bioRxiv Science⌕ Search
Home/Archive/bioRxiv

bioRxiv · 10.1101/741413

Migrant semipalmated sandpipers (Calidris pusilla) have over four decades steadily shifted towards safer stopover locations

Hope, D. D.·Lank, D. B.·Smith, P. A.·Paquet, J.·Ydenberg, R. C.
View original source ↗Export metadata ↓

Abstract

Peregrine falcons (Falco peregrinus) have undergone a steady hemisphere-wide recovery since the ban on DDT in 1973, resulting in an ongoing increase in the level of danger posed for migrant birds, such as Arctic-breeding sandpipers. We anticipate that in response migrant semipalmated sandpipers (Calidris pusilla) have adjusted migratory behaviour, including a shift in stopover site usage towards locations offering greater safety from falcon predation. We assessed semipalmated sandpiper stopover usage within the Atlantic Canada Shorebird Survey dataset. Based on 3,030 surveys (totalling [~]32M birds) made during southward migration, 1974 - 2017, at 198 stopover locations, we assessed the spatial distribution of site usage in each year (with a priority matching distribution index, PMD) in relation to the size (intertidal area) and safety (proportion of a sites intertidal area further than 150m of the shoreline) of each location. The PMD index value is > 1 when usage is concentrated at dangerous locations, 1.0 when usage matches location size, and < 1 when usage is concentrated at safer locations. A large majority of migrants were found at the safest sites in all years, however our analysis of the PMD demonstrated that the fraction using safer sites increased over time. In 1974, 80% of birds were found at the safest 20% of the sites, while in 2017, this had increased to 97%. A sensitivity analysis shows that the shift was made specifically towards safer (and not just larger) sites. The shift as measured by a PMD index decline cannot be accounted for by possible biases inherent in the data set. We conclude that the data support the prediction that increasing predator danger has induced a shift by southbound migrant semipalmated sandpipers to safer sites.

Source connections

Explore related subjects

animal behavior and cognitionPreprint

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

Hope, D. D., Lank, D. B., Smith, P. A., Paquet, J., Ydenberg, R. C.. 2019-08-31. Migrant semipalmated sandpipers (Calidris pusilla) have over four decades steadily shifted towards safer stopover locations. https://doi.org/10.1101/741413

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related preprints

bioRxiv2026

Behavioral divergence across replicated predation regimes is species-specific in two sympatric poeciliid fishes

Predation is a potent driver of behavioral divergence across prey populations, yet whether shared predation regimes generate similar responses in coexisting prey species remains unclear. Species differences in reproductive and foraging traits may alter vulnerability to predators, generating species-specific responses. We compared behavior and cognition of two poeciliid fishes (Gambusia affinis and Poecilia latipinna) that differ in body size, the presence of male ornamentation, and mating tactics. We sampled both species across replicate high- and low-predation regimes and measured exploration, shyness, boldness, social motivation, and detour solve latency (N = 509). Multivariate behavior and cognition differed between predation regimes, and the magnitude of divergence varied with species but not body size. Consistent with the multivariate pattern, the more conspicuous P. latipinna exhibited higher boldness and overall lower exploration under high-predation, while high- and low-predation populations of G. affinis did not differ. These findings suggest either that the more conspicuous species experiences greater predation risk or that the less conspicuous species reduces its predation risk through alternative phenotypic responses. More broadly, species differences in reproductive phenotypes associated with sexual selection may help explain why shared predation regimes generate variable patterns of behavioral divergence across taxa.

animal behavior and cognition↗
bioRxiv2026

Capturing the rhythm: methodological choices shape inference from circadian activity data

Abstract 1. Statistical tools and analytical decisions for analysing animal activity data are often limited and poorly justified, particularly with respect to model choice, sampling design and temporal aggregation. These shortcomings can constrain our ability to draw accurate and biologically meaningful inferences about behaviour. 2. We interrogated 24 h activity data taken from individual males and females derived from five Drosophila melanogaster populations to generate a general framework for collecting and analysing activity data that systematically compares common model classes, continuous verses fragmented sampling strategies, and alternative temporal aggregation choices (time-bin sizes). 3. Our analyses identified generalised additive mixed models (GAMMs) applied to high-frequency continuous data with small-moderate bin sizes (1-5 minutes) as providing the most robust and interpretable inference for our complex, high-frequency activity data. 4. However, our interrogation of the data set confirmed that analytical and sampling decisions need to be tailored to the study species, the timing of activities and the nature of the behaviour of interest. Accordingly, polynomial and cosinor generalised linear models, increased but biologically targeted snapshot sampling, and bin sizes smaller than one hour yielded adequate analyses with similar biological conclusions when appropriately matched to the system. 5. Our approach provides an accessible decision-making framework for activity analyses that allows researchers across behavioural, ecological and evolutionary studies to justify and optimise choices about data collection and modelling. Such an approach improves the biological relevance of inference and supporting the use of modern tracking and analytical technologies.

animal behavior and cognition↗
bioRxiv2026

Greylag geese (Anser anser) initiate group flight based on the number and identities of callers

Social animals need to maintain cohesion when they move, and movement decisions are influenced by social organization and ecological or individual needs. To maintain synchrony during collective movement, the use of signals, including vocal signals, is often necessary. Greylag geese are gregarious and vocal before and during flight. We observed instances of naturally occurring flight initiation attempts in a free-living population of greylag geese -n = 133 birds- to investigate the decision-making process in this species, including the role vocalisations play in flight decisions. We recorded the number of participants in flight-initiation attempts, their vocal behaviour -using two call types specific to flight initiation signalling: Locomotion and Pre-flight calls-, the outcome of those attempts, in addition to the resulting flying group size and composition. We found that the identities and number of flock members joining in the calling chorus predicted both the probability of successful flight and the resulting flying group size. The number of Locomotion callers was associated with an increased probability of success, as well as larger flying group size, including both family and non-family fliers. The number of Pre-flight callers was also associated with a higher probability of successful flight, but its effect on the increase in flying group size was marginal. Successful departures were more probable when the family members of the initiator responded vocally. Overall, our findings are consistent with a system where the decision to fly is made individually using two distinct vocal signals to estimate the number of voters and at least the identities of social partners and progeny. In species where temporal and spatial group cohesion varies both seasonally and diurnally, individuals priorities appear to be maintaining proximity to mates and family members, followed by maximizing the size of flight groups.

animal behavior and cognition↗