Breeding seasonality and population dynamics of three rodent species in the Magamba Forest Reserve, Western Usambara Mountains, north-east Tanzania
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Date
2006
Journal Title
Journal ISSN
Volume Title
Publisher
Blackwell Publishing Ltd
Abstract
We investigated breeding seasonality and population
dynamics of three rodent species, Lophuromys flavopuncatus,
Grammomys dolichurus and Praomys delectorum, in the
Magamba Forest, Western Usambara Mountains, northeast
Tanzania. Capture–mark–recapture studies were conducted
in 2002–2004. Reproductive conditions of males
and females showed temporal variations, an indication of
breeding seasonality. Animals were reproductively active
between February and May. Rainfall in November–January
was instrumental for the onset of breeding and continued
throughout the wet season. The recruitment of new individuals
born during the season led to highest population
densities between end of May and August. Populations
declined progressively towards the end of the dry season
(September–October). Only P. delectorum showed a marked
density increase during January–February, indicating
greater survival and/or recruitment during the November–
January rains. The study shows that despite a relatively
stable environment of the forest reserve, rainfall has strong
influence on reproduction and population dynamics,
probably because of its effect on primary food resources.
Key words: breeding, dynamics, Grammomys, Lophuromys,
Praomys, Tanzania
Re´sume´
Nous avons e´tudie´ la chronologie saisonnie`re de la reproduction
et la dynamique de la population de trois espe`ces de
rongeurs, Lophuromys flavopunctatus, Grammomys dolichurus
et Praomys delectorum, dans la foreˆt de Magamba, dans
la partie ouest des monts Usambara, au nord-est de la
Tanzanie. Des e´tudes par capture – marquage – re-capture
ont e´te´ re´alise´es en 2002 – 2004. La condition reproductrice
des maˆles et des femelles pre´sentait des variations
saisonnie`res, un indice de saisonnalite´ de la reproduction.
Les animaux e´taient en e´tat de reproduction active entre
fe´vrier et mai. Les chutes de pluie de novembre a` janvier
e´taient tre`s importantes pour le de´clenchement de la
reproduction et continuaient pendant toute la saison des
pluies. Le recrutement de nouveaux individus ne´s durant
cette saison conduisait a` une densite´ de population qui
culminait entre fin mai et aouˆ t. Les populations de´clinaient
progressivement jusque vers la fin de la saison se`che (septembre
– octobre). Seul P. delectorum montrait un taux de
recrutement et/ou de survie plus e´leve´ pendant les pluies de
novembre a` janvier. Cette e´tude montre que malgre´ l’environnement
relativement stable de la re´serve forestie`re, les
chutes de pluie ont une forte influence sur la reproduction
et la dynamique des populations, probablement a` cause de
leur effet sur les ressources primaires en nourriture.
Description
Keywords
Tanzania, Breeding seasonality, Polulation dynamics, Lophuromys flavopuncatus, Grammomys dolichurus, Praomys delectorum, Magamba Forest, Western Usambara Mountains