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

Journal of Raptor Research ◽

10.3356/jrr-21-14 ◽

2021 ◽

Author(s):

Charles J. Henny ◽

James L. Kaiser

Keyword(s):

Brood Reduction ◽

Haliaeetus Leucocephalus ◽

Bald Eagles ◽

Active Nest ◽

Rainbow Trout Oncorhynchus Mykiss ◽

Rotenone Treatment ◽

Negative Effect ◽

Feeding Program ◽

Information Number ◽

Reproductive Rates

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.

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Reproductive success of bald eagles (Haliaeetus leucocephalus) and its association with habitat or landscape features and weather in southeast Alaska

Canadian Journal of Zoology ◽

10.1139/z97-786 ◽

1997 ◽

Vol 75 (10) ◽

pp. 1595-1604 ◽

Cited By ~ 16

Author(s):

Scott M. Gende ◽

Mary F. Wilson ◽

Mike Jacobsen

Keyword(s):

Early Spring ◽

Average Density ◽

Nesting Success ◽

Egg Laying ◽

Haliaeetus Leucocephalus ◽

Bald Eagles ◽

Active Nest ◽

Southeast Alaska ◽

Landscape Features

Long-term data have been collected on nesting bald eagles (Haliaeetus leucocephalus) in three areas of southeast Alaska. The average density of active nests was among the highest recorded, but nest productivity (average number of young fledged per active nest) and success (percentage of active nests that fledged at least one young) were similar to values in other areas. Using logistic regression, nest productivity was associated with several habitat or landscape features (productivity was highest in proximity to spawning herring and at a particular location), each of which could be related to the availability of prey (fish) in the early spring (April, May) during egg laying and incubation. Consistency of nesting success was associated with the presence of tidal flats at one study site. Nest use, but not nesting success, was related to nesting success the previous year. Multiple regression showed that fewer nests per kilometre were successful in years with a high frequency of spring rains.

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Effects of Nesting Bald Eagles (Haliaeetus leucocephalus) on Behaviour and Reproductive Rates in a Great Blue Heron (Ardea herodias) Colony in Ontario

The Canadian Field-Naturalist ◽

10.22621/cfn.v131i4.1848 ◽

2018 ◽

Vol 131 (4) ◽

pp. 369-371

Author(s):

Bill Thompson

Keyword(s):

Single Species ◽

Mortality Rates ◽

Haliaeetus Leucocephalus ◽

Bald Eagles ◽

Fish Prey ◽

Movement Rates ◽

Ardea Herodias ◽

Great Blue Heron ◽

Significant Difference ◽

Reproductive Rates

Bald Eagles (Haliaeetus leucocephalus) and Great Blue Herons (Ardea herodias) are known to occasionally nest in mixed colonies, even though the former is one of the primary predators of the latter. I observed the two species in four heron colonies near Lake Simcoe, Ontario during two field seasons to assess whether rates of heron chick mortality or nest abandonment were greater in a colony that supported a nesting pair of Bald Eagles than in three nearby single-species colonies. I assessed the effects of eagle presence on heron behaviour using heron movement rates, the number of heron sentries left in colonies during the nesting period, heron nest mortality rates, and the average number of successfully fledged herons per nest. There was no statistically significant difference in movement rate among the four colonies, proportion of birds remaining as sentries, nor nest mortality rates. However, nests in the mixed colony successfully fledged significantly more heron young per nest than did nests in the single-species colonies. The mixed colony was located in a wetland and open lake system that provided extensive foraging habitat and an abundance of the preferred fish prey species of both Great Blue Herons and Bald Eagles, thus reducing predation pressure on the herons.

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Ecological interactions and habitat modification in nesting Common Murres, Uria aalge

Bird Conservation International ◽

10.1017/s0959270900003154 ◽

1996 ◽

Vol 6 (3) ◽

pp. 261-269 ◽

Cited By ~ 8

Author(s):

Julia K. Parrish ◽

Robert T. Paine

Keyword(s):

Reproductive Output ◽

Habitat Modification ◽

Haliaeetus Leucocephalus ◽

Uria Aalge ◽

Ecological Interactions ◽

Bald Eagles ◽

Predator Removal ◽

Common Murre ◽

Corvus Caurinus ◽

Common Murres

SummarySeabird populations suffer from a variety of natural and human-induced sources of mortality and loss of lifetime reproductive output. On the outer coast of Washington State, Common Murre Uria aalge populations have been in decline for approximately the last decade and are currently reproductively active only at Tatoosh Island. These murres nest in two basic habitat types: crevices (25% of the population) and larger cliff-top subcolonies (75%). Murres in cliff-top subcolonies have suffered dramatic reductions in reproductive success in recent years relative to conspecifics nesting in the crevices, primarily due to egg predation by Glaucous-winged Gulls Larus glaucescens and Northwestern Crows Corvus caurinus, facilitated by the presence of Bald Eagles Haliaeetus leucocephalus. Because predator removal is not feasible and creation of additional crevice habitat is difficult, expensive and potentially ineffective, we have designed a temporary habitat modification (the “silk forest”) which replaces the natural vegetation cover and modifies the interaction between murres and eagles. Within the test subcolony, murres nesting under and immediately adjacent to the silk forest produced nearly twice as many eggs per square metre as their conspecifics nesting in adjacent exposed-ground areas.

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Pharmacokinetics of a Single Intramuscular Injection of Ceftiofur Crystalline Free Acid in Bald Eagles (Haliaeetus leucocephalus)

Journal of Avian Medicine and Surgery ◽

10.1647/20-00038 ◽

2021 ◽

Vol 35 (3) ◽

Author(s):

Miranda J. Sadar ◽

Sherry K. Cox ◽

Abigail Duvall ◽

Michael P. Jones

Keyword(s):

Intramuscular Injection ◽

Free Acid ◽

Haliaeetus Leucocephalus ◽

Bald Eagles ◽

Single Intramuscular Injection

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Bald Eagle Lead Exposure in the Upper Midwest

Journal of Fish and Wildlife Management ◽

10.3996/032013-jfwm-029 ◽

2014 ◽

Vol 5 (2) ◽

pp. 208-216 ◽

Cited By ~ 19

Author(s):

Sarah E. Warner ◽

Edward E. Britton ◽

Drew N. Becker ◽

Michael J. Coffey

Keyword(s):

Lead Poisoning ◽

Lead Exposure ◽

Clinical Signs ◽

Local Environment ◽

Bald Eagle ◽

Haliaeetus Leucocephalus ◽

Upper Midwest ◽

Bald Eagles ◽

Potential Source ◽

Liver Lead Concentration

Abstract In 2012, we examined lead exposure in 58 bald eagles Haliaeetus leucocephalus found dead in Iowa, Minnesota, and Wisconsin. We determined lead concentrations in livers, examined differences in exposure among ages and between sexes, and recorded clinical signs consistent with lead poisoning. Most (60%) of the bald eagles had detectable lead concentrations, and 38% of the 58 had concentrations within the lethal range for lead poisoning. We found no differences in exposure based on sex or age, but we did find an inverse relationship between body and liver mass and liver lead concentration. The high percentage of lead-exposed bald eagles encouraged us to further examine potential sources of lead in our local environment. We initiated a study on the Fish and Wildlife Service's Upper Mississippi River National Wildlife and Fish Refuge to investigate if discarded offal piles from hunter-killed deer were a potential source of lead exposure to scavenging wildlife such as the bald eagle. Radiographs showed that 36% of offal piles in our sample area contained lead fragments ranging from 1 to 107 particles per pile. Our study indicated that 1) lead exposure rates for bald eagles found dead in our Upper Midwest study area were high, 2) more than one-third of the bald eagles found dead in Iowa, Minnesota, and Wisconsin had liver lead concentrations consistent with lead poisoning, and 3) discarded offal piles from deer shot with lead ammunition can be a potential source of lead exposure for bald eagles.

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Successful Renesting After Brood Loss by Southern Bald Eagles (Haliaeetus leucocephalus leucocephalus)

Journal of Raptor Research ◽

10.3356/jrr-17-67.1 ◽

2018 ◽

Vol 52 (4) ◽

pp. 528-529

Author(s):

Wojciech Krol

Keyword(s):

Haliaeetus Leucocephalus ◽

Bald Eagles

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Bald Eagles, Haliaeetus leucocephalus, Feeding on Spawning Plainfin Midshipman, Porichthys notatus, at Crescent Beach, British Columbia

The Canadian Field-Naturalist ◽

10.22621/cfn.v117i4.829 ◽

2003 ◽

Vol 117 (4) ◽

pp. 601 ◽

Cited By ~ 6

Author(s):

Kyle Hamish Elliott ◽

Christina L. Struik ◽

John E. Elliott

Keyword(s):

British Columbia ◽

Nous Avons ◽

Food Source ◽

Haliaeetus Leucocephalus ◽

Potential Importance ◽

Bald Eagles ◽

Porichthys Notatus ◽

Tide Height ◽

Consumption Rates ◽

Plainfin Midshipman

We observed Bald Eagles feeding on Plainfin Midshipman near Crescent Beach, British Columbia, in May and June 2001 and 2002. We quantified consumption rates and eagle numbers during this period, illustrating the potential importance of this food source to breeding eagles. Tide height was the only significant factor influencing consumption rates, likely because this variable reflected the availability of midshipman prey.Nous avons observé les Pygargues à tête blanche alimenter sur les Crapauds à nageoire unie près de Crescent Beach, Colombie-Britannique, en maie et juin 2001 et 2002. Nous avons mesuré les cadences de consommation et les nombres de pygargues pendant cette période, illustrant l’importance potentielle de cette source de nourriture pour les aigles. La taille de marée était le seul facteur significatif influençant les cadences de consommation et les nombres de pygargues pendant la période d’étude, probablement parce que cette variable a reflété la disponibilité des crapauds.

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Functions of perch relocations in a communal night roost of wintering bald eagles

Canadian Journal of Zoology ◽

10.1139/z00-015 ◽

2000 ◽

Vol 78 (5) ◽

pp. 809-816 ◽

Cited By ~ 10

Author(s):

Amy A Yackel Adams ◽

Susan K Skagen ◽

Richard L Knight

Keyword(s):

Cold Stress ◽

Social Dominance ◽

Haliaeetus Leucocephalus ◽

Foraging Success ◽

Bald Eagles ◽

Dominance Hierarchies ◽

Multiple Functions ◽

Descriptive Information ◽

Alternative Hypotheses ◽

Foraging Associations

We investigated the functions of perch relocations within a communal night roost of wintering bald eagles (Haliaeetus leucocephalus) along the Nooksack River, Washington, during two winters. We tested seven predictions of two nonexclusive hypotheses: (1) bald eagles relocate within roosts to assess foraging success of conspecifics and (2) bald eagles relocate to obtain thermoregulatory benefits from an improved microclimate. Additionally, we gathered descriptive information to allow refinement of further alternative hypotheses. We rejected the hypothesis that relocations are a means of assessing foraging success. Contrary to our expectations, immature eagles did not relocate to be closer to adults, and relocations were less frequent when food was less abundant. Our data support the hypothesis that eagles relocate within night roosts to obtain a favorable microclimate during winters when they are subjected to cold stress and food stress. In both winters, relocations were more frequent in the evening than in the morning. In both winters, most evening relocations were to the center of the roost rather than to its edge, and the frequency of relocation to the center was greater when temperatures were low. The microclimate hypothesis, however, explains only a limited number of relocations. Based on our findings, it is likely that relocation has multiple functions, including establishing and (or) maintaining foraging associations, establishing and (or) maintaining social-dominance hierarchies when food is less abundant, and nonsocial activities.

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