Open AccessInforming Aerial Total Counts with Demographic Models: Population Growth of Serengeti Elephants Not Explained Purely by Demography
Author(s) -
Morrison Thomas A.,
Estes Anna B.,
Mduma Simon A.R.,
Maliti Honori T.,
Frederick Howard,
Kija Hamza,
Mwita Machoke,
Sinclair A.R.E.,
Kohi Edward M.
Publication year - 2017
Publication title -
conservation letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.153
H-Index - 79
ISSN - 1755-263X
DOI - 10.1111/conl.12413
Subject(s) - tanzania , population growth , population , abundance (ecology) , geography , immigration , demography , population size , african elephant , ecology , biology , sociology , archaeology , environmental planning
Conservation management is strongly shaped by the interpretation of population trends. In the Serengeti ecosystem, Tanzania, aerial total counts indicate a striking increase in elephant abundance compared to all previous censuses. We developed a simple age‐structured population model to guide interpretation of this reported increase, focusing on three possible causes: (1) in situ population growth, (2) immigration from Kenya, and (3) differences in counting methodologies over time. No single cause, nor the combination of two causes, adequately explained the observed population growth. Under the assumptions of maximum in situ growth and detection bias of 12.7% in previous censuses, conservative estimates of immigration from Kenya were between 250 and 1,450 individuals. Our results highlight the value of considering demography when drawing conclusions about the causes of population trends. The issues we illustrate apply to other species that have undergone dramatic changes in abundance, as well as many elephant populations.