Phenotypic differences among wild passerine nestlings in relation to early-life rearing environment

2021 ◽  
Author(s):  
Jesús Gómez ◽  
Christy Morrissey ◽  
Sonia Cabezas ◽  
Tracy Marchant ◽  
Robert Clark
Keyword(s):  
Land Use ◽  
Body Condition ◽  
Early Life ◽  
Agricultural Land ◽  
Developmental Stages ◽  
Tree Swallow ◽  
Phenotypic Differences ◽  
Aerial Insectivore ◽  
Fledgling Survival ◽  
Insect Populations

Subtle changes in stress physiology during critical developmental stages have been linked to long-term fitness; however, the biological processes and phenotypic responses to early-life rearing environments such as anthropogenic land use conditions, have not been fully evaluated in insectivorous birds. We manipulated Tree Swallow, Tachycineta bicolor (Vieillot, 1808), brood sizes at sites with contrasting agricultural land use to assess phenotypic changes in body condition and genetic and physiological biomarkers of stress during the sensitive nestling growth phase. We predicted that nestling swallows raised on cropland-dominated sites, especially those in enlarged broods, would have lower body condition, shorter telomeres, and higher feather corticosterone than nestlings raised in smaller broods at grassland sites. Body condition was highest among nestlings raised in reduced broods but was unrelated to land use. Telomere lengths tended to be shorter in nestlings from enlarged broods and at cropland sites. Corticosterone was not related to any factor. Locally-abundant insect populations associated with wetlands may have dampened the effects and/or parent swallows assumed higher costs of reproduction rather than passing these costs to nestlings. Results suggest that food stress could reduce fledgling survival via telomere shortening; a hypothesis that requires further investigation due to its potential importance to population viability in multiple declining aerial insectivore species.

Agricultural land use alters trophic status and population density of deer mice (Peromyscus maniculatus) on the North American Great Plains

2012 ◽  
Vol 90 (7) ◽  
pp. 868-874 ◽  
Author(s):  
A.J. White ◽  
R.G. Poulin ◽  
B. Wissel ◽  
J.L. Doucette ◽  
C.M. Somers
Keyword(s):  
Land Use ◽  
Population Density ◽  
Body Condition ◽  
Trophic Level ◽  
Trophic Status ◽  
Agricultural Land ◽  
Peromyscus Maniculatus ◽  
Deer Mice ◽  
Agricultural Land Use ◽  
Native Prairie

Habitat conversion is among the most important causes of environmental change worldwide, yet relatively little is known about its potential influence on trophic interactions. We investigated the effects of agricultural land use on carbon and nitrogen stable isotope values, trophic status, population density, and body condition of deer mice ( Peromyscus maniculatus (Wagner, 1845)) in a grassland ecosystem. Muscle δ15N (cropland = 7.6‰ ± 1.3‰; hay fields = 7.9‰ ± 1.3‰; native prairie = 7.2‰ ± 2.1‰) from deer mice did not vary with land use despite baseline soil and vegetation δ15N differences. Enrichment of deer mice over vegetation (Δδ15N) was, on average, a full trophic level (~2.5‰) higher on native prairie (6.4‰ ± 1.6‰) than on cropland (3.9‰ ± 2.3‰), and intermediate in hay fields (5.9‰ ± 2.0‰). Relative density of deer mice was more than twofold higher in crop and hay fields compared with native prairie, but body condition did not vary with land use. Our results suggest that agricultural activity caused a shift in the trophic level and relative abundance of a generalist grassland omnivore. Soil and vegetation δ15N reflected anthropogenic N inputs to agricultural fields but were not useful as general markers of habitat use in this study.

Tree Swallow (Tachycineta bicolor) foraging responses to agricultural land use and abundance of insect prey

2016 ◽  
Vol 94 (9) ◽  
pp. 637-642 ◽  
Author(s):  
R.L. Stanton ◽  
C.A. Morrissey ◽  
R.G. Clark
Keyword(s):  
Land Use ◽  
Foraging Behaviour ◽  
Agricultural Land ◽  
Tachycineta Bicolor ◽  
Tree Swallow ◽  
Agricultural Land Use ◽  
Tree Swallows ◽  
Rfid Technology ◽  
Insect Abundance ◽  
Insect Prey

Throughout North America, many species of aerial insectivorous birds have exhibited steep declines. The timing of these declines coincides with changes in agriculture, perhaps signaling a causal link. Increased agrochemical use, wetland drainage, and cropping intensity may indirectly influence insectivores by reducing the abundance of insect prey. Our objective was to determine whether changes in insect abundance and biomass on agricultural landscapes in the Canadian Prairies influence the foraging behaviour of breeding Tree Swallows (Tachycineta bicolor (Vieillot, 1808)). Swallows were studied at five sites with varying levels of agricultural intensity in Saskatchewan, where insect abundance and biomass were monitored daily with passive aerial samplers. Radio-frequency identification (RFID) technology was employed at Tree Swallow nest boxes to investigate adult foraging behaviour. Foraging rates (number of nest visits/h) were slightly higher on agricultural sites than at grassland sites, and were positively related to daily insect biomass and nestling age. Tree Swallows, especially males, breeding at agricultural sites spent more time away from the nest box, presumably foraging, resulting in reduced nest attentiveness. RFID technology provides an effective technique to measure behaviour in birds and these findings suggest mechanisms by which prey abundance and agricultural land use may affect declining aerial insectivorous bird populations.

scholarly journals Negative effects of agricultural intensification on energetic gain rates of a declining aerial insectivore

2021 ◽  
Author(s):  
Daniel R. Garrett ◽  
Fanie Pelletier ◽  
Dany Garant ◽  
Marc Bélisle
Keyword(s):  
Body Condition ◽  
Agricultural Intensification ◽  
Agricultural Practices ◽  
Agricultural Landscapes ◽  
Tree Swallow ◽  
Food Provisioning ◽  
Negative Effects ◽  
Aerial Insectivore ◽  
Provisioning Behavior ◽  
Breeding Grounds

AbstractThe historical rise of intensive agricultural practices is hypothesized to be related to declines of grassland and aerial insectivorous birds. Drivers of declines may also influence the overall abundance and spatial distribution of insects within agricultural landscapes. Subsequently, average energetic gain rates of birds breeding within more agro-intensive landscapes may be impacted. Lower energetic gain rates in agro-intensive landscapes may lead to reduced growth rate, body condition or fledging success of nestlings but also to diminished body condition of food provisioning adults. In this study, we assessed if energetic gain of nestlings and food provisioning behavior of adults varied across a gradient of agricultural intensification in a declining aerial insectivore, the Tree swallow (Tachycineta bicolor). We found that hourly gain rate was lower in agro-intensive landscapes, and yet travel distances were longest within less agro-intensive landscapes. Our results highlight that, in order to maximize long term average gain rates, Tree swallows breeding within agro-intensive landscapes must forage with greater intensity, perhaps at a cost to themselves, or else costs will transfer to growing broods. Our work provides further evidence that agricultural intensification on the breeding grounds can contribute to the declines of aerial insectivores in part through a trophic pathway.

scholarly journals Spatial variability of soil erodibility in response to different agricultural land use at highland farms

2021 ◽  
Vol 34 ◽  
pp. 41-53
Author(s):  
Nuraddeen M. Nasidi ◽  
Aimrun Wayayok ◽  
Ahmad F. Abdullah ◽  
Muhamad S.M. Kassim ◽  
Nura J. Shanono
Keyword(s):  
Land Use ◽  
Spatial Variability ◽  
Agricultural Land ◽  
Developmental Stages ◽  
Agricultural Land Use ◽  
Soil Erodibility ◽  
Cameron Highlands ◽  
Soil Disturbances ◽  
Spatial Locations ◽  
Low K

This work describes the effect of different agricultural land use on potential soil erodibility (K) at cultivated farming areas in Cameron Highlands. Ordinarily, soils are assigned with K factors depending on geological properties only which can result into erroneous calculation of soil erosion. This study explores roles of different agricultural land use on the spatial variability of soil erodibility on hilly farms at Cameron Highlands. Soil samples, slopes and spatial locations were collected based on crop types being cultivated. Meanwhile, the land use and type of equipment for each crop are recorded and ranked depending on the degree of soil disturbances. The results showed that, K values are ranged from 0.0084 to 0.0161. Shallow-root crops, such as vegetables and flowers have higher K values due to shallow soil rootzone and frequency of surface operations. However, tea cultivated areas and forests have low K values, indicating comparably higher ability to resist erosion. Furthermore, the erodibility factor for tea farms shows increasing patterns along the developmental stages while the reverse was found in vegetable farms. Spatial variability of the K is influenced by various farming operations at different growing stages and the peculiarity of each crop. This work demonstrated that, the soil erodibility factor can be determined considering the crops and stages of development, in addition to geological attributes.

Climate Change and Land Use Change of Rural Households in The Red River Delta, Vietnam

2013 ◽  
pp. 79-94
Author(s):  
Ngoc Luu Bich
Keyword(s):  
Climate Change ◽  
Land Use ◽  
Agricultural Land ◽  
Rural Households ◽  
River Delta ◽  
Red River ◽  
Red River Delta ◽  
Sea Levels ◽  
Main Production ◽  
Farming Households

Climate change (CC) and its impacts on the socio-economy and the development of communities has become an issue causing very special concern. The rise in global temperatures, in sea levels, extreme weather phenomena, and salinization have occurred more and more and have directly influenced the livelihoods of rural households in the Red River Delta – one of the two regions projected to suffer strongly from climate change in Vietnam. For farming households in this region, the major and traditional livelihoods are based on main production materials as agricultural land, or aquacultural water surface Changes in the land use of rural households in the Red River Delta during recent times was influenced strongly by the Renovation policy in agriculture as well as the process of industrialization and modernization in the country. Climate change over the past 5 years (2005-2011) has started influencing household land use with the concrete manifestations being the reduction of the area cultivated and the changing of the purpose of land use.

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