Development of species preferences in two hamsters, Phodopus campbelli andPhodopus sungorus: Effects of cross-fostering

Experiments were conducted to investigate species-specific preferences in t wo closely related species of hamsters, Phodopus campbelli and Phodopus sun gorus. Male hamsters that were raised with conspecifics spent more time inv estigating an anaesthetized conspecific male than a heterospecific male, an d also spent more time investigating odours of conspecifics than those of h eterospecifics (midventral gland, urine, and saccular secretion). Cross-fos tered P. sungorus males reversed their normal preferences, spending more ti me investigating stimuli (anaesthetized males and all three odours) of the foster species. Cross-fostered P. campbelli males also investigated an anae sthetized male of the foster species more than a male of their own species, but did not show a preference for odours alone. Social experience during t he 15 d immediately following weaning also influenced these preferences. If exposures during and after nesting were to heterospecifics the preference for heterospecifics was strengthened; if either period of experience was wi th a conspecific, this eliminated the preference for heterospecifics in P. sungorus but did not influence the lack of a preference in P. campbelli. Th us, early experience during both the nestling stage and the 15 d after wean ing influenced responses to species-typical cues in both species, but it ha d a more pronounced effect in P. sungorus.