Breeding seasonality and population dynamics of three rodent species in the Magamba Forest Reserve, Western Usambara Mountains, north-east Tanzania

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Blackwell Publishing Ltd


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.



Tanzania, Breeding seasonality, Polulation dynamics, Lophuromys flavopuncatus, Grammomys dolichurus, Praomys delectorum, Magamba Forest, Western Usambara Mountains