Display site selection in a ground dwelling bird: the importance of viewshed

We studied the effects of visibility, female and male distribution, microhabitat and distance to human infrastructure on display site selection in a ground-dwelling bird, the Canarian houbara bustard. Using a very high-resolution digital elevation model based on LIDAR technology, and a complete census of the breeding population, we compared 98 display sites with randomly generated sites through generalized linear models. Univariate analyses showed that males displayed at locations that increased their visibility, both at short and long distances. Interestingly, although numbers of females and males around sites did not differ between display and random locations, from display locations males could see more females and males at both distance ranges. The absence of vegetation and stones was also critical as it allowed males to perform display runs on a ground free of obstacles. The amount of trophic resources did not correlate with the selection of the display site itself, though an appropriate vegetation cover seemed to be important at a wider habitat scale. Finally, display sites were farther away than random sites from sources of human disturbance, such as urban nuclei, buildings and tracks. Logistic regression analyses confirmed the importance of viewshed, low stone and vegetation cover, and distance to urban centres and tracks, and model averaging identified short-range visibility and females visible in the long range as the most important visibility variables. These results are compatible with the sexual advertisement and predator avoidance hypotheses. We provide recommendations to ensure an appropriate management of the breeding habitat of this endangered subspecies. For a male, choosing a suitable display site is critical to effectively transmit his sexual signals, and to do so safe from predators. This is particularly important in terrestrial birds, which have to allow for topographical irregularities and the risks of living on the ground. We show how houbara bustard males display from sites that offer the best viewsheds, and more importantly, maximize the number of visible females, increasing their chances of attracting potential mates.

Automated summary

We investigated the factors influencing display site selection in the Canarian houbara bustard, including visibility, female and male distribution, microhabitat, and distance to human infrastructure. Our findings suggest that the bustards prefer display sites with higher visibility, devoid of vegetation and stones, and located farther away from human disturbance sources. Male bustards are particularly attracted to sites with better viewsheds and a higher number of visible females at both short and long distances.