Ashley Hansen, 2022

Thesis:

Use of an avian predator as a biological control agent in agricultural systems: Do barn owls (Tyto alba) impact rodent abundance in a vineyard setting?

Ashley studied how barn owls impact rodent populations within Napa Valley vineyards. Over the barn owl breeding season, she compared rodent populations and their activity in vineyards with and without barn owl boxes. She found that the presence of barn owl nest boxes significantly reduced gopher activity! Her research advanced our understanding of using barn owls as a method of pest control and helped establish that barn owls attracted to nest boxes in winegrape vineyards can meaningfully suppress the number of rodent pests. After graduating, Ash went on to work in the Alumni Office for Cal Poly Humboldt

Fatime Jomaa, 2025

Thesis:

The use of social information for prospecting and nest site selection by Western Bluebirds (Sialia mexicana)

Fatime will be examining methods that may accelerate songbird nest box occupancy in agricultural systems. She will investigate whether prospecting Western Bluebirds use social information to select nest sites in Napa Valley vineyards by broadcasting signals that simulate conspecific presence and reproductive success in newly deployed nest boxes. By manipulating cues indicative of ideal breeding habitat, their effects on nest site selection can be used to inform management strategies in vineyard systems that seek to attract these birds for the ecosystem services they may provide.

Amy Leist, 2007

Thesis:

The importance of fruit to Swainson’s thrushes, Catharus ustulatus, at stopover sites during fall migration: A field test of plasma metabolite analysis.

After Humboldt, Amy worked for the Great Basin Bird Observatory.

For her thesis, Amy used blood metabolite analysis to determine if migrating Swainson’s Thrushes selecting habitats rich in food were feeding more effectively than those selecting habitats with fewer fruits. The concentrations of triglycerides and beta-hydroxy butyrate in a bird’s blood can reveal whether that bird has been feeding rapidly, feeding slowly, or fasting in the previous 1-2 hours. Therefore, blood metabolites can be a useful tool to assess foraging habitat quality for migrating songbirds, which are difficult to track or recapture. Following Jim Tietz’s project (see below), Amy worked in and around the Lanphere Dunes unit of the Humboldt Bay National Wildlife Refuge.

Maddie Ybarra, 2024

Thesis:

The effects of native perennial cover on avian physiological indicators of habitat quality in California coastal prairie rangelands.

Maddie investigated the physiological responses to native perennial cover for two grassland bird species, Grasshopper Sparrow (Ammodramus savannarum)and Savannah Sparrow(Passerculus sandwichensis). Specifically, she used leukocytes (white blood cells) and body condition to assess whether a higher percentage of native perennials infers higher quality habitat. Previous research shows that rangeland practices such as range seeding and managed livestock grazing promote native perennial growth within grasslands, but further research needs to be completed to assess how habitat quality is affected for these grassland birds.Maddie worked on ranches in San Mateo County that are part of Point Blue Conservation Science’s Rangeland Monitoring Network to help quantify the effect of rangeland practices on grassland birds. After completed her MSc, Maddie went on to pursue a PhD at The Ohio State University.

Stephanie Eyes, 2014

Thesis:

The effects of fire severity on California spotted owl habitat use patterns

After Humboldt, Stephanie went on to work for US Forest Service.

For her thesis, Stephanie examined how fire severity affects patterns of California spotted owl (Strix occidentalis occidentalis) habitat use in Yosemite National Park. She used radio telemetry to monitor a population of spotted owls inhabiting recently burned forests (<15 years) to document nocturnal foraging locations. She conducted a habitat analysis to help determine owl response to a range of fire severities.

Sacha Heath, 2011

Thesis:

The effects of bird and bat arthropod predation on sapling black cottonwoods in the context of restoration

After Humboldt, Sacha went on to earn a PhD at University of California at Davis.

For her Humboldt thesis, Sacha thought about ways in which birds contribute to the restoration of their own breeding habitat. She approached one aspect of this broader question by investigating whether insectivorous birds indirectly affect black cottonwood sapling growth by reducing leaf damage via herbivorous insect consumption. She studied these interactions along three tributaries to Mono Lake, California where riparian breeding birds and the habitat on which they depend are recovering from decades of municipal water diversions.

Dabid Garcia,

Thesis:

Testing Vegetation Composition as a Predictor of Soil Organic Carbon on Working lands in California Using a Voluntary Monitoring Network

Dabid will be analyzing vegetation composition and soil core data collected from many ranches across California to look for correlations between plant species composition and soil organic carbon. On working lands, vegetation composition has the potential to alter the amount of carbon being introduced into the soil through a mix of physical and biological processes. Studies have shown that land management practices can greatly influence vegetation composition, thus shifting the soil ecology and chemistry. Loss of native plant populations in the state of California have been linked to a decline in total biodiversity in local ecosystems. By comparing soil carbon data to the above ground vegetation composition, Dabid aims to find possible correlations between native plant species abundance and the amount of soil carbon measured at each sampling site. This project will use data collected by Point Blue Conservation Science’s Rangeland Monitoring Network, a collaborative effort between biologists and private land managers to monitor working lands for soil health, vegetation composition, and bird species diversity. Findings from this study may be used to inform land management practices to preserve and promote the ecological health of rangeland ecosystems.

Elizabeth Meisman,

Thesis:

Testing Adaptive Flexibility in Breeding Swainson’s Hawk Territory Habitat Selection

Lizziwill be investigating potential mismatchesbetween habitat quality and selection in Swainson's Hawks (Buteo swainsoni) in Northern California. In long-lived territorial species like Swainson’s Hawks, these mismatches may pose serious risk to population viability. One of the longest running raptor studies in North America has continuously monitored breeding in a population of Swainson’s Hawks in Butte Valley, California since 1979, representing more than 40 years of research. Swainson’s Hawks exhibit strong site fidelity to territories on their breeding grounds. The majority of breeding pairs have established territories around, or in close proximity to, irrigated farmlands producing hay varieties (e.g., alfalfa). This long-term dataset is ideal to test whether adaptive habitat selection is operating as habitat conditions have changed over time. This research aims to explain the influence of varying agricultural crops to Swainson's Hawk territory selection and reproductive success in the Butte Valley over time. This information will have implications for the viability of the Butte Valley Swainson’s hawk population in the face of climate change and anticipated water shortages.

Jim Tietz, 2006

Thesis:

Stopover ecology and habitat selection in fall migrant Swainson’s Thrushes (Catharus ustulatus) along the northern California coast.

After Humboldt, Jim worked for PRBO Conservation Science.

For his thesis, Jim used using radio telemetry to track migrating thrushes in forested habitats of the Lanphere Dunes near Arcata. He tested whether the birds select vegetation primarily in response to habitat structure (shrub density) or food availability (mainly huckleberries).

Megan Milligan, 2014

Thesis:

Quantifying pest control services by birds in Kenyan coffee farms

After Humboldt, Megan went on to work as an ornithologist at Hastings Natural History Reservation and then on to earn a PhD at Montana State Unversity.

For her thesis at Humboldt, Megan studied avian predation in Kenyan coffee farms and examined how pest control is influenced by the local landscape and bird community. Her project aimed to answer the following questions: are birds providing pest control services? Does that service vary with distance to the nearest forest fragment or the farm's vegetation complexity? Megan's results help reveal what habitat characteristics optimize the provisioning of pest control services by birds and inform land managers about whether it is advantageous to encourage bird populations on coffee farms.