Woodcreepers- a diverse group of cryptic, brown, tree-dwelling denizens of Neotropical forest can easily get branded as dull or unspectacular by many visiting birders when compared to the plumage or lifestyle of some other Neotropical specialities.
I think they deserve a bit more focus however, and perhaps are a little more intriguing than first meets the eye…
Traditionally treated as a separate family, Dendrocolaptidae, they now make up part of the vast suboscine Neotropical family of Furnariidae, or vernacularly, the Ovenbirds (confusingly, the Ovenbird itself is actually a New World warbler). As a product of convergent evolution, they display obvious similarities to the (primarily) Old World family of Treecreepers, Certhiidae. As well as being taxonomically unique to the Neotropics, they also lack an obvious counterpart in Asian and Afro-tropical forest, making them a fascinating subject for the study of niche overlap and feeding ecology in relation to age and structure of the forest.
Despite being generally brown and streaked, woodcreepers are highly variable in morphology and size, from some of the smaller and delicate species such as Wedge-billed Woodcreeper, to the brutish Great Rufous and Strong-billed Woodcreepers, the largest and most bullish representatives of Xiphocolaptes.
Although they are primarily known to feed on arboreal arthropods, small vertebrate prey in the shape of lizards, frogs and small snakes have been recorded regularly in some larger species, as well as nest predation and specialist feeding at ant swarms.
There are some 50+ species that make up the woodcreeper guild through Central and South America. They, like most diverse neotropical families, are present in an array of habitat, from the high altitude Polylepis forests of the Andean west slope to lowland rainforest of the Amazon basin. Predictably, South America has the greatest diversity of Woodcreeper species.
Woodcreepers, overall, are rather poorly known. Many basic biological descriptions such as breeding/nesting biology, feeding ecology and moult are lacking in many species and the bioacoustic dynamics in woodcreepers as a whole are very poorly understood. Similarly, taxonomy of woodcreepers is in its relative infancy, with some species likely to actually be represented by a number of species.
For example- the tiny Olivaceous Woodcreeper, currently considered monotypic and thus the only species in its genus Sittasomus is represented by some 20 subspecies (as per IOC taxonomy) from northern Mexico to north-eastern Argentina. It is expected, however, that there are a number of distinct forms within the species, based on morphological and vocal differences. These subspecies have been ‘grouped’ into five radiations, with further study, particularly on vocal analysis, a research priority.
During fieldwork in Honduras (Cusuco National Park) in the summer, I had the chance to get up close and personal with what firmly became one of my favourite avian groups since my first visit to the Neotropics.
Eight species are photographed below that give an insight into the diversity and morphology of this fascinating species group.
Ruddy Woodcreeper Dendrocincla homochroa
Ruddy Woodcreepers are usually associated with Ants and can be tough to see away from swarms. It is restricted to Central America apart from one or two disjunct populations in northern South America.
This is presumably the nominate form homochroa.
Olivaceous Woodcreepers have a huge range throughout the Neotropics. As mentioned earlier, vocally they are very interesting and this range can be explored on the excellent ‘new look’ xeno-canto here.
This is from the form sylvioides which makes up part of the predominantly Central American griseus group (of the five mentioned earlier). One of the characterising features of this group is the whitish or buff wing-band, as can be seen above.
Strong-billed Woodcreeper Xiphocolaptes promeropirhynchus
The powerful Strong-billed Woodcreeper is one of the largest woodcreepers with a range through much of the Neotropics. It, like Olivaceous Woodcreeper, has a poorly understood taxonomy with 24 recognised sub-species (as per IOC). It has been suggested that there are likely to be three distinct radiations under Strong-billed Woodcreeper. This individual is of the form emigrans and part of the Mesoamerican group.
They are impressive beasts in the field, as this video of one devouring a Sphingidae moth shows!
Wedge-billed Woodcreeper Glyphorynchus spirurus
Wedge-billed Woodcreepers have a widespread distribution across the Neotropics and are represented by 14 sub-species. This juvenile is of the the Central American race pectoralis.
Acoustic variation can be considerable, as can be explored here.
Northern Barred Woodcreeper Dendrocolaptes sanctithomae
Formerly subsumed under Amazonian Barred Woodcreeper D.certhia, Northern Barred Woodcreepers have a primarily Central American distribution with Honduran birds representing the nominate form sanctithomae. They are another species known to follow ant swarms.
Northern Barred Woodcreepers have peculiar, but very distinctive vocalisations, as can be heard here.
Spotted Woodcreeper Xiphorhynchus erythropygius
Primarily Central American, Spotted Woodcreeper is a typical montane forest resident, its descending trills are a common sound at dawn around the forests of Cusuco. Honduran birds are represented by ssp. parvus.
Spot-crowned Woodcreeper Lepidocolaptes affinis
Another typical Central American cloud-forest specialist, Spot-crowned Woodcreepers are the most frequently encountered woodcreeper in Cusuco NP and in Honduras are represented by the nominate race affinis. At lower altitudes it is replaced by the congeneric Streak-headed Woodcreeper L.souleyetii.
Tawny-winged Woodcreeper Dendrocincla anabatina
Tawny-winged Woodcreeper remains as something of an enigma in Cusuco, with the first documented records for the park coming during fieldwork in Summer 2012. Although work has taken place here for several years, this is not so surprising given how low detection rates of some woodcreeper species are in thick forest habitat. It is a congener of Ruddy Woodcreeper in Dendrocincla and is also known to feed at ant swarms and even follow troops of Squirrel Monkeys, feeding on fleeing insects. Honduran birds are again represented by the nominate race, anabatina.
Are you birding in the Neotropics soon or have been recently? Seen anything that might shed a bit more light on the cryptic life of a Woodcreeper sp.?
With paucities in basic knowledge such as breeding biology, casual field data can be of significance for a number of species.
If you might have overlooked Woodcreepers a bit in the past, I encourage you to look a little deeper, you never know what you might find out!
Some assorted further reading;
Brooke, M. D. L. (1983). Ecological segregation of woodcreepers (Dendrocolaptidae) in the state of Rio de Janeiro, Brasil. Ibis, 125(4), 562-567.
Irestedt, M., Fjeldså, J., Dalén, L., & Ericson, P. (2009). Convergent evolution, habitat shifts and variable diversification rates in the ovenbird-woodcreeper family (Furnariidae). BMC evolutionary biology, 9(1), 268. [open access]
Irestedt, M., Fjeldså, J., & Ericson, P. G. (2006). Evolution of the ovenbird‐woodcreeper assemblage (Aves: Furnariidae)‐major shifts in nest architecture and adaptive radiation. Journal of Avian Biology, 37(3), 260-272. [open access]
Kupriyanov, V. M. S., Daza, J. D., Bauer, A. M., Gaban-Lima, R., Rocha-Brito, G. R., & Höfling, E. (2012). Six species of Amazonian Woodcreepers (Aves: Dendrocolaptidae) preying upon lizards and frogs. Journal of Natural History,46(47-48), 2985-2997.
Patten, Michael A. (2011). Olivaceous Woodcreeper (Sittasomus griseicapillus), Neotropical Birds Online (T. S. Schulenberg, Editor). Ithaca: Cornell Lab of Ornithology; retrieved from Neotropical Birds Online: http://neotropical.birds.cornell.edu/portal/species/overview?p_p_spp=359106