Geographic variation in call structure, likelihood, and call-song associations across subspecies boundaries, migratory patterns, and habitat types in the Marsh Wren (Cistothorus palustris)

Abstract

Geographic variation in acoustic signals can be important in species divergence, especially the maintenance of prezygotic barriers to gene flow. Furthermore, selective pressures on acoustic signals likely vary both across geographic distances and among vocalizations used in different behavioral contexts. We described the call repertoire of 5 subspecies of Marsh Wren (Cistothorus palustris) in eastern North America and tested for variation in both the acoustic structure and likelihood of production of each call type at 3 functional-ecological levels: subspecies identity, migratory pattern, and habitat type. Three of the 7 described call types exhibited acoustic variation best explained by either migratory pattern or habitat type. These calls were used principally in courtship-territorial patrol contexts, whereas 4 calls that did not exhibit geographic variation were used in agonistic interactions. How often a call is used in a population may be indicative of the behavior or breeding phenology associated with that vocalization. We found that 4 calls varied in how commonly they were produced among the subspecies and/or habitat types. We also described and quantified the degree to which these 5 subspecies produce calls in association with song-a little reported, but possibly more widespread, behavior in birds. Marsh Wrens commonly embedded 3 call types into song in a nonrandom pattern. This behavior was more common in freshwater-marsh populations than in saltmarsh populations, and we discuss several possible functions for call-song associations. Overall, when geographic variation in call structure occurred, it was most commonly explained by differences in habitat type and, therefore, may be indicative of local adaptations that could limit gene flow across environments.

Interspecific competition between two partridges in farmland landscapes

“…This analysis was performed using the MASS R package (Ripley, 2017). To handle the differences in sample sizes between the two situations (alone or co-occurrence) given the low sample size of the "co-occurrence" category, we produced 95% confidence intervals (CI) for linear discriminant scores following Luttrell & Lohr (2018).…”

Black Grouse Hissing Calls Show Geographic Variability across the Distribution Area

“…Studies on the topic of geographical variability in bird acoustic performance have been performed for both song-learning species [61][62][63][64][65][66], and species with innate vocaliza-…”

“…Studies on the topic of geographical variability in bird acoustic performance have been performed for both song-learning species [61][62][63][64][65][66], and species with innate vocalizations, including orders Gruiformes, Psittaciformes, and Sphenisciformes [67][68][69][70]. Although there have been cases with landfowl that suggest that the evolution of vocal expression in these species may also be affected by encounters [71], it is thought that the black grouse does not belong to the group of song-learning birds.…”

Geographic Variation in Note Types of Alarm Calls in Japanese Tits (Parus minor)

“…Unlike song, which involves learning and therefore includes a cultural component in its vertical and horizontal transmission within oscine passerines (‘‘songbirds’’), bird calls have long been thought to be relatively impervious to experiential background [ 2 ]. Studying calls, therefore, introduces the opportunity to understand patterns of divergence in functionally and acoustically distinct signals that may be subject to different types of selection [ 15 ].…”

“…Geographic variation has been documented for bird calls [ 15 , 16 , 17 , 18 ], but most have focused on contact calls. Meanwhile, geographic variations in avian alarm calls have been thus far neglected.…”