Abstract
ABSTRACTFeather holes are small (0.5–1 mm in diameter) deformities that appear on the vanes of flight feathers. Such deformities were found in many bird species, including galliforms and passerines. Holey flight feathers may be more permeable to air, which could have a negative effect on their ability to generate aerodynamic forces. However, to date the effects of feather holes on flight performance in birds remained unclear. In this study we investigated the relationship between the number of feather holes occurring in the wing or tail feathers and short term flight performance traits – aerial manoeuvrability, maximum velocity and maximum acceleration – in barns swallows, which are long distance migrating aerial foragers. We measured short-term flight performance of barn swallows in a standardized manner in flight tunnels. We found that acceleration and velocity were significantly negatively associated with the number of holes in the wing flight feathers, but not with those in the tail feathers. In the case of acceleration the negative relationship was sex specific – while acceleration significantly decreased with the number of feather holes in females, there was no such significant association in males. Manoeuvrability was not significantly associated with the number of feather holes. These results are consistent with the hypothesis that feather holes are costly in terms of impaired flight. We discuss alternative scenarios that could explain the observed relationships. We also suggest directions for future studies that could investigate the exact mechanism behind the negative association between the number of feather holes and flight characteristics.
Highlights
Feathers are integument structures that have evolved in theropod dinosaurs and nowadays are representative of birds
In general linear model with maximum acceleration as dependent variable, this flight trait was significantly negatively associated with the number of holes present in the wing flight feathers, and this relationship was more pronounced in females than in males (significant interaction wing feather holes × sex; Table 1, Figure 2(a))
In the present study of barn swallows we found that two short-term flight performance traits – maximum acceleration and maximum velocity – were significantly negatively associated with the number of holes present in the wing flight feathers
Summary
Feathers are integument structures that have evolved in theropod dinosaurs and nowadays are representative of birds. The quality of bird feathers is important for such functions of the plumage as flight performance, mechanical protection, thermal insulation, water repellence, and visual communication (Jenni and Winkler 1994). These feather deformities are found in many different bird species, including rock ptarmigan Lagopus muta (Stenkewitz et al 2017), barn swallow Hirundo rustica (Møller 1991), and other passerines (Vas et al 2008; Vágási 2014). It was thought that feather holes are the traces of the grazing activity of chewing lice (Phthiraptera: Amblycera, Ischnocera; Møller 1991; Vas et al 2008; Møller et al 2004a, 2004b; Stenkewitz et al 2017). Recently it has been suggested that chewing lice may not be the main causative agent of feather holes and other factors, such as keratinolytic microorganisms and developmental defects in the structure of feathers, can be involved (Vágási 2014)
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
