Peak frequency and song amplitude in the presence and absence of noise playback in wild caught ad... more Peak frequency and song amplitude in the presence and absence of noise playback in wild caught adults
Minimum frequencies of each song type for birds singing in different noise treatments, after back... more Minimum frequencies of each song type for birds singing in different noise treatments, after background noise treatments changed in adulthood
ABSTRACT Previous intensive surveys on Floreana, the smallest inhabited island of the Galápagos a... more ABSTRACT Previous intensive surveys on Floreana, the smallest inhabited island of the Galápagos archipelago, in 2015 and 2016, produced reliable population estimates for all landbirds but failed to find 4 species that formerly occurred on the island: Gray Warbler Finch (Certhidea fusca), Vegetarian Finch (Platyspiza crassirostris), Little Vermilion Flycatcher (Pyrocephalus nanus), and Galápagos Rail (Laterallus spilonota). We revisited the island in February 2018 to extend our search to additional areas but again found none of the 4 lost species. As there is no longer any suitable habitat, we are certain that Galápagos Rail is now extinct on Floreana. It is possible that the remaining 3 species still survive in pockets of habitat that have not yet been surveyed. The very distinct subspecies of Gray Warbler-Finch (C. f. ridgwayi) especially merits further investigation.
Mean minimum frequency of each song type sung by each bird in the two treatment groups, with mean... more Mean minimum frequency of each song type sung by each bird in the two treatment groups, with mean minimum frequencies of the 9 tutor songs
It has been observed in many songbird species that populations in noisy urban areas sing with a h... more It has been observed in many songbird species that populations in noisy urban areas sing with a higher minimum frequency than do matched populations in quieter, less developed areas. However, why and how this divergence occurs is not yet understood. We experimentally tested whether chronic noise exposure during vocal learning results in songs with higher minimum frequencies in great tits (<i>Parus major</i>), the first species for which a correlation between anthropogenic noise and song frequency was observed. We also tested vocal plasticity of adult great tits in response to changing background noise levels by measuring song frequency and amplitude as we changed noise conditions. We show that noise exposure during ontogeny did not result in songs with higher minimum frequencies. In addition, we found that adult birds did not make any frequency or song usage adjustments when their background noise conditions were changed after song crystallization. These results challenge the common view of vocal adjustments by city birds, as they suggest that either noise itself is not the causal force driving the divergence of song frequency between urban and forest populations, or that noise induces population-wide changes over a time scale of several generations rather than causing changes in individual behaviour.
Minimum frequencies of all song types sung during 3, randomly selected 5 minute song bouts, repea... more Minimum frequencies of all song types sung during 3, randomly selected 5 minute song bouts, repeated in both noise treatment
SummaryWe documented the consequences of large-scale habitat loss on a community of Galápagos nat... more SummaryWe documented the consequences of large-scale habitat loss on a community of Galápagos native bird species on San Cristóbal island, based on point counts conducted between 2010 and 2017. Surprisingly, despite considerable habitat change and a variety of other threats, the landbirds of San Cristóbal have fared much better than on the neighbouring islands Floreana or Santa Cruz. While two species went extinct very soon after human colonisation, the majority have adapted well to subsequent vegetation change and habitat loss. The endemic San Cristóbal Mockingbird Mimus melanotis is more widespread than previously thought and its population seems to be stable since the 1980s. We thus propose a change in IUCN classification from ‘Endangered’ to ‘Near threatened’. We present evidence gained by interviewing locals which suggests that a small population of the Least Vermilion Flycatcher Pyrocephalus dubius, classified as ‘Extinct’ by BirdLife International, may have persisted until ve...
Proceedings of the Royal Society B: Biological Sciences
It has been observed in many songbird species that populations in noisy urban areas sing with a h... more It has been observed in many songbird species that populations in noisy urban areas sing with a higher minimum frequency than do matched populations in quieter, less developed areas. However, why and how this divergence occurs is not yet understood. We experimentally tested whether chronic noise exposure during vocal learning results in songs with higher minimum frequencies in great tits ( Parus major ), the first species for which a correlation between anthropogenic noise and song frequency was observed. We also tested vocal plasticity of adult great tits in response to changing background noise levels by measuring song frequency and amplitude as we changed noise conditions. We show that noise exposure during ontogeny did not result in songs with higher minimum frequencies. In addition, we found that adult birds did not make any frequency or song usage adjustments when their background noise conditions were changed after song crystallization. These results challenge the common view...
Peak frequency and song amplitude in the presence and absence of noise playback in wild caught ad... more Peak frequency and song amplitude in the presence and absence of noise playback in wild caught adults
Minimum frequencies of each song type for birds singing in different noise treatments, after back... more Minimum frequencies of each song type for birds singing in different noise treatments, after background noise treatments changed in adulthood
ABSTRACT Previous intensive surveys on Floreana, the smallest inhabited island of the Galápagos a... more ABSTRACT Previous intensive surveys on Floreana, the smallest inhabited island of the Galápagos archipelago, in 2015 and 2016, produced reliable population estimates for all landbirds but failed to find 4 species that formerly occurred on the island: Gray Warbler Finch (Certhidea fusca), Vegetarian Finch (Platyspiza crassirostris), Little Vermilion Flycatcher (Pyrocephalus nanus), and Galápagos Rail (Laterallus spilonota). We revisited the island in February 2018 to extend our search to additional areas but again found none of the 4 lost species. As there is no longer any suitable habitat, we are certain that Galápagos Rail is now extinct on Floreana. It is possible that the remaining 3 species still survive in pockets of habitat that have not yet been surveyed. The very distinct subspecies of Gray Warbler-Finch (C. f. ridgwayi) especially merits further investigation.
Mean minimum frequency of each song type sung by each bird in the two treatment groups, with mean... more Mean minimum frequency of each song type sung by each bird in the two treatment groups, with mean minimum frequencies of the 9 tutor songs
It has been observed in many songbird species that populations in noisy urban areas sing with a h... more It has been observed in many songbird species that populations in noisy urban areas sing with a higher minimum frequency than do matched populations in quieter, less developed areas. However, why and how this divergence occurs is not yet understood. We experimentally tested whether chronic noise exposure during vocal learning results in songs with higher minimum frequencies in great tits (<i>Parus major</i>), the first species for which a correlation between anthropogenic noise and song frequency was observed. We also tested vocal plasticity of adult great tits in response to changing background noise levels by measuring song frequency and amplitude as we changed noise conditions. We show that noise exposure during ontogeny did not result in songs with higher minimum frequencies. In addition, we found that adult birds did not make any frequency or song usage adjustments when their background noise conditions were changed after song crystallization. These results challenge the common view of vocal adjustments by city birds, as they suggest that either noise itself is not the causal force driving the divergence of song frequency between urban and forest populations, or that noise induces population-wide changes over a time scale of several generations rather than causing changes in individual behaviour.
Minimum frequencies of all song types sung during 3, randomly selected 5 minute song bouts, repea... more Minimum frequencies of all song types sung during 3, randomly selected 5 minute song bouts, repeated in both noise treatment
SummaryWe documented the consequences of large-scale habitat loss on a community of Galápagos nat... more SummaryWe documented the consequences of large-scale habitat loss on a community of Galápagos native bird species on San Cristóbal island, based on point counts conducted between 2010 and 2017. Surprisingly, despite considerable habitat change and a variety of other threats, the landbirds of San Cristóbal have fared much better than on the neighbouring islands Floreana or Santa Cruz. While two species went extinct very soon after human colonisation, the majority have adapted well to subsequent vegetation change and habitat loss. The endemic San Cristóbal Mockingbird Mimus melanotis is more widespread than previously thought and its population seems to be stable since the 1980s. We thus propose a change in IUCN classification from ‘Endangered’ to ‘Near threatened’. We present evidence gained by interviewing locals which suggests that a small population of the Least Vermilion Flycatcher Pyrocephalus dubius, classified as ‘Extinct’ by BirdLife International, may have persisted until ve...
Proceedings of the Royal Society B: Biological Sciences
It has been observed in many songbird species that populations in noisy urban areas sing with a h... more It has been observed in many songbird species that populations in noisy urban areas sing with a higher minimum frequency than do matched populations in quieter, less developed areas. However, why and how this divergence occurs is not yet understood. We experimentally tested whether chronic noise exposure during vocal learning results in songs with higher minimum frequencies in great tits ( Parus major ), the first species for which a correlation between anthropogenic noise and song frequency was observed. We also tested vocal plasticity of adult great tits in response to changing background noise levels by measuring song frequency and amplitude as we changed noise conditions. We show that noise exposure during ontogeny did not result in songs with higher minimum frequencies. In addition, we found that adult birds did not make any frequency or song usage adjustments when their background noise conditions were changed after song crystallization. These results challenge the common view...
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Papers by Erwin Nemeth