Canada jays (Perisoreus canadensis) balance protein and energy targets simultaneously in both consumed and cached food.

Food scarce periods pose serious physiological challenges for birds, especially in energetically demanding conditions. For species in the northern hemisphere, a decrease in available resources during winter adds further physiological stress to the energetic demands of life at low temperatures. Some species cache food to provide a reliable energy and nutrient resource during scarcity. Canada Jays are a year-round food-caching resident of the North American boreal forest. Canada Jays also rear their young prior to spring green up, making food caching not only essential for adult winter survival, but also potentially important for meeting the requirements of growing offspring in late winter and early spring. We examined the diet choices of Canada Jays immediately prior to winter, and the macronutrient composition of the foods Canada Jay consumed and cached at this time. We found that Canada Jays cache the same relative amounts of macronutrients as they consume but did not vary macronutrients seasonally. The similarities in the macronutrient proportions cached and consumed suggest a consistent nutrient intake pattern, and that Canada Jays are foraging to simultaneously meet similar minimum energy and minimum protein targets for both the present and future. These simultaneous targets constrain the caching decisions of jays when presented with dietary choices.

No evidence for future planning in Canada jays (Perisoreus canadensis).

In the past 20 years, research in animal cognition has challenged the belief that complex cognitive processes are uniquely human. At the forefront of these challenges has been research on mental time travel and future planning in jays. We tested whether Canada jays (Perisoreus canadensis) demonstrated future planning, using a procedure that has produced evidence of future planning in California scrub-jays. Future planning in this procedure is caching in locations where the bird will predictably experience a lack of food in the future. Canada jays showed no evidence of future planning in this sense and instead cached in the location where food was usually available, opposite to the behaviour described for California scrub-jays. We provide potential explanations for these differing results adding to the recent debates about the role of complex cognition in corvid caching strategies.

Black-capped chickadees (Poecile atricapillus) use temperature as a cue for reproductive timing.

Reliable environmental cues, such as photoperiod, act as initial predictive cues that allow birds to time reproduction to match peak food abundance for their offspring. More variable local cues, like temperature, may, however, provide more precise information about the timing of food abundance. Non-migratory birds, in particular, should be sensitive to temperature cues and use them to modulate their reproductive timing. We conducted two experiments to examine the effect of temperature on reproductive condition (gonad size and circulating androgen levels) in non-migratory black-capped chickadees (Poecile atricapillus). First, we exposed groups of birds in outdoor aviaries to three different over-winter temperature treatments and assessed gonad size in the spring. Second, we manipulated temperature in environmental chambers under photostimulatory and non-photostimulatory photoperiodic conditions and assessed gonad size and circulating testosterone levels. Temperature had no independent effect on gonad size or testosterone levels, but when photostimulated birds exposed to warmer conditions became reproductively ready earlier than birds experiencing cooler conditions. We conclude that temperature acts as a supplementary cue that modulates the photoperiod-driven timing of reproduction.

Overwinter temperature has no effect on problem solving abilities or responses to novelty in Black-capped Chickadees (Poecile atricapillus).

Birds overwintering at northern latitudes face challenging environments in which refined cognitive and behavioural responses to environmental stimuli could be a benefit. Populations of the same species from different latitudes have been shown to differ in their cognitive and behavioural responses, and these differences have been attributed to local adaptation. However, individuals overwintering at intermediate latitudes experience great breadth and variation in environmental conditions, and thus it is reasonable that these individuals would alter their responses based on current conditions. To determine within-species responses to environmental conditions we sampled birds from a single population at an intermediate latitude and assessed their problem solving abilities and their responses to novelty. We held birds overwinter in one of three experimental temperature regimes and assessed problem solving abilities and responses to novel stimuli in the spring. We found that overwinter temperature had no effect on problem solving ability. We also show that overwinter temperature had no effect on an individual's response to novelty. These findings strengthen the argument that differences in these behaviours seen at the population level are in fact driven by local adaptation, and that current environmental condition may have limited effects on these behaviours.