It’s easy to find warblers in the guidebooks. In my Sibley’s edition, the warbler section covers pages 328 through 354. It’s a little harder to find them in the field. The key is knowing where to look.
Maine is an impressive place to bird with so many different habitats. The state is smack dab in the middle of the temperate zone. There are forests dominated by both deciduous and coniferous trees. There are marshes, freshwater and salty. There are myriad wetlands.
Maine has many warblers, thanks to all this habitat variation. On a lark, I ranked all 26 nesting species from most to least commonly reported. I used data from eBird, the free database app from the Cornell Lab of Ornithology. Naturally, warblers that use the most abundant habitats are the most abundant warblers.
Bushes are everywhere. Therefore, so are common yellowthroats, the number one reported species. Most warblers take to the trees, but these little tykes nest low, anywhere there is brush. Birders report sightings from manicured southern Maine backyards to northern logging roads.
Likewise, ovenbirds are everywhere. This ground-dwelling bird is the second-most reported warbler in Maine. It typically resides just inside the edge of the forest, and it is more frequently heard than seen.
Tied for third place: northern parula and black-throated green warbler. Neither of these warblers is picky about its treetop preferences. They’re comfortable in both hardwood and mixed forests. Since Maine is the most forested state in the nation, we have a lot of treetops.
Along with all those treetops, we also have a lot of forest edges, which are home to American redstarts and black-and-white warblers. Both like sunshine more than lurking deep in the woods. Both species are plentiful. Neither has been hard to find this spring.
No bird loves sunshine more than the yellow warbler, the seventh-most reported warbler in Maine. It haunts open fields, parks, orchards, marshes and golf courses. It wouldn’t be caught dead in the woods.
Keep the sunshine, but add a few more low trees, and chestnut-sided warblers are apt to keep the yellow warblers company. They avoid the deep woods and aren’t fond of tall trees. Maybe all the warblers topping this list are frequently reported because they sing so much. This one does, too.
The yellow-rumped warbler is probably more common than its number nine ranking suggests, but its song is wimpy and it likes to hide in the foliage. It’s often overlooked, despite its abundance throughout Maine.
Pine warblers are also overlooked, mostly because they rarely drop down from the tops of pines, where they are often heard but seldom seen. They are also widespread across the state, but their numbers dwindle in northern Maine because tall pines are less common.
Conversely, observations of the 11th-most reported warbler increase as you go north. Magnolia warblers liven up the sunny edges of mixed conifer-hardwood forest, the more mixed the better. They avoid the treetops but have an annoying habit of singing just out of sight.
Each of these 11 warblers appeared on at least 10 percent of the Maine checklists submitted to eBird over the last five breeding seasons. The remaining 15 are more difficult.
Some are tough because they are specialists. Black-throated blue warblers (12) are closely related to black-throated green warblers, but they require bigger woodlots, with a strong preference for birch and beech. Canada warblers (15) and northern waterthrushes (16) nest in inaccessible wet areas where they are easy to hear, harder to see.
Blackburnian warblers (14) stay in the tallest treetops and sing weak songs. They’re common, but easy to miss. Palm warblers (19) love bogs. Blackpolls (17) love mountaintops, or anywhere spruce trees are densely packed. Mourning warblers (20) like regenerating clearcuts filled with brambles, mostly in northern and western Maine.
Some birds are northern forest specialists, requiring extensive stands of spruce. These include bay-breasted warblers (21), Cape May warblers (22), Wilson’s warblers (23) and Tennessee warblers (24). Maine populations of these specialists rise and fall with spruce budworm infestations, a favorite food. Nashville warblers (13) are more widespread but are easier to find north of Bangor.
Three species reach the northern limit of their ranges here. I’ve only seen one Louisiana waterthrush (25) and one Blue-winged warbler (26) in Maine, both well below Augusta. Prairie warblers (18) are becoming more common, but are still seldom reported north of central Maine.
The point is, Maine has a lot of warblers. Some are easy to find. Locating others requires an understanding of habits and habitats.
But let’s see another state match our abundance!
