DOI: 10.5061/dryad.p8cz8w9x5
title: Lesser Woodcreepers (Xiphorhynchus fuscus) excavate nest cavities in trees

description: To understand the evolution, life-history trade-offs, and population
 ecology of cavity nesters, it is critical to identify the avian lineages
 and circumstances in which birds excavate tree cavities. Woodcreepers
 (Furnariidae: Dendrocolaptinae; 56 species) are considered non-excavators
 dependent on existing cavities. We overturn this assumption by providing
 definitive evidence that the Lesser Woodcreeper (Xiphorhynchus fuscus, 23
 g) is a facultative tree-cavity excavator. From 2007 to 2022 in the
 Atlantic forest of Misiones, Argentina, they nested in pre-existing tree
 crevices (4 nests), or excavated in trunks of large-diameter trees or
 stumps in advanced stages of decay (mean: 58 cm diameter; range: 22–121
 cm; 22 nests). Nest entrances were vertically elongated and chambers were
 usually pocket-like, excavated in the exterior of the trees (sapwood),
 with floors that curved along the trees' circumference. Excavating
 woodcreepers pulled out elongated, fibrous pieces of decayed wood with a
 spongy texture, tapping only when inside cavities. Published and online
 photographs of nests of Xiphorhynchus species suggest that excavation may
 be widespread in the genus. Our observations that woodcreepers tore out
 elongated pieces of spongy wood (rather than hammering) are consistent
 with the idea that their long, thin bills are more resistant to torsion
 and less resistant to impact compared to the stouter bills of other
 excavators in Passeriformes and Piciformes. Research has tended to focus
 on birds with chisel-shaped bills, perforating harder sapwood to create
 nesting chambers in the center of heartrot-infected trees (resulting in
 typical woodpecker cavities, with circular floors). We hypothesize that
 Lesser Woodcreepers have adopted an alternative strategy, selecting large
 trunks with soft outer wood (sapwood), stopping their excavation radially
 if they reach harder wood, and then expanding the nest chamber laterally.
 Furnariidae may offer a useful model family for understanding ecological
 and evolutionary factors that influence cavity excavation.
description: We studied Lesser Woodcreeper
 at Cruce Caballero Provincial Park (San Pedro department, Misiones,
 Argentina; 26°31'S 54°00'W; 550–600 m asl). Carlos Ferreyra and
 Milka Gomez found trees with woodcreeper excavation activity. They made
 videos of excavating woodcreepers using a camera in hand, camera mounted
 on tripod, or iPhone (original) coupled to a Celestron telescope. Videos
 were trimmed for length.
description: # Nest cavity excavation by Lesser Woodcreeper Xiphorhynchus fuscus (Aves:
 Furnariidae: Dendrocolaptinae)
 [https://doi.org/10.5061/dryad.p8cz8w9x5](https://doi.org/10.5061/dryad.p8cz8w9x5) The dataset contains four videos of Lesser Woodcreepers (Xiphorhynchus fuscus) excavating nest cavities in trees at Parque Provincial Cruce Caballero, San Pedro, Misiones, Argentina. All videos were made by Carlos Ferreyra and/or Milka Gomez. ## Description of the data and file structure The file names correspond to Trees 1, 2 and 3 identified in the corresponding journal article. ## Sharing/Access information N/A