MATERNAL CARE AS A LIMITED RESOURCE
It seems obvious that parental antipredator behavior should benefit all offspring simultaneously. However, if the parents are unable to successfully defend all of their offspring all of the time, the risk of predation becomes unequally distributed. For example, broods that are relatively large often display a selfish herd effect, where the individuals closest to the outside edges of the aggregation are at a greater risk of predation than the individuals located near the middle. It seems reasonable for siblings to compete for the most protected or defensible locations, which also contributes to the unequal distribution of risk. The parent's ability to defend all offspring at once is also largely dependent on the spatial configuration of the brood: the farther an individual is from the parent, the greater their risk of predation. In the U. crassicornis, maternal protection is also influenced by signals produced by the offspring. The signaling, which consists of synchronous vibrational bursts, appears to be coordinated. This coordination would be expected if each individual benefited simultaneously from maternal defense. However, if the maternal defense does not benefit the entire brood at the same time, the synchronized signaling may indicate another element of competition.
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