Social dominance has limited effects on spatial cognition in a wild food-caching bird

Social dominance has long been used as a model to investigate social stress. However, many studies using such comparisons have been performed in captive environments. These environments may produce unnaturally high antagonistic interactions, exaggerating the stress of social subordination and any associated adverse consequences. One such adverse effect concerns impaired cognitive ability, often thought to be associated with social subordination. Here, we tested whether social dominance rank is associated with differences in spatial learning and memory, and in reversal spatial learning (flexibility) abilities in wild food-caching mountain chickadees at different montane elevations. Higher dominance rank was associated with higher spatial cognitive flexibility in harsh environments at higher elevations, but not at lower, milder elevations. By contrast, there were no consistent differences in spatial learning and memory ability associated with dominance rank. Our results suggest that spatial learning and memory ability in specialized food-caching species is a stable trait resilient to social influences. Spatial cognitive flexibility, on the other hand, appears to be more sensitive to environmental influences, including social dominance. These findings contradict those from laboratory studies and suggest that it is critical to investigate the biological consequences of social dominance under natural conditions.

Seasonality of Food Use and Caching in New Zealand Robins (Petroica Australis)

<p>Foraging behaviour in birds is strongly determined by temporal factors such as season and time of day. Most birds show a limited number of food use methods such as consuming, feeding to conspecifics, or discarding. A relatively small number of birds also cache food for later use. The expression of caching in birds has been attributed to numerous factors. However, noting the environmental instability experienced by most caching species, researchers tend to cite survival of future food scarcity as the predominant advantage. Recording the food use behaviour of wild birds is typically difficult and time consuming, and many studies of north-temperate food-caching birds are limited by long caching distances, protracted caching durations, and a lack of year-round data. Additionally, food-caching in Australasian passerines has received limited quantification. The naïveté of the New Zealand robin (Petroica australis) makes it ideal for behavioural observations in the wild. Robins express a wide range of food use behaviours within close proximity of observers, and cached food is retrieved within a few days. Food use can be observed year-round in a temperate environment that is relatively stable. Thus, food use decisions in robins can be assessed in a wider context. In this study, behavioural data were collected from robins inhabiting the Karori Wildlife Sanctuary in Wellington. Robin behaviour was quantified by presenting monogamous, paired birds an ephemeral food resource and observing their responses. Seasonal variation in food use differed with sex and season. Birds mediated their food use in response to the presence of conspecifics. Males dominated food use year-round. During the breeding season, males cached little, mostly feeding familial conspecifics. However, non-breeding males selfishly cached food. Conversely, female caching propensity was mediated by courtship feeding during the breeding season, and the threat of male pilferage outside of it. Birds did not appear to anticipate future food scarcity. Instead, food was cached in the season in which retrieval would be least necessary. In robins, food is opportunistically cached, mainly as a competitive response to excess food.</p>

Seasonality of Food Use and Caching in New Zealand Robins (Petroica Australis)

<p>Foraging behaviour in birds is strongly determined by temporal factors such as season and time of day. Most birds show a limited number of food use methods such as consuming, feeding to conspecifics, or discarding. A relatively small number of birds also cache food for later use. The expression of caching in birds has been attributed to numerous factors. However, noting the environmental instability experienced by most caching species, researchers tend to cite survival of future food scarcity as the predominant advantage. Recording the food use behaviour of wild birds is typically difficult and time consuming, and many studies of north-temperate food-caching birds are limited by long caching distances, protracted caching durations, and a lack of year-round data. Additionally, food-caching in Australasian passerines has received limited quantification. The naïveté of the New Zealand robin (Petroica australis) makes it ideal for behavioural observations in the wild. Robins express a wide range of food use behaviours within close proximity of observers, and cached food is retrieved within a few days. Food use can be observed year-round in a temperate environment that is relatively stable. Thus, food use decisions in robins can be assessed in a wider context. In this study, behavioural data were collected from robins inhabiting the Karori Wildlife Sanctuary in Wellington. Robin behaviour was quantified by presenting monogamous, paired birds an ephemeral food resource and observing their responses. Seasonal variation in food use differed with sex and season. Birds mediated their food use in response to the presence of conspecifics. Males dominated food use year-round. During the breeding season, males cached little, mostly feeding familial conspecifics. However, non-breeding males selfishly cached food. Conversely, female caching propensity was mediated by courtship feeding during the breeding season, and the threat of male pilferage outside of it. Birds did not appear to anticipate future food scarcity. Instead, food was cached in the season in which retrieval would be least necessary. In robins, food is opportunistically cached, mainly as a competitive response to excess food.</p>

The Hippocampus uses cryptographic principles rather than plasticity to enable animals to secretly cache and retrieve their food

For animals, the ability to hide and retrieve valuable information, such as the location of food, can mean the difference between life and death. Here, we propose that to achieve this, their brain uses spatial cells similarly to how we utilize encryption for data security. Some animals are able to cache hundreds of thousands of food items annually by each individual and later retrieve most of what they themselves stashed. Rather than memorizing their cache locations as previously suggested, we propose that they use a single cryptographic-like mechanism during both caching and retrieval. The model we developed is based on hippocampal spatial cells, which respond to an animal's positional attention, such as when the animal enters a specific region (place-cells) or gazes at a particular location (spatial-view-cells). We know that the region that activates each spatial cell remains consistent across subsequent visits to the same area but not between areas. This remapping, combined with the uniqueness of cognitive maps, produces a persistent crypto-hash function for both food caching and retrieval. We also show that the model stores temporal information that helps animals in food caching order preference as previously observed. This behavior, which we refer to as crypto-taxis, might also explain consistent differences in decision-making when animals are faced with a large number of alternatives such as in foraging.

Neural representations of space in the hippocampus of a food-caching bird

Spatial memory in vertebrates requires brain regions homologous to the mammalian hippocampus. Between vertebrate clades, however, these regions are anatomically distinct and appear to produce different spatial patterns of neural activity. We asked whether hippocampal activity is fundamentally different even between distant vertebrates that share a strong dependence on spatial memory. We studied tufted titmice, food-caching birds capable of remembering many concealed food locations. We found mammalian-like neural activity in the titmouse hippocampus, including sharp-wave ripples and anatomically organized place cells. In a non–food-caching bird species, spatial firing was less informative and was exhibited by fewer neurons. These findings suggest that hippocampal circuit mechanisms are similar between birds and mammals, but that the resulting patterns of activity may vary quantitatively with species-specific ethological needs.