It is from this study that we arrived at the estimate of up to 600 birds dying per day. These deaths are not spread across the lake, and at least half the lake does not have high numbers of birds dying. There are estimated to be one million flamingos at the lake. Dr Harper observed that the birds displayed a common behavioural pattern before death - their heads drooped and the birds moved towards the shoreline to prevent drowning. They lost muscle control and eventually fell over.
Stress can lead to flamingos being more susceptible to other causes of death.
There is a prolonged drought bringing about a shortage of fresh water on which the birds depend. It is very possible that this lack of fresh water is the stress catalyst responsible for these deaths. Dr Harper added the flamingos at Lake Bogoria had become a fairly resident population because of other changes in the patterns of lake level in rift valley lakes over the past few years, but even so the numbers of deaths were higher than natural mortality. The fact that the birds were crowded and less mobile could mean that they were more susceptible to bacterial infection. Dr Harper said that theories about the effect of pollution were also being tested and the Leicester team has left equipment for the Kenyans in charge of the Lake Bogoria National Reserve to use in their investigations.