Open Access. Powered by Scholars. Published by Universities.®
- Discipline
Articles 1 - 4 of 4
Full-Text Articles in Life Sciences
Estimates Of Calf Survival And Factors Influencing Roosevelt Elk Mortality In Northwestern California, Erin Nigon
Estimates Of Calf Survival And Factors Influencing Roosevelt Elk Mortality In Northwestern California, Erin Nigon
Cal Poly Humboldt theses and projects
Survival of juvenile ungulates is known to be highly variable, yet it is fundamental to understanding the dynamics and trends of wildlife populations. Factors influencing calf survival are poorly understood in northwestern California where Roosevelt elk (Cervus canadensis roosevelti) are known to exist. The objectives of this study were 1) to estimate summer and annual survival rates and determine recruitment rates for Roosevelt elk calves in the area, 2) to evaluate differences in calf survival by examining the effects of individual and population level covariates on summer and annual calf survival, 3) to identify factors influencing the timing …
Density And Distribution Of Piscivorous Fishes In The Sacramento – San Joaquin Delta, Christopher M. Loomis
Density And Distribution Of Piscivorous Fishes In The Sacramento – San Joaquin Delta, Christopher M. Loomis
Cal Poly Humboldt theses and projects
Predatory fishes, including numerous introduced species, are common to the Sacramento – San Joaquin Delta, but abundance data for most species is insufficient to determine the Delta-wide distribution and ecological impacts of these species. Predatory fishes (e.g. Striped Bass, Largemouth Bass have long been suspected of contributing to the decline of native species, including salmonids, but data has been insufficient to investigate this hypothesis. In this study, I present a novel method to assess predator fish populations across the southern Delta using DIDSON acoustic cameras and analyze the environmental associations that form the landscape and fine-scale distribution of predatory fishes. …
Abundance, Growth, And Predation By Non-Native Brown Trout In The Trinity River, Ca, Justin S. Alvarez
Abundance, Growth, And Predation By Non-Native Brown Trout In The Trinity River, Ca, Justin S. Alvarez
Cal Poly Humboldt theses and projects
Brown Trout were introduced to the Trinity River in Northern California in the 1890’s. Since 1932, Brown Trout have sustained their population without additional stocking. Over the last 15 years, fisheries managers have been concerned that predation by piscivorous Brown Trout may impede efforts to restore native salmonids, in particular endangered Coho Salmon. I investigated predation by Brown Trout on native fish in the 64 km of the main stem Trinity River below Lewiston Dam. Using a bioenergetics approach parameterized with field measurements of Brown Trout abundance and growth, I estimated the amount of energy needed to sustain the 2015 …
An Experimental Test Of Response By Common Ravens To Nest Exclosures, Teresa R. King
An Experimental Test Of Response By Common Ravens To Nest Exclosures, Teresa R. King
Cal Poly Humboldt theses and projects
Common ravens (Corvus corax) are intelligent generalists and a principal predator affecting population recovery of several threatened and endangered species, including the threatened western snowy plover (Charadrius nivosus nivosus). In Humboldt County, raven predation is a primary cause of low nest survival. Nest exclosures, cages around eggs that preclude entry by predators but allow plovers access to incubate, are known to increase nest success. However, speculation exists that exclosures may attract predators. The aims of this study were to summarize corvid distribution on Clam Beach County Park and Little River State Beach, evaluate habitat features associated …