If birds ever observed their human neighbors parading around one October night, looking decidedly unlike themselves, and wanted to celebrate their own version of Halloween, some could hide their identity with little effort. Below are five examples of ways one bird can look like another, given their existing similarities:

Blackpoll Warbler -> Bay-breasted Warbler

Perhaps not surprisingly, some birds of the same genus look nearly identical to each other. During the fall, a nonbreeding male, female, or juvenile Blackpoll Warbler hardly needs to do anything to make people believe it’s a Bay-breasted Warbler. With the two sharing similar coloration and size, unsure birders may mark what they spot as a ‘Baypoll’. But if a Blackpoll Warbler wants to go all in, it can do the following: 1) add a hint of bay (or reddish-brown) to its flanks, and remove the blurry, dull-green streaking from its flanks and upper breast; 2) remove any yellow on its legs, feet and toe pads. Bay-breasted Warblers have grayish or blackish legs and feet, and sometimes pinkish toe pads; 3) Change head and upper back feathers from an olive green to a more yellowish green; 4) Adjust the tint of its whitish-colored breast feathers from a lemon-yellow to a buffy-yellow; 5) Make the lower mandible more pinkish instead of yellowish. These changes should ensure that the Blackpoll is successfully disguised before it feasts on treats such as insects and berries – perhaps not so coincidentally, fare that its lookalike also enjoys.

*Blackpoll Warbler in Fall Plumage*
*Donna Dewhurst - U.S. Fish and Wildlife Service*
*Wikimedia Commons*

*Bay-breasted Warbler, Monhegan Island, Maine*
*Diana Stephens/Audubon Photography Awards*

Downy Woodpecker -> Hairy Woodpecker

If you see adult Downy Woodpeckers and Hairy Woodpeckers together, you might assume that they are close cousins; after all, these two species are so similar looking, with a white body, black and white head and wings, and – at least for the adult males - a red patch on the back of their head. Juveniles also look alike; here, the young males have a red spot on the top of their head and not the back of it - note that for a Hairy, this patch might be yellow instead of red. But these woodpeckers are actually not closely related; about 6.5 million years ago, their genetic lineages diverged from a common ancestor. This plumage mimicry may have occurred because Downy Woodpeckers and Hairy Woodpeckers share a wide range of habitat, and there is potential benefit for the former to look like the latter. Research has suggested that Hairys are more dominant than their relative, although this needs to be studied further.

At any rate, the Downy Woodpecker is smaller - so if they want to really masquerade as the other bird, they need to make themselves look longer by 2-3 inches. One is around 6.5 inches, the other 9.25 inches. Downys also need to elongate their bill and remove the black spots/bars on their white outer tail feathers. With regard to that red patch, male Hairys often have it split vertically down the middle by a black strip. As a bonus, the littler woodpecker could change its call from a quick ‘pik’ to a more assertive ‘peek’. As far as where to find treats, a Downy may come to your house – assuming you have a feeder of suet and sunflower seeds. Since Hairy Woodpeckers also visit feeders, there’d be no reason not to stop by.

*Downy Woodpecker*
*Nick Shearman/Audubon Photography Awards*

*Blue Jay and Hairy Woodpecker, Shiocton, Wisconsin*
*Marie Schmidt/Audubon Photography Awards*

Pine Warbler -> Yellow-throated Vireo

Sometimes birds that are not even of the same family can pass as each other. From a distance adult Pine Warblers, of the New World Warblers, could be confused with adult Yellow-throated Vireos, part of Vireos, Shrike-Babblers, and Erpornis, as they are around the same length with similar patterns of white, gray, and yellow splashed across their feathers. Both birds have a yellow throat (although only one is named for that), a yellow breast, and white wingbars. More work needs to be put in, however, for a successful ruse.

The bill of the Pine Warbler lacks the distinctive hook of the vireo, and it typically has blurry streaking on its sides and/or breast while the vireo does not. The back, scapulars, and rump of the warbler are olive, while the Yellow-throated Vireo has an olive mantle that morphs into a slate gray lower back, scapulars, and rump. The tertial feathers also need to be considered; the warbler’s tertials have a dark gray center outlined by light gray, while those of the vireo are darker gray with wide white edges. The latter’s tail feathers also have white edges, whereas the warbler’s are not defined that way. This wood-warbler has a yellow eye ring connected to a yellowish supraloral; with a similar eye ring but a yellow loral instead, the vireo has a more bespectacled appearance. Interestingly, it has blue feet, which the warbler should emulate. After making the necessary modifications, the Pine Warbler should be ready to scarf down food they both enjoy: insects, fruit, and seeds.

*Pine Warbler, New Orleans, Louisiana*
*Lisa Gambino Plaia/Audubon Photography Awards*

*Yellow-throated Vireo. Rondeau Provincial Park, Ontario, Canada.*
*Mdf*
*Wikimedia Commons*

Female Purple Finch -> Female Rose-breasted Grosbeak

While adult male Rose-breasted Grosbeaks and Purple Finches are noticeably different, their female counterparts may be able to disguise themselves as the other with a bit of ingenuity. It would probably be easier for the Purple Finch, which has a thinner, gray beak. The grosbeak has a thick, pinkish, nearly equilateral triangle-esque beak, and it would be pretty impossible to pare it down. Additionally, the grosbeak is larger (7-8 inches vs. 4.5-6.5 inches), so the finch would need to bulk itself up.

The colors that dominate both are brown and white; while the head of the finch is brown with streaks of white, including one stripe that runs from the top of the eye to the nape, the grosbeak has a prominent white eye stripe that runs from right before the eye to near the neck. This eye stripe would need to be added for a convincing costume. There are thicker streaks of brown on the body of the finch, while the brown streaks are thinner on the grosbeak’s sides, chest, and flanks, and the lower belly is mostly white. Grosbeaks also have two white wingbars while finches have nondescript markings. Although Purple Finches primarily eat seeds, they will also consume other food items such as berries, which is what Rose-breasted Grosbeaks mainly feed on during fall migration.

*Purple Finch (Carpodacus purpureus) female, Cap Tourmente National Wildlife Area, Quebec, Canada.*
*Simon Pierre Barrette (Cephas)*
*Wikimedia Commons*

*Rose-breasted Grosbeak, female, Florida Lake, Cumberland county, Maine*
*Dana Greindl/Audubon Photography Awards*

Wood Duck Duckling -> Mallard Duckling

Young chicks should also be able to enjoy Halloween, although most will be too old by the time October 31st rolls around to take advantage of their hatchling or fledging plumage. If there were a similar version in the summer, a young Wood Duck, with a little creativity, could blend into the family of another waterfowl - the Mallard. Arguably the most noticeable difference between the two duckling types is the eye stripe. A Wood Duck has a black bar that runs from the back end of each eye to the back of the head; for a Mallard, that stripe ends in the same place but starts at the beak, before the eye.

Not only does the Wood Duck then need to elongate this stripe, but it must find a way to make itself look larger, asMallardsare the bigger birds. Additionally, it should be prepared for when something scary happens; if a Wood Duck mother is escorting her children and feels threatened, she will fly away to circle the area or roost in a tree and return once the danger has passed. In a similar situation, Mallard mothers stay with their brood and look for a safer locale. Time spent trick-or-treating should be fun though, as the two waterbirds enjoy similar fare such as insects and other invertebrates.

*Wood Duck, chick, Juanita Bay Park, Kirkland, Washington*
*Mick Thompson*

*Mallard, chicks, Texas*
*Karin Saucedo/Audubon Photography Awards*

Just some ideas for a select few birds (if they ever read this). But honestly, if you go birding and you see one, some, or all of these species, I hope you don’t get tricked!

Sources:

Blackpoll Warbler -> Bay-breasted Warbler

Identifying Bay-breasted and Blackpoll Warblers - eBird

Blackpoll Warbler | State of Tennessee, Wildlife Resources Agency

Bay-breasted Warbler | Audubon Field Guide

Blackpoll Warbler | Audubon Field Guide

Downy Woodpecker -> Hairy Woodpecker

Are Woodpeckers Evolving to Look Like Each Other? A New Study Says Yes

Tricky Bird ID: Downy Woodpecker and Hairy Woodpecker - FeederWatch

Downy vs Hairy Woodpecker: Here's How to Tell The Difference - BirdWatching

How to Tell a Hairy Woodpecker From a Downy Woodpecker | Audubon

Birds of a Feather, They're Not | The Outside Story