COLLABORATION IN A COMPLEX SOCIAL-ECOLOGICAL SYSTEM: MANAGEMENT OF MIGRATORY WATERFOWL ALONG THE PACIFIC FLYWAY
|Aviv Karasov-Olson; University of California Davis; email@example.com; Mark W. Schwartz, Mark N. Lubell
Management of migratory waterfowl operates at many different scales, spans a large geographic area, and involves a large set of actors and stakeholders. Coordination and collaboration are therefore required to ensure effective management across each species’ entire life cycle. Additionally, effective management of such a complex social-ecological system requires alignment between the social and ecological processes at play. Management of migratory waterfowl is, in many ways, designed to be collaborative and has been particularly successful relative to other species. I sought to identify evidence of social-ecological fit within waterfowl management and understand the extent to which success is attributed to collaboration. Using a qualitative study design, I conducted semi-structured interviews with 32 individuals working across the Pacific Flyway in different sectors and analyzed the interview transcripts using an inductive coding process. I found patterns in management goals and approaches that align with the ecological system across the flyway. Participants agreed that collaboration is critical to successful management, and that collaboration itself is a metric of success. This research has implications for understanding what leads to successful management of migratory species in general and may help identify opportunities for improved collaboration within the waterfowl community.
DABBLING IN DANGER: DUCKS OF THE TRIBE ANATINI DISPLAY INCREASED VIGILANCE IN RESPONSE TO PERCEIVED BALD EAGLE PREDATION PRESSURE IN THE SACRAMENTO VALLEY
|Kevin W. Dodd; CSU Chico; firstname.lastname@example.org; Dr. Don Miller, Dr. Kathy Gray, Dr. Mandy Banet, Laura Cockrell M.S.
|Predators can affect prey habitat use and behavior without direct interaction through the non-consumptive effects of predation, such as inducing fear. Fearful animals use vigilance, an anti-predator behavior, to reduce predation risk. However, there is a cost to vigilance. Time spent being vigilant for predators is time that is not spent foraging. This is known as the food-safety trade-off. This study used the predator-prey relationship between bald eagles (Haliaeetus leucocephalus) and ducks of the tribe Anatini in the Sacramento Valley of California to further explore the relationship between indirect predation and prey behavior. It is well documented that bald eagles feed on waterfowl. What is not known is the degree to which bald eagles indirectly affect waterfowl behavior and negatively impact fitness. This is especially important to understand as the Pacific Flyway waterfowl are threatened by habitat loss and climate change. I hypothesize that duck vigilance behavior is a function of perceived predation risk. As such, I predicted that as perceived bald eagle predation pressure increases, dabbling ducks would spend more time being vigilant, and less time on other behaviors, which may indicate a trade-off between avoiding predation and obtaining food. To test my hypothesis, time budgets of dabbling ducks at the Llano Seco Wildlife Refuge in the Sacramento Valley were collected and compared under varying levels of bald eagle predation pressure. Bald eagle surveys were conducted in the area around the study site and these time budgets were also analyzed over time as bald eagle numbers in the surrounding area fluctuated with fall and spring migrations. It was found that changes in the number of overwintering bald eagles in the area around Llano Seco between November and March did not influence duck vigilance behavior. However, as predicted, the sampled ducks did display more vigilance behavior when bald eagles were present at Llano Seco, compared to when they were not. Unexpectedly, duck vigilance behavior did not increase linearly with the number of bald eagles at the study site. Additionally, vigilance was greater when adult bald eagles were present, compared to when juveniles were present. Finally, the position of bald eagles in the environment (i.e., perching height and distance from the sampled ducks) had no effect on vigilance. The data did support the hypothesis that waterfowl behavior is a function of perceived predation risk, as evidenced by the increase in vigilance when bald eagles were present at the study site. However, this relationship did not hold up at a larger scale. The results lead to questions about how ducks detect potential threats, and how they respond. They also highlight the need to continue to monitor the relationship between bald eagles and waterfowl as we continue to face challenges associated with climate change.
COMMON RAVEN RESOURCE USE AND BEHAVIOR AROUND NESTING HABITAT OF THE THREATENED WESTERN SNOWY PLOVER
|Janelle Chojnacki; Cal Poly Humboldt; email@example.com; Dr. Barbara Clucas
Common ravens (Corvus corax) are intelligent, synanthropic predators subsidized by human activity throughout their range. Because of their attraction to human food resources, raven populations are increasing in North America, which has intensified predation risk for many protected species, including the federally threatened Western snowy plover (WSP, Charadrius nivosus nivosus). The breeding population of WSP in northwestern California has continued to fall below recovery goals and ongoing monitoring consistently reveals raven nest predation to be one of the most prominent direct causes of WSP reproductive failure. We are using GPS units to track the movement of ravens captured near WSP nesting beaches in coastal Humboldt County to better understand the factors influencing high raven abundance locally. Preliminary analysis of two years of data have revealed high variation in movement patterns, home range sizes, and apparent anthropogenic food resources based on breeding status and age of the individual, season, as well as surrounding landcover features. These findings, coupled with behavioral observations of ravens at beaches where WSP nest, indicate that raven management strategies such as hazing, egg oiling, or targeting human behavior would best be based on an understanding of raven behavior and surrounding land cover with a targeted site-specific approach.
PREY AVAILABILITY AT A VARIETY OF CALIFORNIA LEAST TERN (STERNULA ANTILLARUMBROWNI) COLONIES
|Amanda T Martinez; CSULB; firstname.lastname@example.org; Christine R. Whitcraft
The California least tern (CLT: Sternula antillarum browni) is an endangered seabird. Its phenology brings the CLT to the coast of California and Mexico each year to nest in colonies. An important factor believed to contribute to nesting success is prey availability; this study focuses on CLT foraging habits and prey availability at three colonies in southern California (2018-2020): Huntington Beach, Seal Beach, and Burris Basin. Foraging surveys were used to identify habitat use near each colony. Fish surveys were used to describe fish communities in areas where foraging had been observed. Community metrics from fish surveys were compared to guano and dropped fish to understand how food availability relates to CLT diet. CLT had higher use of open water habitats in close proximity to breeding grounds. Overall fish communities varied among habitat types and the combination of diet metrics suggested that CLT had access to high abundances of slender-bodied fish they were able to catch and consume. Suggesting prey availability did not limit the nesting success of the CLT, other factors may be influencing their population decline. Information from this study can help guide management of CLT colonies, provided a greater understanding of prey availability and diet of CLTs.
RIPARIAN AREA, NOT FRAGMENTATION, IS ASSOCIATED WITH BREEDING BIRD SPECIES RICHNESS IN THE GREAT BASIN, USA
|Frank A Fogarty; Cal Poly Humboldt; email@example.com; Jian Yen, Erica Fleishman, Rahel Sollmann, Alison Ke
The associations of habitat area and fragmentation with species richness long have been major topics within community ecology. Recent discussion has focused on properly assessing fragmentation independent of habitat area, and on whether fragmentation has significant negative or positive associations with species richness. We created a novel, multiple-region, N-mixture community model (MNCM) to examine the relations of riparian area and fragmentation with species richness of breeding birds in mountain ranges within the Great Basin, Nevada, USA. Our MNCM accounts for imperfect detection in count data at the survey-point level while allowing comparisons of species richness among regions in which those points are embedded. We used individual canyons within mountain ranges as regions in our model and measured riparian area and the normalized landscape shape index, a metric of fragmentation that is independent of total riparian area. We found that riparian area, but not its fragmentation, was a primary predictor of canyon-level species richness of both riparian obligates and all bird species. The relation between riparian area and riparian-obligate species richness was nonlinear: canyons with ~25 ha woody riparian vegetation had relatively high species richness, whereas species richness was considerably lower in canyons with <25 ha. Projections of future riparian contraction suggested that decreases in species richness are likely to be greatest in canyons that currently have moderate (~10-25 ha) amounts of riparian vegetation. Our results suggest that if a goal of management is to maximize the species richness of breeding birds in montane areas in the Great Basin, it may be more effective to focus on maximizing total riparian area rather than minimizing riparian fragmentation, and that canyons with at least moderate amounts of riparian vegetation should be prioritized.