Sex and age differences in the preference for materials for the communal nests of sociable weavers Philetairus socius

Abstract

Many animals build structures that are used for shelter, reproduction or to capture prey. The type of material used to build these structures is likely to influence their solidity, thermoregulation capacity and, in some species, may influence the attractiveness of the builders. In the case of animal nests, evidence for preference of nesting material has been documented in several species but, to date, few field experiments have been conducted, and it was seldom investigated whether individuals' attributes affected those preferences. We investigated these preferences in relation to individual attributes on sociable weavers (Philetairus socius) that build communally one of the largest known nest structures, using dry grass. We conducted an experiment where we presented two piles of straws, long and short, to wild individuals. We recorded 900 h of video and used a deep learning method to automatically detect images where birds were present (266 colour‐ringed individuals). Our results showed that males picked more straws than females and showed a preference for longer straws, while no preference was found for females. In addition, older males showed a preference for long straws compared to younger males. Finally, males displayed higher repeatability than females in their preference for longer straws. In conclusion, we show that choice of nesting material is not random, and that preferences are associated with individual attributes. Future studies should assess how building is associated with social status, mating and reproductive success of the individuals building, to investigate which of these factors could have shaped the evolution of these preferences.

Repeatability of an extended phenotype: potential causes and consequences of nest variation in the Northern House Wren (Troglodytes aedon aedon)

“…When among-individual variation is high and within-individual variation is low, then the repeatability estimate will be high and that trait will be considered repeatable. Repeatability estimation can be used to understand the extent to which phenotypic traits are the product of static characteristics, such as heritability (“upper level of heritability”; Bell et al 2009, Møller 2006) and individual preferences (Mennerat et al 2009, Järvinen & Brommer 2020, Silva et al 2024), or plastic characteristics, such as experience (DiRienzo et al 2019, Whittaker et al 2023). For this reason, the repeatability of a large variety of behaviors have been examined across taxa (Bell et al 2009), but there are few studies examining the repeatability of construction behaviors.…”

“…For this reason, the repeatability of a large variety of behaviors have been examined across taxa (Bell et al 2009), but there are few studies examining the repeatability of construction behaviors. Most of these studies have focused on spider web structure (Fisher et al 2019, DiRienzo et al 2020, DiRienzo & Montiglio 2016) or nest morphology (Rushbrook et al 2008, Muth & Healy 2011, Whittaker et al 2023), but few have examined the behavior exclusively in the wild (Møller 2006, Järvinen et al 2017, Silva et al 2024).…”