The effect of supplemental food on the growth rates of neonatal, young, and adult cotton rats (Sigmodon hispidus) in northeastern Kansas, USA

Published source details Eifler M.A., Slade N.A. & Doonan T.J. (2003) The effect of supplemental food on the growth rates of neonatal, young, and adult cotton rats (Sigmodon hispidus) in northeastern Kansas, USA. Acta Oecologica, 24, 187-193.
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This study is summarised as evidence for the following.

	Action	Category
	Provide supplementary food to increase reproduction/survival Action Link

Provide supplementary food to increase reproduction/survival

A replicated, controlled study in 1990–1992 in a forest reserve in Kansas, USA (Eifler et al. 2003) found that cotton rats Sigmodon hispidus had different growth rates after the provision of supplementary food, depending on their size and sex, and the time of year. In winter, the growth rate of small cotton rats provided with supplementary food was significantly higher than that of small rats not provided with food, but the opposite was true for larger rats. In spring, males on supplemented grids grew faster than males on control grids, but the opposite was true in females. In summer, there was no difference in growth rates between supplemented and non-supplemented grids. In autumn, males were the same as in winter, but larger females grew faster with supplementary food (data presented as model results). Additionally, seven reproductive cotton rat females had a higher growth rate when provided with food (2.5 g/day) than did 14 non-supplemented females (2.0 g/day). Seven litters born to females on food supplemented grids had higher growth rates in their first month of life (1.4 g/day) than 23 litters born on non-supplemented grids (0.94 g/day). Between June 1990 and May 1992, supplementary food was distributed along two out of four trapping grids. Food (50 g each of sorghum seeds, millet seeds and commercial rabbit chow) was provided in cans that were refilled every two weeks. Grids contained 64–99 trapping stations, 15 m apart, each with two Sherman traps baited with scratch grain. Traps were set for three consecutive days/month, and checked twice daily. Rats were individually marked and weighed when captured. In June 1991, one of the food supplemented and one of the non-supplemented grids were switched.

(Summarised by: Ricardo Rocha)