The chicks of an Amazonian bird called the Cinereous mourner (Laniocera hypopyrra) mimic toxic, hairy caterpillars of the flannel moths both in appearance and behavior, says a team of ornithologists led by Dr Gustavo Londono from the University of California, Riverside.
Top: Laniocera hypopyrra nestling in lowland Amazonian forest in southeastern Peru. Image credit: Santiago David. Bottom: caterpillar (family Megalopygidae) in the area that matches the nestling’s plumage characteristics. Image credit: Wendy Valencia.
Discovered by French scientists Louis Jean Pierre Vieillot in 1817, the Cinereous mourner is a species of passerine bird in the family Tityridae.
The bird is widely distributed over the greater part of Amazonia with a geographically separate population in the central Atlantic Forest.
It has dark eyes with narrow orange eyering, dark bill, grey legs, rounded head and bill yielding appearance somewhat like that of a dove.
Adults are typically between 20 and 21 cm long, with a weight of 41-51 g.
The bird is a generally uncommon and rather inconspicuous forest-dweller. It inhabits relatively tall-canopy terra firme forest, but is also found in seasonally flooded swampy forests as well as in humid sandy-belt woodland, more extensive savanna forests and on wooded sand-ridges.
During the fall of 2012, while working on a long-term avian ecological study, Dr Londono and his colleagues discovered an extremely rare nest of the Cinereous mourner at Pantiacolla Lodge in the upper Madre de Dios River in southeastern Peru.
They observed that upon hatching, the nestlings had downy feathers with long orange barbs with white tips, which was very different from any other nestling they had observed in the area. The peculiar downy feathers attracted their attention, but the nestling behavior provided a more important cue.
While the ornithologists were collecting morphological measurements, the nestling started moving its head very slowly from side to side in a way typical of many hairy caterpillars.
While working in the area, they found poisonous caterpillars of the flannel moths (family Megalopygidae) with similar size and hair coloration as the nestling.
In a paper published in the journal American Naturalist, they suggest that this is an example of Batesian mimicry in which the nestling tricks predators into thinking that it is a toxic, spiny caterpillar rather than a highly edible nestling.
“While there is little evidence of Batesian mimicry in birds, there are examples of warning coloration,” the scientists wrote in the paper.
“For example, the hooded pitohui (Pitohui dichrous) has aposematic plumage (black and orange) and contains toxins. It is possible that Laniocera hypopyrra nestlings contain toxins, in which case their characteristics would be best described as Müllerian mimicry. However, we think this is unlikely.”
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Gustavo A. Londono et al. 2015. Morphological and Behavioral Evidence of Batesian Mimicry in Nestlings of a Lowland Amazonian Bird. American Naturalist, vol. 185, no. 1, pp. 135-141; doi: 10.1086/679106
