Habitat use, population size, and nesting ecology of conservation priority bird species using restored fields in agricultural landscapes

birds;farmland;habitat restoration;private-land programs;use;conservation planning;habitat selection;fitness

Reiley, Bryan M.

关键词: birds;    farmland;    habitat restoration;    private-land programs;    use;    conservation planning;    habitat selection;    fitness;   

Others  :  https://www.ideals.illinois.edu/bitstream/handle/2142/99344/REILEY-DISSERTATION-2017.pdf?sequence=1&isAllowed=y

美国|英语

来源: The Illinois Digital Environment for Access to Learning and Scholarship

【 摘 要 】

Agricultural intensification has negatively affected biodiversity throughout the world. In the U.S., population declines of many early successional bird species have been linked with habitat loss due to agriculture. One conservation effort that attempts to mitigate these losses is through programs that restore habitat on private lands that were formerly used for row-crop agriculture (hereafter private land programs). These programs have been widely regarded as beneficial to wildlife at local, landscape, and regional scales. In particular, studies have shown that farmland restoration efforts are associated with population-level increases of some conservation priority bird species. However, most studies in these habitats have focused exclusively on grassland bird species and so information is lacking on the habitat use of species that occupy later successional habitat. Based on their scale, and the lack of alternative large-scale solutions, these programs likely present the best opportunity for achieving broad scale conservation goals for birds in Midwestern landscapes. Although we know these programs provide large-scale conservation benefits, we do not understand the magnitude of this contribution. Beyond habitat use and population goals, conservation efforts to attract birds are only effective if those birds successfully reproduce. Therefore, an understanding of the relationship between selected habitat features and fitness consequences are important to understanding the conservation benefit of restored habitats, especially in situations where these are more likely to be decoupled such as agriculturally fragmented landscapes.Specifically, my research focused on addressing: (1) What attributes of restored patches are associated with habitat use by conservation priority birds and how this habitat use is mediated by the surrounding landscape, particularly the prevalence of surrounding agriculture?, (2) Are current levels of farmland restoration enough to achieve population goals for declining species and, if not, what level of additional restoration would be needed to achieve them?, (3) Are the habitat selection patterns of birds in these agriculturally fragmented landscapes associated with successful reproduction, and do relationships between selection and fitness vary among spatial scales? Regarding my first question, response to habitat features at all scales varied by species but the amount of habitat restoration in the surrounding landscape generally had little influence on habitat use; in most cases the amount of surrounding agriculture did not moderate the effect of surrounding restored habitat. For question 2, I found that current restoration efforts in Illinois may be achieving population goals for the Bell’s Vireo and Willow Flycatcher, but more than 10 times the current amount of restored habitat would be required to achieve the population goal for the Field Sparrow and Northern Bobwhite. Lastly, analyses related to my third question demonstrated that nesting Bell’s Vireos and Willow Flycatchers selected habitat that increased nest survival, but not number of young fledged from successful nests, in these drastically altered landscapes. Patterns between nest survival and selected habitat features were apparent at the nest-site scale, but not at the patch or landscape scales. Overall, this study demonstrates the importance of private land programs to conservation priority birds, including what features are associated with their use and how to increase habitat selection by these species, that they are providing population level increases that achieve conservation goals for some species, and that, for two species, breeding habitat selection in agriculturally fragmented landscapes was not maladaptive.