Population biology of the harvest mouse (Micromys minutus) inhabiting salt marsh in northern Taiwan

Little is known about the ecology of the harvest mouse (Micromys minutus) in Taiwan, the southeast limit of its distribution range.   We studied a population inhabiting the Guandu salt marsh at suburb Taipei.  We established a 70m X 220m trapping grid, and monitored the harvest mouse population by capture-mark-recapture method and habitat quality (in terms of cover and food availability) monthly.  Three patch types existed within the grid: para grass (Brachiaria mutica) patch, reed (Phragmites communis) patch, and a mixture of both.  Our results showed that the harvest mice probably bred all year round.  The recruitment started to increase in September, peaked in the following March, and slowly declined to near zero in June.    Population sizes fluctuated synchronously with the recruitment rates which indicated the important role of recruitment on this population.  On the other hand, the turnover rate remained high year round.  Demography, particularly recruitment rate, varied greatly among subpopulations inhabiting different habitat patches.  Para grass patches had the highest mouse densities, recruitment rates, and proportion of junveniles in recruitments.  Changes in the proportion of high quality patches through succession or disturbance would affect the population dynamics of harvest mouse in Guandu salt marsh.