Browsing by Subject "Nesting"

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    Investigating Bumble Bee Nesting Habitat Preferences and Natural History Along the Lower St. Croix River
    (Spring 2024) Dolan, Chan
    The upper midwestern US is one of the most changed landscapes on the planet, where much of the native vegetation has now been converted to agriculture. This loss of habitat has negative impacts on a variety of species, including bumble bees (Bombus). Minnesota alone is home to 25 species of bumble bees, with numerous species at risk of extinction that can partially be attributed to habitat loss. In order to implement effective conservation action for these important insects, identifying their habitat requirements is key. Generally, bumble bees require three main habitat components to complete their life cycle: foraging habitat, overwintering habitat, and nesting habitat. The majority of bumble bee research has focused on foraging habitat and flower preferences of bumble bees, leaving a large knowledge gap regarding nesting and overwintering habitat. However, these aspects of the bumble bee life cycle are notoriously difficult to observe and the time required to locate such locations is often considered prohibitive, leaving them to be relatively understudied. This lack of information on the nesting habitat requirements of bumble bees has negative consequences regarding conservation action, as habitat needs cannot be adequately identified and therefore may be inadequately protected. In this thesis, I investigate the nesting habitat preferences of wild bumble bees in different habitat types along the Lower St. Croix River Valley in the US states of Minnesota and Wisconsin. I used a novel, systematic approach to locating bumble bee nests directly in their habitat, spending equal effort in each habitat to quantify bumble bee nesting habitat preference. I also document various aspects of bumble bee nest natural history including nest activity, survival, and interactions with other species, which is important for informing future research directions regarding nesting bumble bee biology and ecology. The findings from this study also inform the development of standardized nest searching protocol for finding bumble bee nests more efficiently.
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    Survival and habitat use by post-fledging forest-nesting songbirds in managed mixed northern hardwood-coniferous forests.
    (2010-10) Streby, Henry M.
    Until recently, studies of breeding migratory songbirds have been primarily limited to the nesting season. Therefore, there is very little information about songbird survival and habitat use during the post-fledging period (i.e. the time between nesting and fall migration) available to those making management decisions. I expanded on the traditional nest-monitoring study and used radio telemetry to monitor survival and habitat use of fledgling songbirds in managed northern hardwood-coniferous forests of northern-Minnesota. In addition, I used mist-nets to sample use of early-successional forest stands (regenerating clearcuts) and forested wetlands by mature forest-nesting birds during the post-fledging period. I found that many assumptions of songbird nesting studies are unreliable, including the common assumption that the presence of a family group is confirmation of a successful nest in an occupied territory. In addition, I found that annual fledgling survival can vary considerably, and does not vary consistently with nest productivity, a finding with broad implications for models of songbird population growth. Furthermore, I found that habitat used by birds during the post-fledging period can be considerably different than that used for nesting, and that post-fledging habitat use can affect fledgling survival. In addition, I found that factors commonly affecting nest productivity (e.g. edge effects) can affect fledgling survival differently. From mist-netting, I found that many mature-forest birds used non-nesting cover types during the post-fledgling period, but most of that use was by only a few species, and hatch-year birds rarely used non-nesting cover types before independence from adult care. Models of capture rates in non-nesting cover types indicated that use of non-nesting cover types by mature-forest birds was primarily related to food availability and secondarily to cover in the form of relatively dense vegetation. My results indicated that nearly every conclusion made about breeding population ecology of mature-forest birds based only on nesting data was contradicted by data from the post-fledging period. My results clearly demonstrate that data from the entire breeding season (nesting and post-fledging) are necessary to understand songbird seasonal productivity and habitat associations.