. The Canadian field-naturalist. 212 The Canadian Field-Naturalist Vol. 97 crackers first placed seeds in their pouches on 15 August in 1980 and 26 August in 1978, respectively. The first juvenile observed putting seeds into its sub- lingual pouch did so on 7 September, but this behav- ior was not commonly observed until 23 September. Although seed caching behavior in corvids appears to be innate (Ligon and Martin 1974), juvenile nut- crackers in the years of this study did not begin to store seeds until 2-3 weeks after adults had begun to do so. Juvenile Aggression We observed 145 aggressive
. The Canadian field-naturalist. 212 The Canadian Field-Naturalist Vol. 97 crackers first placed seeds in their pouches on 15 August in 1980 and 26 August in 1978, respectively. The first juvenile observed putting seeds into its sub- lingual pouch did so on 7 September, but this behav- ior was not commonly observed until 23 September. Although seed caching behavior in corvids appears to be innate (Ligon and Martin 1974), juvenile nut- crackers in the years of this study did not begin to store seeds until 2-3 weeks after adults had begun to do so. Juvenile Aggression We observed 145 aggressive interactions among nutcrackers foraging on Pinon Pine in 1980. In 106 of these, the ages of both participants were determined. Adults interacted aggressively 71 times, adults were aggressive toward juveniles 6 times, and juveniles were aggressive towards adults 29 times. To test whether the observed frequency of interactions between age classes was significantly different from random, we calculated expected frequencies of interactions using a binomial distribution. We assumed that the propor- tion of adults (p) in the population was This value was selected for two reasons: 1) it approximated the actual proportion of adults on our study site at the time the data were collected and 2) this value gives the highest probability of failing to reject the null hypothesis (, aggressive interactions between age classes were random). Juveniles were aggressive toward adults more frequently than predicted by chance (A:^= , P Ad o—-o juv-> Ad o—o Ad->Juv. Figure 2. Aggressive interactions per observation hour (adjusted to adult-juvenile ratio of 80:20, see text) between adult and juvenile nutcrackers foraging on Piflon Pine from 19 August 4 October 1980. Infrequent adult-adult aggression continued into Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of th
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