A model to search for birth probabilities of mammal populations using fertility data.
A model was constructed to predict monthly birth probabilities using mammalian fertility data. We used a sample of 147 female capybaras (Hydrochoerus hydrochaeris) hunted on a farm on Marajó Island, Brazil. In the model each month was treated as a multinomial with six cells representing the six possible reproductive states (five months gestation). A hypothesis test was carried out to see whether a cosine curve would fit the birth probabilities. The results offer no support for a seasonal component (F2,9 = 1.84, P = 0.21), whereas results from a direct census do (F3,23 = 87.29, P < 0.01). Some hunting techniques were biased towards killing pregnant females (chi(2)1= 7.2, P< 0.01), thereby spreading reproduction throughout the year (F2,9 = 1.84, P = 0.21). The model remained a powerful predictive tool to be used with mammalian fertility data as long as the data are not biased towards pregnant females.
Moreira
J R
JR
Embrapa Recursos Genéticos e Biotecnologia, Brasília, DF, Brazil. jmoreira@cenargen.embrapa.br
Eagle
M
M
Gillespie
O J
OJ
Davidson
A
A
Marriott
F H C
FH
Macdonald
D W
DW
D000818:Animals; D001723:Birth Rate; D005260:Female; D005298:Fertility / Q000502:physiology*; D008954:Models, Biological; D011157:Population Dynamics; D011247:Pregnancy; D012377:Rodentia / Q000502:physiology*