Saturday, January 23, 2010


The Island of Cozumel lies a mere 20km off the east coast of the Yucatan Peninsula and is only 45km by 15km in size. There are mangroves around the island's coast but the habitat is mostly "semi-humid" scrub, a fascinating tropical habitat type that does not grow particularly tall despite receiving reasonable quantities of water (rainfall). This habitat type is also found in the eastern Yucatan Peninsula.

The theory of island biogeography would predict that such an island have moderate biodiversity, limited by its small size but augmented by frequent arrivals from the mainland. Cozumel, however, is something of an enigma, since it has four endemic species and many distinctive endemic subspecies, perhaps surprising given its proximity to the mainland. The avifaunal mixture of Cozumel is also intriguing in that, although it shares some species with the mainland, there are a suite of species with a more Caribbean distribution, including for example the Western Spindalis that occurs on Cozumel but not on the mainland. Other bird like Yucatan (Yellow-lored) Parrots and White-crowned Pigeons don't mind making the crossing on a regular basis, apparently even twice daily in some seasons.

The four Cozumel endemic species include a hummingbird, a vireo, a thrasher and a wren. The hummer is the Cozumel Emerald, and what a beauty! Unfortunately, the long, deeply forked tail of the male doesn’t show very well in these photos... but you get the picture!

The Cozumel Vireo is very distinctive. This species spends most of their time skulking in the scrub and is not easy to see well.

I didn’t manage photos of the other two endemics – the skulking Cozumel Wren – basically a House Wren who probably took a liking to island living and decided they didn’t feel like traveling back north... well, at least migration suspension seems like the most plausible explanation (or maybe they discovered Tequila?). The fourth endemic, the Cozumel Thrasher, is now feared extinct. Apparently they were common until the hurricane in September 1988. Since then there have been very few sightings and it seems as though this species will not recover. Many other local breeding species took a hit in that hurricane but they have since recovered. Perhaps there was something unusual about the thrasher or perhaps there was a cocktail of factors with the hurricane being the last straw… we may never know!

Cozumel is also a good place to see some of the Yucatan Peninsula endemics. The Yucatan Vireo is an inch or more larger than the Cozumel Vireo, with a much larger bill and with a global range that is restricted to the eastern portion of the Yucatan Peninsula and islands, being found in the characteristic semi-humid tropical scrub habitat of the region and also in mangroves. As it turns out, Cozumel was the only place I saw Yucatan Vireo. Note how thick the supercilium is on this species.

Another Yucatan endemic that seems easier to see on Cozumel than elsewhere is the Yucatan Woodpecker. In most sites in the Yucatan the much larger Golden-fronted Woodpecker is easier to see than the endemic Yucatan Woodpecker, but on Cozumel the converse was true! Note the yellow nasal tuft on this species, one of the features that separate them from Golden-fronted Woodpecker. According to Howell the yellow should extend underneath the bill but that didn’t really seem to be the case with the Cozumel birds… anyone care to comment?

Yet another Yucatan endemic, the Black Catbird, skulks around in the shrub layer, sometimes coinciding with overwintering Gray Catbirds. Once again, this species was easier to see on Cozumel than most sites on the mainland.

Then there are those Cozumel endemic subspecies. On Cozumel endemic rufivertex subspecies of Yellow Warbler has a rufous crown, although in this photo the crown is not so easy to see. Migrant Yellow Warblers from the north also occur.

The caboti subspecies of Bananaquit is only found only Cozumel and a tiny portion of the northeasternmost corner of the Yucatan Peninsula. Their range is very disjunct from the mexicana subspecies which you can see in Belize, northeastern Guatemala, Chiapas and the southernmost parts of Veracruz and Oaxaca. The caboti subspecies of Bananaquit is larger and has a white throat as opposed to the grey throat of mexicana.

Cozumel’s endemic intermedia subspecies of Yellow-faced Grassquit has less black on the chest than mainland races.

Cozumel is the only place is Mexico to see the stunning Western Spindalis, formerly known as Stripe-headed Tanager. This species occurs on many Caribbean Islands and of course is a highly sought-after rarity in Florida. The first photos shows the vibrant colours of the male – a very cooperative little chap who popped up in front of me at eye level. The second photo shows the female enjoying a feast!

Other Cozumel residents with a Caribbean affiliation include the Caribbean Elaenia, found on offshore islands and the eastern most portion of the Yucatan peninsula. Like many flycatchers in this group this species is not easy to identify from other similar species; however, their bright orange lower mandible is a particularly noticable and recognizable feature.

The Caribbean Dove has a somewhat similar distribution to the Caribbean Elaenia; however, their range extend much further westward and also further south in the Caribbean Island chain. Not easy to tell from White-tipped Dove, but their grey, as opposed to vinaceous, crown is a good feature.

Cozumel also has its share of species with more widespread distributions. One of these is the handsome Mangrove Cuckoo. In my experience, Cozumel is the easiest place there is to see this skulker, which is notoriously difficult to find through much of their range. On Cozumel, this species is not confined to mangroves and I saw them in fruiting trees and also in semi-humid scrub.

The Bright-rumped Attila is a widespread flycatcher, ranging from Mexico to Brazil. This one popped up for me and gave good views for a minute or so. Note the hooked bill shape.

Tropical Mockingbird is also wide ranging, although, unlike most of the species covered in this post, they are easy to see anywhere in their range.

Cozumel also attracts its share of Nearctic breeding migrants, including a good selection of shorebirds like the beautiful Black-bellied Plover (American English) or Grey Plover (British English) or Silver Plover (me!).

Another migrant, a Sora, strolls around on some exposed mud. I don’t often see Sora this well up here on their breeding grounds!

And a Palm Warbler forages in the leaf litter… In a few short months, I will be surveying for this species and other boreal breeders as part of the Manitoba Breeding Bird Atlas… but they are content to stay on Cozumel for now!

Another familiar face – indeed a familiar masked face, Raccoons are resident on Cozumel. Like here in North America they are not shy about feeding on human garbage. On the other hand, there is no need to sleep away the winter months down on Cozumel!

More to come soon… but first, better go shovel that fresh snow!

1 comment:

  1. Hey,thanks for the visit to Cozumel. This was very interesting,and I didn't even have to pack a suitcase.:)Jake and I are eagerly waiting for spring and more birding in Manitoba.Have a great day.


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