Rotenone Use and Subsequent Prey Loss Lowers Osprey Fledging Rates Via Brood Reduction

ABSTRACT Fisheries managers used the fish toxicant rotenone to eradicate an undesirable brown bullhead (Ameiurus nebulosus) population and all other fish species at Hyatt Reservoir, Oregon, on 12 October 1989. This 4-yr study (1988–1990, 1992) compared effects of that rotenone project on Ospreys (Pandion haliaetus) nesting at Hyatt Reservoir and nearby Howard Prairie Reservoir (untreated reference)—the latter a reservoir where both brown bullheads and hatchery-released rainbow trout (Oncorhynchus mykiss) prospered. Because Hyatt Reservoir was treated after Osprey fall migration in 1989, the first 2 yr (1988 and 1989) yielded pretreatment information: number of Osprey pairs was unchanged and reproductive rates were similar and consistent at the two reservoirs. Yearling fish (200–250 mm) were restocked at Hyatt Reservoir in the spring of 1990 and Ospreys returned each year following rotenone treatment, with no decline in the number of occupied or active nests. The negative effect of the rotenone treatment on Ospreys was short-term, resulting in reduced reproductive rates (young/occupied nest, young/active nest, and young/successful nest) during the first nesting season posttreatment, although hatching rates were not affected. Osprey dive success and prey delivery rates declined sharply in 1990, leading to competition for food among siblings and brood reduction. Osprey reproductive rates and prey delivery rates at Hyatt Reservoir in both 1990 and 1992 remained below the extremely high pretreatment rates, but within the range required for population stability. Serious adverse effects of the fish loss on Osprey reproduction were minimized by: (1) the delay of the rotenone application until after breeding season, (2) the restocking of the treated reservoir in the following spring with some larger (yearling) fish (though the timing was late), (3) the maintenance of a supplemental feeding program for a nesting pair of Bald Eagles (Haliaeetus leucocephalus), which minimized kleptoparasitism on Ospreys, and perhaps most important (4) the presence of nearby water bodies, where Osprey obtained some fish in the 1990 and 1992 breeding seasons.

Ideal free eagles: Bald Eagle distribution in relation to salmon availability on four salmon spawning rivers

The movement of individuals according to the availability of resources has a fundamental effect on animal distributions. In the Pacific Northwest, Bald Eagles (Haliaeetus leucocephalus (Linneaus, 1766)) rely heavily on scavenging opportunities during the non-breeding period, and their distribution and movements are thought to be strongly influenced by the availability of post-spawning Pacific salmon (genus Oncorhynchus Suckley, 1861) carcasses. We surveyed the abundance of eagles and salmon on four adjacent rivers on Vancouver Island, British Columbia, Canada, during the 2017 fall spawning season. Salmon began to arrive in late September, peaked in abundance in mid-November, and were absent after early December. The seasonal progression of Bald Eagle abundance matched that of salmon carcass availability. The slope of proportional eagle – salmon relationship was significantly positive, though lower than the 1:1 match predicted by Ideal Free Distribution theory. The numerical response of Bald Eagles to salmon abundance was elevated on one of the rivers, potentially due to physical features such as sandbars and mudflats that increased the availability of carcasses and provided access points for eagles.

Anticoagulant rodenticide exposure and toxicosis in bald eagles (Haliaeetus leucocephalus) and golden eagles (Aquila chrysaetos) in the United States

Raptors, including eagles, are geographically widespread and sit atop the food chain, thereby serving an important role in maintaining ecosystem balance. After facing population declines associated with exposure to organochlorine insecticides such as dichlorodiphenyltrichloroethane (DDT), bald eagles (Haliaeetus leucocephalus) have recovered from the brink of extinction. However, both bald and golden eagles (Aquila chrysaetos) are exposed to a variety of other toxic compounds in the environment that could have population impacts. Few studies have focused on anticoagulant rodenticide (AR) exposure in eagles. Therefore, the purpose of this study was to determine the types of ARs that eagles are exposed to in the USA and better define the extent of toxicosis (i.e., fatal illness due to compound exposure). Diagnostic case records from bald and golden eagles submitted to the Southeastern Cooperative Wildlife Disease Study (University of Georgia) 2014 through 2018 were reviewed. Overall, 303 eagles were examined, and the livers from 116 bald eagles and 17 golden eagles were tested for ARs. The percentage of AR exposure (i.e., detectable levels but not associated with mortality) in eagles was high; ARs were detected in 109 (82%) eagles, including 96 (83%) bald eagles and 13 (77%) golden eagles. Anticoagulant rodenticide toxicosis was determined to be the cause of mortality in 12 (4%) of the 303 eagles examined, including 11 bald eagles and 1 golden eagle. Six different AR compounds were detected in these eagles, with brodifacoum and bromadiolone most frequently detected (81% and 25% of eagles tested, respectively). These results suggest that some ARs, most notably brodifacoum, are widespread in the environment and are commonly consumed by eagles. This highlights the need for research to understand the pathways of AR exposure in eagles, which may help inform policy and regulatory actions to mitigate AR exposure risk.

Hunting the eagle killer: A cyanobacterial neurotoxin causes vacuolar myelinopathy

Vacuolar myelinopathy is a fatal neurological disease that was initially discovered during a mysterious mass mortality of bald eagles in Arkansas in the United States. The cause of this wildlife disease has eluded scientists for decades while its occurrence has continued to spread throughout freshwater reservoirs in the southeastern United States. Recent studies have demonstrated that vacuolar myelinopathy is induced by consumption of the epiphytic cyanobacterial species Aetokthonos hydrillicola growing on aquatic vegetation, primarily the invasive Hydrilla verticillata. Here, we describe the identification, biosynthetic gene cluster, and biological activity of aetokthonotoxin, a pentabrominated biindole alkaloid that is produced by the cyanobacterium A. hydrillicola. We identify this cyanobacterial neurotoxin as the causal agent of vacuolar myelinopathy and discuss environmental factors—especially bromide availability—that promote toxin production.

An Automatic Blocking Keys Selection For Efficient Record Linkage

One of the important processes in the data quality field is record linkage (RL). RL (also known as entity resolution) is the process of detecting duplicates that refer to the same real-world entity in one or more datasets. The most critical step during the RL process is blocking, which reduces the quadratic complexity of the process by dividing the data into a set of blocks. By that way, matching is done only between the records in the same block. However, selecting the best blocking keys to divide the data is a hard task, and in most cases, it's done by a domain expert. In this paper, a novel unsupervised approach for an automatic blocking key selection is proposed. This approach is based on the recently proposed meta-heuristic bald eagles search (bes) optimization algorithm, where the problem is treated as a feature selection case. The obtained results from experiments on real-world datasets showed the efficiency of the proposition where the BES for feature selection outperformed existed approaches in the literature and returned the best blocking keys.

Assessment of a voluntary nonlead ammunition outreach program on midwestern national wildlife refuges

Lead exposure from spent hunting ammunition affects wildlife populations, human health, and poses challenges to natural resource management. In addition to existing data on this topic spanning [greater than] 100-years, data from the Upper Midwestern, United States (U.S.) demonstrated bald eagles have greater risk of lead poisoning by ingesting lead bullet fragments in gut piles and unretrieved carcasses related to deer hunting. In response, U.S. Fish and Wildlife Service (USFWS), Region 3 established an outreach program during 2016â€"2018 encouraging deer hunters to use nonlead ammunition while deer hunting on 54 National Wildlife Refuges (NWRs). This project used a mixed methods approach incorporating 12 structured observations of presentations given at four managed hunts, 29 semi-structured interviews of program staff, and an online survey of 325 NWR staff. Objectives were to (1) examine lead exposure risks and suggest communication strategies, (2) explore attitudes and experiences of NWR staff implementing the program, (3) examine staff attitudes about threats to bald eagles, lead poisoning in bald eagles, human health risks, use of nonlead hunting ammunition, and socio-economic ammunition factors, (4) examine factors influencing program support by staff, and (5) assess structured observations of nonlead presentations. Correspondingly, this research resulted in four manuscripts and an additional research note aligned with the objectives above. Five key findings were demonstrated by this research. First, the risk of lead exposure from spent hunting ammunition is a multi-dimensional complex issue affecting wildlife and human health with voluntary programs primarily addressing the issue. Although little used in the past, social science theory has the potential to provide a useful framework for evaluating voluntary nonlead ammunition programs. Second, semi-structured interviews of USFWS staff resulted in 12 broad themes organized around three categories: (1) challenges within the agency, (2) effects of contextual factors on program implementation, and (3) the effect of different elements observed to be present/absent in successful voluntary conservation programs. Third, an online survey showed differences in attitudes among staff who hunters and nonhunters, lead or nonlead ammunition use by hunters, and likely or unlikely future nonlead use by hunters. Fourth, the survey also demonstrated program support was greatest among refuge staff who strongly agreed with problems related to bald eagles and lead exposure, individuals who strongly agreed with the importance of informational program materials, and individuals with higher levels of innovation characteristics. Fifth, a descriptive assessment of presentations at managed deer hunts showed less than four minutes on average were spent discussing the issue with minimal hunter interest observed. Findings from this study provide suggestions for improving future nonlead outreach with additional staff training, audience segmentation with targeted messaging for different audiences, broadening the scope of outreach to include human health lead risks, and relevance of nonhunters as stakeholders. Methodologically, this study was the first application mixed methods to explore attitudes and behaviors of natural resource professionals implementing a nonlead outreach program using structured observations, semi-structured interviews, and an online survey. Bridging across multiple disciplines, this study developed a broader theoretical perspective for dealing with a complex socio-political landscape with a mixture of competing values, ethics, and worldviews among stakeholders. This study also showed the value of recognizing nonhunters as an important target audience, especially human health lead risks.