Life Sciences Commons^™

Consequences Of Recruitmentdecisions And Heterogeneity On Age-Specific Breeding Success In A Long-Lived Seabird, Lise M. Aubry, David N. Koons, Jean Yves Monnat, Emmanuelle Cam

Wildland Resources Faculty Publications

An individual’s age at first reproduction and investment in successive reproductive attempts are involved in mechanisms that can impede somatic repair, resulting in a decline in reproductive abilities with age (reproductive senescence). We used long-term data from the Black-legged Kittiwake, a long-lived seabird, to address the relationship between recruitment age, age-specific breeding success (BS), and reproductive senescence, while accounting for breeding experience and temporal variation in BS. We first detected late-life improvement in BS across all recruitment groups, which we recognized as ‘‘within-generation selection’’ or the selective disappearance of ‘‘frail’’ phenotypes. When such heterogeneity was accurately accounted for, we showed …

Energy Budgets Of Eared Grebes On The Great Salt Lake And Implications For Harvest Of Brine Shrimp, Michael R. Conover, Joe N. Caudell

Wildland Resources Faculty Publications

About 1.5-million eared grebes (Podiceps nigricollis), representing half of the North American population, stage on Utah's Great Salt Lake, USA (GSL) during autumn migration to forage on brine shrimp (Artemia franciscana). Indirectly competing with birds for brine shrimp are commercial harvesters who annually collect >1 million kg (dry wt) of shrimp cysts (i.e., hardened eggs), an amount that during some years equals up to half of all brine shrimp cysts produced annually on the GSL. No information was available regarding what impact this commercial harvest was having on eared grebes. We determined daily energy requirements of eared grebes so that …

Concentrations Of Selenium And Mercury In Eared Grebes (Podiceps Nigricollis) From Utah’S Great Salt Lake, Usa, Michael R. Conover, Josh L. Vest

Wildland Resources Faculty Publications

We examined selenium and mercury concentrations in eared grebes (Podiceps nigricollis) that spent the fall of 2006 on the Great Salt Lake (UT, USA), where their diet consisted mainly of brine shrimp (Artemia franciscana). Selenium concentrations in livers varied based on when the grebes were collected (lower in September [mean ± standard error, 9.4 ± 0.7 μg/g dry wt] than in November [14.5 ± 1.4 μg/g]), on where the birds were collected on the Great Salt Lake (Antelope Island, 8.6 ± 0.5 μg/g; Stansbury Island, 15.2 ± 1.4 μg/g), and on the grebe's age (juveniles, 8.5 ± 1.5 μg/g; adults, …

Do Sharp-Tailed Grouse Select Loafing Sites To Avoid Visual Or Olfactory Predators?, Michael R. Conover, Jennifer S. Borgo

Wildland Resources Faculty Publications

Grouse should seek loafing sites hidden from predators; however, good hiding sites from predators that use vision to locate prey differ from good hiding sites from predators that use odor to locate prey. We compared characteristics of control sites to sites used for loafing by sharp-tailed grouse (Tympanuchus phasianellus) to determine whether selection of loafing sites was more influenced by the need to hide from visual or olfactory predators. Sites used for loafing were similar to control sites in characteristics that would help hide a grouse from visual predators (i.e., visual obstruction, lateral visibility, visual obstruction, cover ht, and surface …

Selenium And Mercury Concentrations In California Gulls Breeding On The Great Salt Lake, Utah, Usa, Michael R. Conover, Josh L. Vest

Wildland Resources Faculty Publications

We examined selenium (Se) and mercury (Hg) concentrations in adult California gulls (Larus californicus) nesting on the Great Salt Lake, Utah, USA, during 2006 and 2007. During 2006, the mean Se concentration (± standard error) was 18.1 ± 1.5 μg/g in blood on a dry-weight basis and 8.1 ± 0.4 μg/g in liver. During 2007, Se concentrations were 15.7 ± 1.5 μg/g in blood and 8.3 ± 0.4 μg/g in liver; Hg concentrations were 2.4 ± 0.3 μg/g in blood and 4.1 ± 0.5 μg/g in liver. Gulls collected from a freshwater colony located within the watershed of the Great …

Gang Brooding In Canada Geese: Role Of Parental Condition And Experience, Michael R. Conover

Wildland Resources Faculty Publications

Some Canada Geese (Branta canadensis) raise their broods by themselves (two-parent families), while others raise them in gang broods, defined as two or more broods amalgamated into a single cohesive unit and shepherded by four or more parents. From 1984 to 2005, I individually marked Canada Geese in New Haven County, Connecticut, so that I could compare the characteristics of adults that raise their goslings in gang broods to those of adults that raised their goslings in two-parent families. I wanted to determine if a parent's decision to form a gang brood was influenced by its age or body mass, …

Direct And Indirect Effects Of Climate Change On A Prairie Plant Community, Peter B. Adler, James Leiker, Jonathan M. Levine

Wildland Resources Faculty Publications

Background

Climate change directly affects species by altering their physical environment and indirectly affects species by altering interspecific interactions such as predation and competition. Recent studies have shown that the indirect effects of climate change may amplify or counteract the direct effects. However, little is known about the the relative strength of direct and indirect effects or their potential to impact population persistence.

Methodology/Principal Findings

We studied the effects of altered precipitation and interspecific interactions on the low-density tiller growth rates and biomass production of three perennial grass species in a Kansas, USA mixed prairie. We transplanted plugs of each …

Aspen Succession And Nitrogen Loading: A Case For Epiphytic Lichens As Bioindicators In The Rocky Mountains, Usa, Paul C. Rogers, Kori D. Moore, Ronald J. Ryel

Wildland Resources Faculty Publications

Question: Can lichen communities be used to assess shortand long-term factors affecting seral quaking aspen (Populus tremuloides) communities at the landscape scale? Location: Bear River Range, within the Rocky Mountains, in northern Utah and southern Idaho, USA. Method: Forty-seven randomly selected mid-elevation aspen stands were sampled for lichens and stand conditions. Plots were characterized according to tree species cover, basal area, stand age, bole scarring, tree damage, and presence of lichen species. We also recorded ammonia emissions with passive sensors at 25 urban and agricultural sites throughout an adjacent populated valley upwind of the forest stands. Nonmetric multidimensional scaling (NMS) …