Insect-repelling behavior in goitered gazelles: responses to biting fly attack

Abstract

Ungulates suffer greatly from a variety of biting flies, the results of which decrease their feeding and resting time and force them to move to lower-quality habitats and unvegetated areas. This in turn leads to weight loss in adults, lower milk production in mothers, and growth retardation in young. An ungulate’s first line of defense against blood-sucking flies is its insect-repelling behaviors that include head waving, ear flapping, tail flicking, and foot stamping. Ungulates also can respond to a biting fly attack by gathering into larger groups to lessen the number of flies per individual (dilution effect) and by finding microhabitats with lower temperatures and stronger winds, where fewer biting flies are found. In this paper, I considered the insect-repelling behaviors of goitered gazelles to better understand the protection strategies of wild ungulates against fly attacks to enhance the management of domestic animals. I found that (a) goitered gazelles demonstrated the highest rate of insect-repelling behavior during the hot and windless summer months, which was the most favorable time of year for biting fly activity; (b) smaller body-sized fawns and sub-adults performed fly defensive behaviors significantly less often than adults, while there were no differences in repelling behavior rates between adult males and females in spite of the discrepancy in their body sizes; (c) goitered gazelles increased their group sizes through the summer months of high biting fly activity; and (d) during summer, the gazelles used landscape features to find elevated and unvegetated sites with lower temperatures and higher wind speeds to lower fly activity. Blood-sucking fly activity is very likely a powerful environmental factor under which ungulate hosts significantly modify their behaviors in order to escape the pain and harassment—and lessen the costs—from biting fly attacks.