Effects of helpers on juvenile development and survival in meerkats

Although breeding success is known to increase with group size in several c ooperative mammals, the mechanisms underlying these relationships are uncer tain. We show that in wild groups of cooperative meerkats, Suricata suricat ta, reductions in the ratio of helpers to pups depress the daily weight gai n and growth of pups and the daily weight gain of helpers. Increases in the daily weight gain of pups are associated with heavier weights at independe nce and at 1 year of age, as well as with improved foraging success as juve niles and higher survival rates through the first year of life. These resul ts suggest that the effects of helpers on the fitness of pups extend beyond weaning and that helpers may gain direct as well as indirect benefits by f eeding pups.