Adaptive Modification of Tail Structure in Relation to Body Mass and Buckling in Woodcreepers

Abstract

We assessed the relationship between function and tail structure of woodcreepers (Dendrocolaptidae) and Neotropical ovenbirds (Furnariidae) using a comparative analysis of independent contrasts. Because woodcreepers are scansorial (they use their tail for body support), we predicted that the structure of the rectrix rachis should be reinforced both at the tip and at the base, whereas the nonscansorial Neotropical ovenbirds should lack reinforcement of the rectrix tips. For each species, we measured the length of the rachis of the medial rectrix and its diameter both at the tip and base of the feather. Rachis diameters were positively associated with body mass in both groups as expected if tail structure were a simple allometric product of body size. However, woodcreepers had larger rachis diameters for a given body mass and higher slopes in the allometric regressions than Neotropical ovenbirds. In addition, we found positive relationships between rachis width at both the tip and base of the rectrix and tail length in woodcreepers, but in Neotropical ovenbirds only rachis width at the base was associated with tail length. These results considered together are consistent with the hypothesis that the tip of the woodcreeper tail rachis is adapted to both support body mass and to prevent Euler buckling failure. Modificaciones Adaptativas de la Estructura de la Cola en Relación a la Masa Corporal y al Pandeo en Pájaros Trepadores Resumen. Se evaluó la relación entre la función y la estructura de la cola en los trepadores (Dendrocolaptidae) y los furnáridos (Furnariidae) usando un análisis comparativo de contrastes independientes. Debido a que los trepadores son escansoriales (es decir que usan su cola para el soporte del cuerpo), se predijo que la estructura del raquis de la rectriz debería estar reforzada tanto en la punta como en la base mientras que la de los furnáridos que no son escansoriales debería carecer del reforzamiento en la punta. Para cada especie se midió el largo del raquis de la rectriz medial y su diámetro, tanto en la punta como en la base de la pluma. Los diámetros del raquis estuvieron positivamente asociados con la masa corporal en ambos grupos, tal como se esperaría si la cola fuera el simple producto de una relación alométrica con el tamaño corporal. Sin embargo, los diámetros del raquis para una dada masa corporal y las pendientes de las regresiones alométricas fueron mayores en los trepadores que en los furnáridos. Además, se encontraron relaciones postivas entre el ancho del raquis en la punta y en la base de la rectriz y el largo de la cola en trepadores, pero solamente el ancho del raquis en la base estuvo asociado con el largo de la cola en furnáridos. Estos resultados considerados en su conjunto son consistentes con la hipótesis de que la punta del raquis en la cola de los trepadores está adaptada para soportar la masa corporal y prevenir el pandeo de Euler.

Discovering Exceptional Diversifications at Continental Scales: The Case of the Endemic Families of Neotropical Suboscine Passerines

“…Foot morphology is also more heterogeneous in the Furnariidae‐Dendrocolaptidae clade, which shows variation in the relative length of toe IV and claw curvature (Richardson 1942; Feduccia 1973). Finally, in addition to the variation in feather length, the tail in Furnariidae and Dendrocolaptidae shows notable variation in structural details such as rachis thickness, which are adaptations to trunk climbing (Tubaro et al 2002), barb integration, including extreme cases of weak barb development like Sylviorthorhynchus (Remsen 2003), and feather tip morphology, which varies from rounded to extremely pointed (Fjeldså et al 2005). Other families in the suborder Furnariides are more homogeneous in these external morphological details, which perhaps was one of the reasons several of them were considered a single family in the past (Formicariidae).…”

Ecological drivers of song evolution in birds: Disentangling the effects of habitat and morphology

“…In this study, we use phylogenetic comparative techniques to assess the relative roles of direct and indirect ecological selection on song diversification across 285 species of ovenbirds (Furnariidae), a diverse clade with comprehensive data on phylogenetic relationships, morphology, and song (Derryberry et al., ; Tobias et al., ). Ovenbirds are an ideal system because they exhibit high diversity in both habitat preferences and morphological characters associated with feeding (Claramunt, ; Marantz, Aleixo, Bevier, & Patten, ; Raikow, ; Remsen, ; Tubaro, Lijtmaer, Palacios, & Kopuchian, ). Moreover, in common with other tracheophone suboscine passerines (Tobias & Seddon, ; Tobias et al., ; Touchton, Seddon, & Tobias, ), their songs appear to be innate with song learning limited or absent.…”

Correlated Evolution of Beak Morphology and Song in the Neotropical Woodcreeper Radiation

“…obs.). In addition, woodcreepers exhibit extreme diversity in morphological characters associated with feeding and locomotion (Raikow 1994; Tubaro et al 2002; Marantz et al 2003; Claramunt 2010); in particular, their beaks range from small and straight (e.g., Certhiasomus ) to long and down curved (e.g., Campylorhampus “scythebills”) (Fig. 1), suggesting that biomechanical limitations vary across the clade.…”