Data from: Discrimination behavior mediates foraging quality versus quantity trade-offs: nut choice in wild rodents

Discrimination, the ability to distinguish sensory stimuli and respond
accordingly, is a critical factor underscoring optimal foraging decisions.
Nevertheless, little is known about how mammals discriminate between
apparently similar foods of different quality. Here, we compared the
foraging behavior of Chinese white-bellied rats, Niviventer confucianus,
and Edwards’s long-tailed giant rats, Leopoldamys edwardsi, under natural
conditions in the field and in a captive enclosure without
predation/competition. We examined the behavioral processes involved in
discriminating between sound (i.e., undamaged) and insect larvae-infested
nuts of seguin chestnuts (Castanea seguinii) and demonstrated that both
rats could discriminate nut quality, where nut examination improved the
rats’ success rate at selecting sound nuts. Despite similar extents of
discrimination-derived benefit in both settings for each species,
differences between species-specific discrimination processes were
identified. Chinese white-bellied rats engaged in a higher relative
frequency and longer duration of nut examination in the enclosure than in
the wild. This indicates that they alter their feeding strategy to
trade-off selection for nut quality in captivity for a quantity-driven
strategy in the field. In contrast, giant rats showed a consistent
relative frequency of nut examination in both experimental settings. Their
fixed strategy balanced food quality and quantity primarily to maximize
caloric uptake without compromise when faced with predation or competition
risk. We posit that this behavioral difference in optimal foraging between
rat species is mediated by their differing, size-dependent energetic
requirements as well as the higher competition pressure and predation risk
faced by the approximately 8 times smaller white-bellied rats.