Abstract:
Arid-zone birds trade-off dehydration and hyperthermia during hot weather, as they are dependent on evaporative cooling when air temperature approaches or exceeds body temperature. Water points in many arid ecosystems become surrounded by piospheres, exposing drinking birds to high radiant heat loads and exacerbating this trade-off. This challenge will be aggravated under climate warming. One possible mitigation approach is to reduce heat loads birds experience when seeking water. We experimentally shaded water points on farmland in the Kalahari. We used a Before–After Control–Impact design to assess the impact of artificial shade on species, visitation rates and visitation patterns of drinking birds. The number of species drinking was not affected by the introduction of shade, but overall visitation rates declined, despite a habituation period prior to data collection and increased use of shaded water points during the heat of the day. Of the ten most common species, one –the smallest species in the study - significantly increased and four significantly reduced visitation rates to experimentally shaded water points. Providing shade benefited few species overall, perhaps because of increased perceived predation risk. Future work should investigate the impacts of shader design in order to develop this method as a conservation tool.
