-throated Gray Warbler – Has been found in a few states on the East Coast during winter, typically foraging low in vines and brush or in a juniper or cedar (eBird range map).
Townsend’s Warbler – Increasing reports throughout the Northeast during winter, and often found feeding from suet feeders (eBird range map).
In addition to winter warblers, the tips above can be used to find really any odd passerine during the colder months. Warmer micro-climates and areas with insect or protein-rich food sources create the ideal habitat for finding rare birds. Orioles, tanagers, flycatchers, thrushes, vireos, and many other birds typically thought of as neotropical migrants as well as many vagrants have been found throughout the Northeast during winter. Maybe you’ll find the next one! Good luck on any up-coming Christmas Bird Counts and please comment with any interesting winter warblers that turn up (or have turned up) in your area!
Thanks to Ian Gardner and Andy McGann for additional ideas and help with the sections above. /