It's about Her: Male Within-Season Movements Are Related to Mate Searching in a Songbird

AbstractIn species with resource-defense mating systems (such as most temperate-breeding songbirds), male dispersal is often considered to be limited in both frequency and spatial extent. When dispersal occurs within a breeding season, the favored explanation is ecological resource tracking. In contrast, movements of male birds associated with temporary emigration, such as polyterritoriality (i.e., defense of an additional location after attracting a female in the initial territory), are usually attributed to mate searching. We suggest that male dispersal and polyterritoriality are functionally related and that mate searching may be a unifying hypothesis for predicting the within-season movements of male songbirds. Here, we test three key predictions derived from this hypothesis in Wood Warblers (Phylloscopus sibilatrix). We collected data on the spatial behavior of 107 males between 2017 and 2019 and related male movements to a new territory (in both a dispersal and a polyterritorial context) to mating potential in the current territory. Most males dispersed from their territories within days or weeks after failing to attract a female, despite occupying territories in apparently suitable habitat. Probability of polyterritoriality by paired males increased after the peak fertile period of their mate. Males never dispersed following nest predation if the female remained to renest. Thus, our data are consistent with the hypothesis that both movement types are functionally related to mate searching.

Habitat detection, habitat choice copying or mating benefits: What drives conspecific attraction in a nomadic songbird?

Conspecific attraction during habitat selection is common among animals, but the ultimate (i.e. fitness-related) reasons for this behaviour often remain enigmatic. We aimed to evaluate the following three hypotheses for conspecific attraction during the breeding season in male Wood Warblers (Phylloscopus sibilatrix): the habitat detection hypothesis, the habitat choice copying hypothesis and the female preference hypothesis. These hypotheses make different predictions with respect to the relative importance of social and nonsocial information during habitat assessment, and whether benefits accrue as a consequence of aggregation. We tested the above hypotheses using a combination of a 2-year playback experiment, spatial statistics and mate choice models. The habitat detection hypothesis was the most likely explanation for conspecific attraction and aggregation in male Wood Warblers, based on the following results: (1) males were attracted to conspecific song playbacks, but fine-scale habitat heterogeneity was the better predictor of spatial patterns in the density of settling males; (2) male pairing success did not increase, but instead slightly decreased, as connectivity with other males (i.e. the number and proximity of neighbouring males) increased. Our study highlights how consideration of the process by which animals detect and assess habitat, together with the potential fitness consequences of resulting aggregations, are important for understanding conspecific attraction and spatially clustered distributions.

First microsatellite markers for the European Robin (Erithacus rubecula) and their application in analysis of parentage and genetic diversity

The European Robin is a small passerine bird associated with woodlands of Eurasia and North Africa. Despite being relatively widespread and common, little is known of the species’ breeding biology and genetic diversity. We used Next Generation Sequencing (NGS) to develop and characterize microsatellite markers for the European Robin, designing three multiplex panels to amplify 14 microsatellite loci. The level of polymorphism and its value for assessing parentage and genetic structure was estimated based on 119 individuals, including seven full families and 69 unrelated individuals form Poland’s Białowieża Primaeval Forest and an additional location in Portugal. All markers appeared to be highly variable. Analysis at the family level confirmed a Mendelian manner of inheritance in the investigated loci. Genetic data also revealed evidence for extra-pair paternity in one family. The set of markers that we developed are proven to be valuable for analysis of the breeding biology and population genetics of the European Robin.

A review of conspecific attraction for habitat selection across taxa

Many species across taxa select habitat based on conspecific presence, known as conspecific attraction. Studies that document conspecific attraction typically provide social information (i.e., cues that indicate the presence of a given species) and then determine if a given species is more likely to settle at locations where the social information is provided compared to those locations that do not. Although the number of studies examining conspecific attraction has grown in recent years, a comprehensive review has not yet been undertaken. Here, we conducted a review of the literature and found 151 studies investigating conspecific attraction across eight taxa. We found that conspecific attraction is widespread with between 80% and 100% of studies, depending on taxa, documenting positive associations between habitat selection and the presence of conspecific cues. Conspecific attraction has been documented more frequently in bird and fish species with less attention given to invertebrate and mammal species. We use the patterns we found to (a) provide an overview of the current state of research on conspecific attraction and (b) discuss how important factors, such as cue characteristics and life history traits, may play a role in shaping conspecific attraction patterns within and across taxa.