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The conversion of forest to agriculture is considered one of the greatest threats to avian biodiversity, yet how species respond to habitat modification throughout the annual cycle remains unknown. We examined whether forest bird associations with agricultural habitats vary throughout the year, and if species traits influence these relationships. Using data from the eBird community‐science program, we investigated associations between agriculturally‐modified land cover and the occurrence of 238 forest bird species based on three sets of avian traits: migratory strategy, dietary guild, and foraging strategy. We found that the influence of agriculturally‐modified land cover on species distributions varied widely across periods and trait groups but highlighting several broad findings. First, migratory species showed strong seasonal differences in their response to agricultural land cover while resident species did not. Second, there was a migratory strategy by season interaction; Neotropical migrants were most negatively influenced by agricultural land cover during the breeding period while short‐distance migrants were most negatively influenced during the non‐breeding period. Third, regardless of season, some dietary (e.g. insectivores) and foraging guilds (e.g. bark foragers) consistently responded more negatively to agricultural land cover than others (e.g. omnivores and ground foragers, respectively). Fourth, there were greater differences among dietary guilds in their responses to agricultural land cover during the breeding period than during the non‐breeding period, perhaps reflecting how different habitat and ecological requirements enhance the susceptibility of some guilds during reproduction. These results suggest that management efforts across the annual cycle may be oversimplified and thus ineffective when based on broad ecological generalisations that are static in space and time.
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Evaluating demographic habitat partitioning and its consequences during the non-breeding season in Loggerhead Shrikes
The non-breeding season is an understudied, yet likely critical, period for many species. Understanding species’ resource requirements, and determining when limited resources and increased densities may lead to intraspecific competition and demographic partitioning, may aid species conservation efforts. Monitoring species’ resource requirements during the non-breeding season may be more important in highly modified ecosystems, such as intensive agricultural landscapes, where anthropogenic pressures may further limit resources. The Loggerhead Shrike (Lanius ludovicianus) is a rapidly declining avian species that winters in agricultural areas in the southeastern United States, but little is known about their ecology or potential demographic partitioning in this context. To fill these knowledge gaps, we compared multi-scale habitat selection, survival, and space use across age and sex classes of shrikes inhabiting an agricultural landscape in Arkansas, USA. We found that habitat selection differed among demographic classes. Specifically, females preferred areas with more fallow cover, utility wires, and anthropogenic perches, whereas males preferred areas with more agricultural fields and ditches and less soybean cover. However, overall, shrikes exhibited numerous similarities in habitat selection, generally preferring areas with greater developed land cover (within a predominantly agricultural landscape), greater water availability, and taller perches. Despite the observed variability in habitat selection, no differences in apparent seasonal and annual survival rates or home range size existed among groups. However, non-breeding dispersal distance between years differed by age class, with older individuals being more site faithful than younger individuals. We suggest that the demographic habitat partitioning we detected may reflect adaptive differential life history strategies associated with age and sex classes, but further study of habitat selection by Loggerhead Shrikes across seasons and habitat types will help clarify the variation, importance, and potential carry-over effects of non-breeding habitat partitioning.
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- Award ID(s):
- 2151820
- PAR ID:
- 10615338
- Publisher / Repository:
- Association of Field Ornithologists, Wiley-Blackwell
- Date Published:
- Journal Name:
- Journal of Field Ornithology
- Volume:
- 95
- Issue:
- 2
- ISSN:
- 1557-9263
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.5751/JFO-00454-950201
