Anvil use for seed consumption by the White-fronted Woodpecker Melanerpes cactorum during summer season with diverse resource availability

MARÍA GABRIELA NÚÑEZ MONTELLANO; PATRICIA VIVIANA ZELAYA; PEDRO G. BLENDINGER

Journal of Ornithology

German Ornithologists' Society

Año: 2021 vol. 162 p. 669 - 676

2193-7192

The use of anvils for foraging allows access to food that cannot be exploited otherwise by most birds or other animals. This may be especially important in habitats where food resources are scarce or fluctuate seasonally and where animals exploit novel and highly nutritional food resources that require unconventional foraging techniques to acquire energy. In dry woodlands of northern Argentina, the White-fronted Woodpecker, Melanerpes cactorum, secures seeds from a shrub species, Sarcotoxicum salicifolium, by wedging the seeds into crevices, holes, or forks within plant structures, where they peck the hard cover of the seeds to extract the embryo. The aim of this study was to evaluate whether the anvil use by the White-fronted Woodpecker conforms to or differs from the anvil use by other woodpecker species. Specifically, we (1) described the behaviour of seed consumption mediated by using anvils in plant structures, and (2) analysed the use of anvils for seed consumption relative to seasonality and food availability in the dry Chaco of Argentina. The woodpecker matched the size of the seed to the anvil, and seeds were positioned mostly with a specific orientation pattern in structures of seven plant species, facilitating opening and extraction of the complete embryo. As in other anvil-using woodpecker species, this pattern of deliberate manipulation and orientation of seeds by the woodpeckers may imply spatial association of the seed and the site used as an anvil, a behaviour that could be cognitively more demanding than simply using an anvil. In contrast with other anvil-using woodpecker species, seed consumption mediated by anvil use was most important in summer (i.e. breeding season), when S. salicifolium seeds were more abundant but also when the availability of food resources was more diverse and abundant. The seed embryos are likely an important source of nutrients and more profitable than other less protected food resources for the White-fronted Woodpecker, particularly during the breeding season when energy demands increase.