Loss of flockmates weakens winter site fidelity in golden-crowned sparrows (\u3ci\u3eZonotrichia atricapilla\u3c/i\u3e)

Animal social interactions have an intrinsic spatial basis as many of these interactions occur in spatial proximity. This presents a dilemma when determining causality: Do individuals interact socially because they happen to share space, or do they share space because they are socially linked? We present a method that uses demographic turnover events as a natural experiment to investigate the links between social associations and space use in the context of interannual winter site fidelity in a migratory bird. We previously found that golden-crowned sparrows (Zonotrichia atricapilla) show consistent flocking relationships across years, and that familiarity between individuals influences the dynamics of social competition over resources. Using long-term data on winter social and spatial behavior across 10 y, we show that i) sparrows exhibit interannual fidelity to winter home ranges on the scale of tens of meters and ii) the precision of interannual site fidelity increases with the number of winters spent, but iii) this fidelity is weakened when sparrows lose close flockmates from the previous year. Furthermore, the effect of flockmate loss on site fidelity was higher for birds that had returned in more than 2 winters, suggesting that social fidelity may play an increasingly important role on spatial behavior across the lifetime of this migratory bird. Our study provides evidence that social relationships can influence site fidelity, and shows the potential of long-term studies for disentangling the relationship between social and spatial behavior

Winter GPS tagging reveals home ranges during the breeding season for a borealnesting migrant songbird, the Goldencrowned Sparrow

Determining space use for species is fundamental to understanding their ecology, and tracking animals can reveal insights into their spatial ecology on home ranges and territories. Recent technological advances have led to GPS-tracking devices light enough for birds as small as ~30 g, creating novel opportunities to remotely monitor fine-scale movements and space use for these smaller species. We tested whether miniaturized GPS tags can allow us to understand space use of migratory birds away from their capture sites and sought to understand both pre-breeding space use as well as territory and habitat use on the breeding grounds. We used GPS tags to characterize home ranges on the breeding grounds for a migratory songbird with limited available breeding information, the Golden-crowned Sparrow (Zonotrichia atricapilla). Using GPS points from 23 individuals across 26 tags (three birds tagged twice), we found home ranges in Alaska and British Columbia were on average 44.1 ha (95% kernel density estimate). In addition, estimates of territory sizes based on field observations (mean 2.1 ha, 95% minimum convex polygon [MCP]) were three times smaller than 95% MCPs created using GPS tags (mean 6.5 ha). Home ranges included a variety of land cover classes, with shrubland particularly dominant (64–100% of home range cover for all but one bird). Three birds tracked twice returned to the same breeding area each year, supporting high breeding site fidelity for this species. We found reverse spring migration for five birds that flew up to 154 km past breeding destinations before returning. GPS-tracking technology allowed for critical ecological insights into this migratory species that breeds in very remote locations

A migratory sparrow has personality in winter that is independent of other traits

Small birds in winter face trade-offs between predation risk and foraging, and alternate life-history strategies may arise from these trade-offs. Animal personality shows similarities with alternative life-history strategies, and using a life-history context to understand personality can provide valuable insights. Golden-crowned sparrows, Zonotrichia atricapilla, a small migratory bird, have a complex winter social system with high site-fidelity, long-term social associations between individuals and competition mediated by badges of status. We asked whether golden-crowned sparrows show personalities during winter, whether these personalities were consistent over 3 years and whether they correlated with social and morphological traits. We found that golden-crowned sparrows had highly repeatable behaviours, as measured in captive behavioural assessments, constituting personalities consistent within one season and over time for up to 3 years, a time span that covers the average life span of the sparrows. While long-term repeatability was present, it varied considerably among different behaviours and time spans, and length of time between measures did not predict the magnitude of repeatability. Two movement-based aspects of sparrow personality were independent of the traits we measured (dominance, badges of status, size and age). However, nonsong vocalizations (a repeatable aspect of personality) correlated with wing length and gold badge size in some years. Because personality did not strongly link to the social traits we measured, sparrow personality could represent a separate axis of variation that might connect with other winter life-history parameters such as foraging, predation response or survival

GCSP_FamUn_DataArchive.xlsx

Data for article in Ecology Letters by Chaine, Shizuka, Block, Zhang, and Lyon entitled "<b>Manipulating badges of status only fools strangers"</b