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Guatemala: Skunkhead Flycatcher

February 23, 2010

One of the most conspicuous bird families in the neotropics are the Tyrant Flycatchers, or to science types, the family Tyrannidae. Tyrant Flycatchers are a family endemic to the Americas, and at different times of the year they can be found the entire reach of the continents, from near the Arctic Circle to Tierra Del Fuego on the southern tip of South America.  They reach their highest diversity in the tropics, especially in the North American winter when most of the migrants have returned to their ancestral homes in Central and South America.  As the largest family of birds on earth, they’re a common sight just about anywhere you can imagine a bird can be, and while we primarily consider flycatchers to be insect eaters, as the name implies, in the neotropics they take advantage of any available food supply, from fruit to fish.

While the myriad Tyrant Flycatchers can generally be separated into manageable groups by genus, there remains a group of birds that look exceptionally similar, sharing the basic pattern of brownish back, yellow front and bold black and white markings on the head.  North American birders are probably familiar with this pattern in the Great Kiskadee (Pitangus sulphuratus), the only member of this group to regularly occur in the ABA area.  Remarkably, though, most of these birds aren’t co-geners, or even really all that closely related despite their copy-cat appearance.  A particularly common example is this Social Flycatcher (Myiozetetes similis), photographed through my binoculars at Bambu Lodge on Lake Atitlan, Guatemala.

The reason for so many unrelated species to show such an obviously similar pattern is still unknown, but it’s unlikely to be a coincidence due to the number of genera and species involved.  It’s suggested that it may be some sort of Batesian Mimicry, in which a smaller species gains some protection by mimicking the warning signs of a harmful species.  Larger species expressing the “Kiskadee pattern”, particularly the widespread Great Kiskadee and Boat-billed Flycatcher, are well known for being extremely aggressive, especially towards raptors.  This attitude may allow the smaller, more docile, birds some element of protection by appearing at first glance to be one of the species no one wants to mess with.

There’s also the possibility that the bright colors warn of something more than just a bad attitude.  In other taxa, bright colors and striking patterns are typically associated with some sort of danger for the potential predator.  Interestingly, the Foxface Rabbitfish of the South Pacific shows a very similar pattern to warn of some serious poisonous barbs in its fins.  It’s been suggested that perhaps the Kiskadee patterned flycatchers have a similar chemical deterrent or are, at the very least, distasteful.  But while tyrant flycatchers are indeed reported to taste bad, not something I was able to verify first hand incidentally, it’s probably not enough to discourage a determined predator and the only truly poisonous birds known in the world are still the Pitohuis of New Guinea.

In any case, the similarity makes for some obvious identification difficulties, as from a distance all of the Kiskadee patterned birds look very similar save for the differences in bill size and the odd subtle differences in the extent and boldness of the facial pattern.  Knowledge of vocalizations is extremely useful too, though for those of us from the temperate zone, something of an overwhelming proposition.

In any case, the skunkhead flycatchers are a notable and fascinating bit of neotropic avifauna that the birder in Central and South America is unlikely to miss.

  1. February 23, 2010 7:55 am

    Interesting speculations! It is something that has always been a head-scratcher to me. During my stay in Venezuela I had six species of skunkheads to tease apart. It is important to consider in your evolutionary speculations though their common ancestry: despite falling into many different genera, they are actually closely related. According to recent work (Tello et al 2009, let me know if you want that paper) they have their own tribe in Tyrannidae (Tyrannini!) including all of the “skunkhead” patterned birds (Pitangus, Philohydor, Myiodynastes, Myiozetetes, Megarhynchus) plus a few other closely related (and sometimes similarly patterned) groups: Machetornis, Tyrannopsis, the Kingbirds in Tyrannus, Griseotyrannus, and Empidonomus. Actually, it kind of looks like the skunkhead pattern is the ancestral condition to this group, and species like those in Tyrannus are derived to be plain again, but I’d wait to see a more species-level analysis before making those kind of judgements for sure.

  2. Nate permalink*
    February 23, 2010 8:20 am

    @Nick- Speculations are all they are. The paper sounds interesting, and while I was looking for explanations for the similarity, I must have missed it.

    But even if it is a ancestral condition it still breaches the questions, though, as to what selected for the pattern in the first place.

  3. February 23, 2010 8:28 am

    Oh yeah?
    Find skunkheads interesting?


    Well, then just compare this pipit-related bird from Kenya

    to this bird from North America:

    And that sure ain’t a case of common ancestral trait…
    Any explanations?

  4. Nate permalink*
    February 23, 2010 9:10 am

    @Jochen- That’s a pretty classic case of co-evolution, is it not? The birds share a common habitat that selects for a cryptic back and a bright front. Though why two unrelated birds would share the specific pattern down to the black marks on the breast is beyond me. There must be something about it that makes the bird stand out from a great distance on a uniform prairie setting.

  5. February 23, 2010 9:41 am

    I concur with you that it is co-evolution but I really find it remarkable that the patterns are identical to such an amazing extend, actually down to the subtle brown markings and streaks at the sides of the breast.
    There’s got to be more (not meant as a creationist comment!!). Look at the co-evolution of fish and sea mammals: sure there are similarities, but it is still obvious which is which. In the case of longclaw versus meadowlark, I am sure if you showed one species to the birders of the other continents, they’d mostly misidentify it.

    I think this is one of the bird world’s biggest riddles.

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