Early-life sibling conflict in Canada jays has lifetime fitness consequences.

While delaying natal dispersal can provide short-term benefits for juveniles, lifetime fitness consequences are rarely assessed. Furthermore, competition for limited positions on a natal territory could impose an indirect fitness cost on the winner if the outcome has negative effects on its siblings. We use radio-tracking and 58 years of nesting data in Ontario, Canada to examine the lifetime fitness consequences of sibling expulsion in the Canada jay (Perisoreus canadensis). Six weeks after fledging, intra-brood dominance struggles result in one 'dominant juvenile' (DJ) remaining on the natal territory after expelling its subordinate siblings, the 'ejectees' (EJs). Despite an older age-at-first-reproduction, DJs produced more recruits over their lifetime and had higher first-year survival than EJs, leading to substantially higher direct fitness. Even though DJs incurred an indirect fitness cost by expelling their siblings and there was no evidence that their presence on the natal territory increased their parents' reproductive output the following year, they still had substantially higher inclusive fitness than EJs. Our results demonstrate how early-life sibling conflict can have lifetime consequences and that such fitness differences in Canada jays are driven by the enhanced first-year survival of DJs pursuant to the early-summer expulsion of their sibling competitors.

Cumulative cultural evolution and mechanisms for cultural selection in wild bird songs.

Cumulative cultural evolution, the accumulation of sequential changes within a single socially learned behaviour that results in improved function, is prominent in humans and has been documented in experimental studies of captive animals and managed wild populations. Here, we provide evidence that cumulative cultural evolution has occurred in the learned songs of Savannah sparrows. In a first step, "click trains" replaced "high note clusters" over a period of three decades. We use mathematical modelling to show that this replacement is consistent with the action of selection, rather than drift or frequency-dependent bias. Generations later, young birds elaborated the "click train" song form by adding more clicks. We show that the new songs with more clicks elicit stronger behavioural responses from both males and females. Therefore, we suggest that a combination of social learning, innovation, and sexual selection favoring a specific discrete trait was followed by directional sexual selection that resulted in naturally occurring cumulative cultural evolution in the songs of this wild animal population.

Flower plantings promote insect pollinator abundance and wild bee richness in Canadian agricultural landscapes.

Abstract: Global declines in pollinator populations are an ongoing concern from biodiversity and food security viewpoints. A growing conservation initiative in agricultural landscapes is the establishment of wildflowers on marginal lands to provide floral resources and habitat for pollinators. However, the effectiveness of such conservation and restoration efforts are not always assessed. We assessed the effectiveness of a private sector pollinator conservation initiative by (1) comparing insect abundance and richness between planted flower plots and control plots and (2) assessing changes between years. Over two years, planted flower plots and control plots (i.e. out-of-production farm areas) located in Canada were surveyed for insects using visual observation, netting, and pan trapping methods. Significantly more pollinators, especially wild bees, and higher wild bee richness were found in planted plots than control plots. Plot size had no effect on insect abundance and richness indicating that even small-scale flower plantings can provide benefits to pollinator communities. While pollinator, predator, and herbivore arthropod abundance and richness were stable or declined between years, likely due to adverse weather conditions in the second year of the study, wild bee abundance and richness increased over the same period. Our results support that flower plantings can be a successful conservation tool to increase pollinator and wild bee abundance and biodiversity within agricultural landscapes. Implications for insect conservation: Small-scale flower plantings within agricultural landscapes are a simple and effective conservation management strategy to support local insect pollinator populations. Supplementary Information: The online version contains supplementary material available at 10.1007/s10841-022-00400-8.

Timing of breeding carries over to influence migratory departure in a songbird: an automated radiotracking study.

1. Determining how events interact across stages of the annual cycle is critical for understanding the factors that affect individual fitness. However, there is currently little information detailing how breeding events influence migratory behaviour. 2. Using an automated digital telemetry array and an isolated island-breeding population of Savannah sparrows Passerculus sandwichensis, we provide the first direct evidence that the timing of breeding events carries over to influence the timing of migration in a songbird and assess for the first time how weather conditions on the breeding grounds also affect departure dates. 3. Date of migratory departure between September and October was strongly influenced by date of breeding completion in adults and fledging date in juveniles from June to July. 4. With respect to weather, adults departed during the first half of high-pressure systems, while juveniles departed throughout the entirety of high-pressure systems (including rainy evenings on the western edge of systems). 5. By combining both ecological and weather data, we could explain almost all variation in departure date for adults (95%), but weather conditions were not a good predictor of departure date for juveniles. 6. Our results provide strong evidence that the timing of breeding events is an important driver of migration timing and that exact departure dates are fine-tuned according to local weather conditions in adults, but not in juveniles.

Experimental evidence for a novel mechanism driving variation in habitat quality in a food-caching bird.

Variation in habitat quality can have important consequences for fitness and population dynamics. For food-caching species, a critical determinant of habitat quality is normally the density of storable food, but it is also possible that quality is driven by the ability of habitats to preserve food items. The food-caching gray jay (Perisoreus canadensis) occupies year-round territories in the coniferous boreal and subalpine forests of North America, but does not use conifer seed crops as a source of food. Over the last 33 years, we found that the occupancy rate of territories in Algonquin Park (ON, Canada) has declined at a higher rate in territories with a lower proportion of conifers compared to those with a higher proportion. Individuals occupying territories with a low proportion of conifers were also less likely to successfully fledge young. Using chambers to simulate food caches, we conducted an experiment to examine the hypothesis that coniferous trees are better able to preserve the perishable food items stored in summer and fall than deciduous trees due to their antibacterial and antifungal properties. Over a 1-4 month exposure period, we found that mealworms, blueberries, and raisins all lost less weight when stored on spruce and pine trees compared to deciduous and other coniferous trees. Our results indicate a novel mechanism to explain how habitat quality may influence the fitness and population dynamics of food-caching animals, and has important implications for understanding range limits for boreal breeding animals.