Limits...
Agriculture modifies the seasonal decline of breeding success in a tropical wild bird population.

Cartwright SJ, Nicoll MA, Jones CG, Tatayah V, Norris K - J Appl Ecol (2014)

Bottom Line: Agriculture modifies the seasonal decline in breeding success in this population.Our results suggest that forest restoration designed to reduce the detrimental impacts of agriculture on breeding may also help reduce the detrimental effects of breeding late due to wetter springs.Our results therefore highlight the importance of considering the interactive effects of environmental change when managing wild populations.

View Article: PubMed Central - PubMed

Affiliation: Centre for Agri-Environmental Research, School of Agriculture, Policy and Development, University of Reading Reading, RG6 6AR, UK.

ABSTRACT

Habitat conversion for agriculture is a major driver of biodiversity loss, but our understanding of the demographic processes involved remains poor. We typically investigate the impacts of agriculture in isolation even though populations are likely to experience multiple, concurrent changes in the environment (e.g. land and climate change). Drivers of environmental change may interact to affect demography, but the mechanisms have yet to be explored fully in wild populations.Here, we investigate the mechanisms linking agricultural land use with breeding success using long-term data for the formerly Critically Endangered Mauritius kestrel Falco punctatus, a tropical forest specialist that also occupies agricultural habitats. We specifically focused on the relationship between breeding success, agriculture and the timing of breeding because the latter is sensitive to changes in climatic conditions (spring rainfall) and enables us to explore the interactive effects of different (land and climate) drivers of environmental change.Breeding success, measured as egg survival to fledging, declines seasonally in this population, but we found that the rate of this decline became increasingly rapid as the area of agriculture around a nest site increased. If the relationship between breeding success and agriculture was used in isolation to estimate the demographic impact of agriculture, it would significantly under-estimate breeding success in dry (early) springs and over-estimate breeding success in wet (late) springs.Analysis of prey delivered to nests suggests that the relationship between breeding success and agriculture might be due, in part, to spatial variation in the availability of native, arboreal geckos.Synthesis and applications. Agriculture modifies the seasonal decline in breeding success in this population. As springs are becoming wetter in our study area and since the kestrels breed later in wetter springs, the impact of agriculture on breeding success will become worse over time. Our results suggest that forest restoration designed to reduce the detrimental impacts of agriculture on breeding may also help reduce the detrimental effects of breeding late due to wetter springs. Our results therefore highlight the importance of considering the interactive effects of environmental change when managing wild populations.

No MeSH data available.


Related in: MedlinePlus

Interactive effect of timing of breeding (first egg date) and area of agriculture within the breeding territory on breeding success. Surface shows predicted trend from parameters in Table1. Points show combinations of agriculture and timing in raw data with model predicted breeding success. First egg date scale is from 1 (1 September) to 113 (22 December). Graph made using the lattice package (Sarkar 2008).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4279951&req=5

fig01: Interactive effect of timing of breeding (first egg date) and area of agriculture within the breeding territory on breeding success. Surface shows predicted trend from parameters in Table1. Points show combinations of agriculture and timing in raw data with model predicted breeding success. First egg date scale is from 1 (1 September) to 113 (22 December). Graph made using the lattice package (Sarkar 2008).

Mentions: Of the 1581 eggs laid in first clutches within the study period, 722 survived to fledge. Agriculture had an adverse effect on breeding success in a simple GLMM ( = 3·96, P = 0·047) and in an interaction with the timing of breeding ( = 4·91, P = 0·027). The interactive effect was still apparent in the complex model ( = 4·28, P = 0·038; Table1), such that the seasonal decline in breeding success became progressively worse as the area of agriculture around a nest site increased (Fig.1). This interaction implies that if the relationship between breeding success and agriculture were used in isolation to estimate the demographic impact of agriculture, it would under-estimate breeding success in dry (early) springs and over-estimate it in wet (late) springs. We quantified this bias by using the complex model in Table1 to compare breeding success between wet, average and dry springs as the extent of agriculture increased (Fig.2). Our analysis showed that the bias is significant, representing up to a 38% under-estimate in dry springs and up to a 35% over-estimate in wet springs.


Agriculture modifies the seasonal decline of breeding success in a tropical wild bird population.

Cartwright SJ, Nicoll MA, Jones CG, Tatayah V, Norris K - J Appl Ecol (2014)

Interactive effect of timing of breeding (first egg date) and area of agriculture within the breeding territory on breeding success. Surface shows predicted trend from parameters in Table1. Points show combinations of agriculture and timing in raw data with model predicted breeding success. First egg date scale is from 1 (1 September) to 113 (22 December). Graph made using the lattice package (Sarkar 2008).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4279951&req=5

fig01: Interactive effect of timing of breeding (first egg date) and area of agriculture within the breeding territory on breeding success. Surface shows predicted trend from parameters in Table1. Points show combinations of agriculture and timing in raw data with model predicted breeding success. First egg date scale is from 1 (1 September) to 113 (22 December). Graph made using the lattice package (Sarkar 2008).
Mentions: Of the 1581 eggs laid in first clutches within the study period, 722 survived to fledge. Agriculture had an adverse effect on breeding success in a simple GLMM ( = 3·96, P = 0·047) and in an interaction with the timing of breeding ( = 4·91, P = 0·027). The interactive effect was still apparent in the complex model ( = 4·28, P = 0·038; Table1), such that the seasonal decline in breeding success became progressively worse as the area of agriculture around a nest site increased (Fig.1). This interaction implies that if the relationship between breeding success and agriculture were used in isolation to estimate the demographic impact of agriculture, it would under-estimate breeding success in dry (early) springs and over-estimate it in wet (late) springs. We quantified this bias by using the complex model in Table1 to compare breeding success between wet, average and dry springs as the extent of agriculture increased (Fig.2). Our analysis showed that the bias is significant, representing up to a 38% under-estimate in dry springs and up to a 35% over-estimate in wet springs.

Bottom Line: Agriculture modifies the seasonal decline in breeding success in this population.Our results suggest that forest restoration designed to reduce the detrimental impacts of agriculture on breeding may also help reduce the detrimental effects of breeding late due to wetter springs.Our results therefore highlight the importance of considering the interactive effects of environmental change when managing wild populations.

View Article: PubMed Central - PubMed

Affiliation: Centre for Agri-Environmental Research, School of Agriculture, Policy and Development, University of Reading Reading, RG6 6AR, UK.

ABSTRACT

Habitat conversion for agriculture is a major driver of biodiversity loss, but our understanding of the demographic processes involved remains poor. We typically investigate the impacts of agriculture in isolation even though populations are likely to experience multiple, concurrent changes in the environment (e.g. land and climate change). Drivers of environmental change may interact to affect demography, but the mechanisms have yet to be explored fully in wild populations.Here, we investigate the mechanisms linking agricultural land use with breeding success using long-term data for the formerly Critically Endangered Mauritius kestrel Falco punctatus, a tropical forest specialist that also occupies agricultural habitats. We specifically focused on the relationship between breeding success, agriculture and the timing of breeding because the latter is sensitive to changes in climatic conditions (spring rainfall) and enables us to explore the interactive effects of different (land and climate) drivers of environmental change.Breeding success, measured as egg survival to fledging, declines seasonally in this population, but we found that the rate of this decline became increasingly rapid as the area of agriculture around a nest site increased. If the relationship between breeding success and agriculture was used in isolation to estimate the demographic impact of agriculture, it would significantly under-estimate breeding success in dry (early) springs and over-estimate breeding success in wet (late) springs.Analysis of prey delivered to nests suggests that the relationship between breeding success and agriculture might be due, in part, to spatial variation in the availability of native, arboreal geckos.Synthesis and applications. Agriculture modifies the seasonal decline in breeding success in this population. As springs are becoming wetter in our study area and since the kestrels breed later in wetter springs, the impact of agriculture on breeding success will become worse over time. Our results suggest that forest restoration designed to reduce the detrimental impacts of agriculture on breeding may also help reduce the detrimental effects of breeding late due to wetter springs. Our results therefore highlight the importance of considering the interactive effects of environmental change when managing wild populations.

No MeSH data available.


Related in: MedlinePlus