Naivasha Notes 5
Evan Buechley— 24 August 2010 — in East Africa Project Share
As I last posted, I had noted significant declines in the number of active Augur buzzard territories in three of the four survey areas around Lake Naivasha, Kenya. In the last few weeks of July, I finished surveys within Hell’s Gate National Park (HGNP), to conclude the census. Results indicate that there has been a decline from 36 to 24 active Augur buzzard territories overall since the 1990’s, for a loss of 33 percent. While territory abandonment has tended to be most extreme in areas of highest human disturbance (up to 60%), it is notable that declines have also been significant in control-like sections of the study area, including HGNP and Mundui. Both of these areas have remained largely unchanged over the past 15 years, as they are managed for land and wildlife preservation. Declines in the numbers of active territories in these areas have been documented at 33 percent and 29 percent respectively, roughly reflecting the overall trend. All in all, there have been striking declines in the number of active Augur buzzard territories around Lake Naivasha since the 1990’s. These declines have occurred in both horticultural areas and natural reserves. The question that remains is: Why?
During his extensive study of the species around Lake Naivasha in the 1990’s, Munir Virani recorded several Augur buzzard mortalities. Human persecution, poisoning, drowning in cattle troughs, and electrocution from power-lines were all documented as causes of death (Virani1999). It can be assumed that similar mortalities are ongoing or increasing as habitat continues to be modified for flower-farms and human settlement and as the human population continues to grow at a rapid pace. While looking at the map of abandoned territories, one particularly concentrated clump is noticeable surrounding Kamere, a population center that has grown rapidly over the last decade (Virani, pers. comm.), and that is now home to thousands of residents.
The declines around highly populated areas are not all that surprising. What I find to be of most concern are the losses within protected areas. Why have these territories been abandoned? Is it related to food availability? Is it a result of human disturbance of nesting territories? Or, of even more concern, has there been a collapse in the “floating” Augur buzzard population- those birds available to fill territory vacancies? This, in some ways, is the most plausible answer, as several territories that have been recently active and have suffered no noticeable habitat degradation have been left vacant in recent years. If this is the case, the declines of active Augur buzzard territories around Lake Naivasha may hint at more widespread woes for Africa’s Augur buzzards.
At the moment, I sit on a porch in mountainous northern New Mexico, watching a newly fledged Red-tailed hawk take short flights between ponderosa trees as it begs aggressively for food from it’s tiring parents. This is a life-stage (the fledging of chicks) that I didn’t get to observe while watching Augur buzzards in Kenya’s Rift Valley. When I departed just a few weeks ago, however, several pairs were incubating nests religiously, leaving me hopeful that, given the opportunity, Augur buzzard pairs will someday refill the many territories that have recently been abandoned around Lake Naivasha. I hope that further research is conducted soon to clarify some of the questions regarding why Augur buzzards are declining, so that we may begin work to reverse this trend.
I would like to thank Munir Virani for his extensive assistance and guidance with this study. Secondly, several landowners around Lake Naivasha warmly welcomed me onto their private property, for which I am very grateful. These include Andrew and Sarah Eneskilin of Mundui, Liz Tsakaris, Peter and Teresa Swagger of Oserian Flowers, and the Barton family. Sarah Higgins provided coffee, mice, and great conversation, while Simon Thomsett provided amazing insight and needed diversions. Lastly, Elsamere Conservation Center was home for the summer, and with a staff of incredibly friendly, conservation-minded people, it cannot be recommended higher as a place to stay at Lake Naivasha.
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