01931nas a2200193 4500008004100000245009400041210006900135520130600204653001401510653001701524653002101541653002001562653002101582653001801603653001701621100002901638700002401667856004601691 2019 eng d00aHow Early Do Birds Start Chirping? Dawn Chorus Onset and Peak Times in a Neotropical City0 aHow Early Do Birds Start Chirping Dawn Chorus Onset and Peak Tim3 a

Urbanisation poses important challenges for animal communication. Avian dawn choruses are a prominent component of urban soundscapes and have received attention in recent urban ecology studies. Current evidence based on comparisons of urban and non-urban sites suggest that urbanisation is associated with earlier dawn chorus singing activity. However, this phenomenon remains mainly unexplored in tropical cities. We here assessed dawn chorus onset and peak times in two contrasting conditions of the urbanisation intensity gradient (i.e., intra-urban and peri-urban forested areas) of a Neotropical city, Xalapa in Mexico, assessing relationships with noise at sunrise and artificial light at night. We found no differences in dawn chorus onset or singing peak times when contrasting intra- and peri-urban areas. However, we found non-significant trends for earlier chorus onsets and peak times with increasing noise levels. Our results show no relationship between artificial light at night and dawn chorus timing, adding evidence to recent studies showing that light pollution does not seem to be determinant in the dawn choruses of tropical birds. Further research is needed to include a wider array of urbanisation conditions and drivers of the singing routines of urban tropical birds.

10abehaviour10abioacoustics10abird assemblages10amorning singing10aperi-urban areas10aUrban ecology10aurbanisation1 aMarín-Gómez, Oscar, H.1 aMacGregor-Fors, Ian uhttps://bio.acousti.ca/zh-hans/node/5839502352nas a2200205 4500008004100000245010300041210006900144520163500213653001901848653002501867653001501892653002701907653001801934100002901952700002101981700002502002700002802027700002402055856006702079 2020 eng d00aWhere has the city choir gone? Loss of the temporal structure of bird dawn choruses in urban areas0 aWhere has the city choir gone Loss of the temporal structure of 3 a

Living in the city represents a great challenge for organisms that are exposed to the novel environmental conditions inherent to urbanization. Recent studies have highlighted the ecological impact that urbanization poses on the acoustic phenotype and singing routines of birds. However, the organization and structure of avian dawn choruses in urban settings remains largely unexplored. In this study, we assessed the temporal structure of avian dawn choruses in an intra-urban area and a peri-urban forest using bipartite network analyses. We predicted a random network structuring of dawn choruses across time at the intra-urban area, while expected a non-random structure (i.e., modular or nested) at the peri-urban forest. While we detected different groups of birds vocalizing together temporarily, following a modular pattern in both studied conditions, only the one from the peri-urban forest showed a sequential temporal structure of dawn choruses. Avian dawn choruses from both intra-urban and peri-urban areas were mainly comprised by phylogenetically unrelated species (i.e., random phylogenetic structure), also exhibiting low overlap on singing frequencies. Our results are in agreement with the temporal partitioning of the acoustic space in the peri-urban forest. Our findings also suggest that the absence of temporally-structured modules of bird dawn choruses at heavily-urbanized areas could be related to the depauperization of the avian community at intra-urban areas as a sequel of ecological filtering, as well as the consequent importance of the dominance of the acoustic space by invasive species.

10aAcoustic space10aEcological filtering10aModularity10aMulti-species choruses10aUrban ecology1 aMarín-Gómez, Oscar, H.1 aDáttilo, Wesley1 aSosa-López, Roberto1 aSantiago-Alarcon, Diego1 aMacGregor-Fors, Ian uhttps://linkinghub.elsevier.com/retrieve/pii/S016920461830532202516nas a2200217 4500008004100000245010300041210006900144260001600213490000700229520180700236653002502043653002402068653001302092653001402105653002202119653001802141653001702159100002502176700002402201856007302225 2019 eng d00aHabitat-related differences in song structure and complexity in a songbird with a large repertoire0 aHabitatrelated differences in song structure and complexity in a cJan-12-20190 v193 a

Background

Urbanisation has been shown to influence many aspects of animal vocal communication. Much attention has been paid to anthropogenic noise, which is often described as one of the most challenging disturbances for urban dwellers. While a large body of literature describes associations between vocal behavior of avian populations and background noise level, most of these studies were conducted on species with relatively simple songs and small repertoire sizes. This study focuses on the song thrush, Turdus philomelos, a common Eurasian songbird with a complex singing style and large syllable repertoire. Our objective was to determine whether frequency, repertoire and temporal organisation of song parameters vary between birds inhabiting urban and adjacent forest habitats in which ambient noise levels differ.

Results

Songs of urban males were found to be more complex than in conspecifics from natural forest populations. Urban dwellers possessed greater syllable repertoires and repeated syllable sequences more often. In addition, they used a smaller proportion of whistles and a higher proportion of twitter syllables when singing compared to the nonurban males. Moreover, we found significant differences in the minimum and peak frequency of the whistle syllable between studied populations.

Conclusions

These findings may be an example of adaptation of acoustic communication in noisy urban environments, but we also discuss other possible explanations. We emphasize the need for further investigation into the relationships between birdsong and habitat characteristics, male quality, population density and ambient noise level in populations occupying urban and nonurban habitats.

10aanimal communication10aanthropogenic noise10abirdsong10asongbirds10aTurdus philomelos10aUrban ecology10aurbanisation1 aDeoniziak, Krzysztof1 aOsiejuk, Tomasz, S. uhttps://bmcecol.biomedcentral.com/articles/10.1186/s12898-019-0255-7