THE USE OF COUNTS OF NAMAQUA SANDGROUSE AT WATERING SITES FOR POPULATION ESTIMATES

The variety of methods used to count Namaqua sandgrouse Pterocles nama qua at watering sites, and the apparent lack of consensus concerning t he frequency with which they drink, minimizes the usefulness of such c ounts as population estimates. There were significant differences betw een counts of overflying Namaqua sandgrouse, and those that landed and drank at a watering site. Counts on the day preceding the hunt and co unts during hunts were also significantly different. Furthermore, sand grouse which do not drink, take part in group socializing or have a du st bath at the watering site. Individually marked sandgrouse drank as frequently as on four consecutive days. Birds landing, or apparently i ntending to land should be counted, both during hunting and when hunti ng is not in progress. Because some sandgrouse which are disturbed by hunters attempt to return to the same watering site during a hunt, cou nts conducted at hunts should be multiplied by a factor slightly less than 1,0 (i.e. 0,74) to obtain more reliable population estimates. Ave rage total counts of birds landing, or apparently intending to land, m ay be used for population estimates by relating the count to the land area serviced by the watering site.