-- Katherine Mertes, PhD Candidate
Guest blog post from the Jetz Lab at Yale
Understanding how animals respond to different environmental conditions is an important step in learning why a species occurs where it does. Preference for certain conditions, and aversion toward others, can explain a species’ global range – and, on a more local scale, why a species might be found only in a few specific places within its range. In order to explore such environmental preferences and distribution dynamics for East African birds, we are attaching GPS tags to multiple species. Most recently, we captured and tagged a kori bustard, one of the largest flying birds in Africa.
Capturing a kori begins with conducting surveys across Mpala to identify areas where the species can consistently be found – and where Safaricom signal is strong enough to support the GSM capabilities of the sophisticated tags obtained through collaborators at the University of Konstanz, Germany. After establishing suitable areas, the capture process works like this: spot a kori during the relatively cooler morning and evening periods, as the species is particularly sensitive to heat stress. Determine the direction the kori is headed, then rush of it ahead to hang a monofilament net 3 meters tall and 50 meters long from natural vegetation, oriented perpendicular to the sun (to reduce visibility), while keeping one pair of eyes on the bird to detect any sudden changes in direction. Once the net is securely – and, hopefully, invisibly – strung from acacias, circle back and use the vehicle to carefully, steadily, slowly herd the bird into the net. If all goes smoothly, the kori unwittingly walks into the net, becoming entangled just long enough for us to emerge from the vehicle, secure the bird in a loose yet firm grip, and place a dark hood over its head to induce calm during handling.
In mid-October all did go smoothly for our field team, and we successfully attached a GSM/GPS tag to an adult male kori bustard. Over the next year, precise GPS locations collected every 5-20 minutes will enable us to learn which environmental conditions these birds prefers, and just how far they will travel to track these preferred conditions. When analyzed with movement data from other tagged species at Mpala – such as red-billed and Von der Decken’s hornbills – we hope to be several steps closer to solving fundamental questions of species distribution dynamics.