Landscape context mediates the physiological stress response of birds to farmland diversification.
Abstract
Farmland diversification practices are increasingly adopted to help reverse biodiversity declines in agroecosystems. However, evidence for the effectiveness of this approach often comes from documenting the species attracted to particular farming systems or landscapes, rather than their underlying physiological states that ultimately determine population growth or decline over the longer term. Across 38 organic, mixed-produce farms spanning the US west coast, we quantified three physiological biomarkers that are widely used to capture variation in short- and long-term stress responses for nine bird species with diverse life-history traits. While controlling for other potentially confounding variables, we used multilevel models to examine the association between bird physiological conditions, landscape context and local farm management practices, including the integration of livestock, and cropland composition and configuration. Birds generally had lower stress responses on more-locally diverse farms and in landscapes with higher amounts of semi-natural cover. However, interactions between farm diversity and landscape context suggested birds were less stressed on more diverse farms in simpler landscapes, but more stressed and in poorer condition on more diverse farms embedded within complex landscapes. We found no differences in stress responses among birds in relation to their degree of human association (synanthropy), which suggests generality in our findings.
Key words
- landscape
- wild birds
- animal behaviour
- biochemical markers
- biodiversity
- farm management
- farming
- farming systems
- interactions
- life history
- livestock
- population growth
- stress
- traits
- variation
- agricultural land
- stress response
- wild animals
- wildlife conservation
- human activity
- population decrease
- integrated systems
- domestic animals
- biological markers