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

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.

Recent switch by the Great Blue Heron Ardea herodias fannini in the Pacific northwest to associative nesting with Bald Eagles (Haliaeetus leucocephalus) to gain predator protection

2013 ◽  
Vol 91 (7) ◽  
pp. 489-495 ◽  
Author(s):  
I.M. Jones ◽  
R.W. Butler ◽  
R.C. Ydenberg
Keyword(s):  
Reproductive Success ◽  
Pacific Northwest ◽  
Close Association ◽  
Bald Eagle ◽  
Haliaeetus Leucocephalus ◽  
Bald Eagles ◽  
Safe Place ◽  
Ardea Herodias ◽  
Great Blue Heron ◽  
The Pacific

The Great Blue Heron Ardea herodias fannini Chapman, 1901 in the Pacific northwest appears to have modified nesting behaviour in response to the strong recent recovery of the Bald Eagle (Haliaeetus leucocephalus (L., 1766)) population. Previously undescribed, herons now often nest in close association with some breeding eagles, even though eagles depredate heron nestlings, are implicated in the recent reproductive decline of herons, and may induce abandonment of heron breeding colonies. We tested the hypothesis that breeding herons gain protection from the territorial behaviour of eagles. Natural observations and simulated incursions showed that nesting eagles actively repel other eagles within at least 250 m around the nest site, thereby establishing a relatively safe place for herons to nest. Surveys showed that 70% of heron nests and 19% of heron colonies were located within 200 m of eagle nests with high reproductive success. These herons had greater reproductive success than those nesting far from eagle nests.

Factors influencing the growth of Bald Eagles in north central Saskatchewan

1989 ◽  
Vol 67 (3) ◽  
pp. 606-611 ◽  
Author(s):  
Gary R. Bortolotti
Keyword(s):  
Hatching Asynchrony ◽  
Haliaeetus Leucocephalus ◽  
Relative Timing ◽  
Bald Eagles ◽  
Fish Prey ◽  
North Central ◽  
Factors Influencing ◽  
Lower Productivity ◽  
Absolute Growth ◽  
High Fish

Mass and eighth primary growth of nestling Bald Eagles (Haliaeetus leucocephalus) were studied in north central Saskatchewan from 1980 to 1982. There were no significant differences among years for any measure of growth. Clutch size and the relative timing of hatching within each breeding season also had no effect on growth. In broods of two young, second-hatched chicks (C2) grew slower than first-hatched chicks (C1) if the hatching interval between siblings was 2 days rather than 1 day. As both hatching asynchrony and the degree of suppressed growth of C2 were independent of absolute growth rates (and hence presumably food supply), it was unlikely that individual females modified the degree of asynchrony in any adaptive manner. Nestlings raised in an area predicted to have high fish (prey) productivity, given the morphology and chemistry of the lake, grew faster than chicks in an area of lower productivity. Growth rate was significantly correlated with the total mass of prey, but not the number of prey items, delivered to the nests by the parents.

scholarly journals Disapperance Rate of Bovine Fetuses at Grand Teton National Park, State Elk Feedgrounds and at the National Elk Refuge

1996 ◽  
Vol 20 ◽  
pp. 39-44
Author(s):  
Walter Cook ◽  
Elizabeth Williams ◽  
Shelli Dubay ◽  
E. Thorne
Keyword(s):  
National Park ◽  
Habitat Type ◽  
Analysis Of Covariance ◽  
Haliaeetus Leucocephalus ◽  
Bacterial Disease ◽  
Bald Eagles ◽  
Grand Teton National Park ◽  
Greater Yellowstone Area ◽  
Significant Difference ◽  
Bovine Fetuses

Brucellosis is a bacterial disease of cattle that has become established in elk and bison of the Greater Yellowstone Area. It causes elk and bison to abort and has the potential to be transmitted back to domestic cattle, which are now free of the disease. In this study we examined how long healthy bovine fetuses, as surrogates for aborted bison or elk fetuses, remained in the environment and could be available for contact by elk, bison, and cattle. Healthy bovine fetus carcasses were placed on state elk feedgrounds, the National Elk Refuge, and Grand Teton National Park to simulate an elk or bison aborted fetus. Fetuses were monitored until they disappeared due to scavenging. Fetuses took 26 hr on average to disappear from the National Elk Refuge, 46 hr at state elk feedgrounds, and 61 hr at Grand Teton National Park. Ninety percent of the fetuses could be expected to disappear from the National Elk Refuge within 60 hr (2.5 days); from state elk feedgrounds within 105 hr (4.4 days); and from Grand Teton National Park within 140 hr (5.8 days). Analysis of covariance showed that there was a significant difference in fetal disappearance rates depending on habitat type and site of placement. The dominant scavengers at all locations were coyotes (Canis latrans), but ravens (Corvus corax), magpies (Pica pica), bald eagles (Haliaeetus leucocephalus) and golden eagles (Aquila chrysaetos) also frequently participated in scavenging. We found that aborted fetuses could potentially serve as a source of bacterial infection for several days. This study will be expanded to include greater numbers in the coming season.

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

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.

Water-bird population changes in 1976–1990 on Besnard Lake, Saskatchewan: increases in loons, gulls, and pelicans

1993 ◽  
Vol 71 (8) ◽  
pp. 1681-1686 ◽  
Author(s):  
Jon M. Gerrard ◽  
Elston Dzus ◽  
Gary R. Bortolotti ◽  
P. Naomi Gerrard
Keyword(s):  
Present Report ◽  
Predatory Fish ◽  
Haliaeetus Leucocephalus ◽  
Small Fish ◽  
Gavia Immer ◽  
Bald Eagles ◽  
Herring Gulls ◽  
Ardea Herodias ◽  
Pelecanus Erythrorhynchos ◽  
Human Use

Declines in Common Loon (Gavia immer) populations associated with increasing human use of lakes have been reported from many areas of North America. In the present report we describe a lake in northern Saskatchewan, Besnard Lake, where there has been a substantial increase in the number of loons, from about 85 in 1976–1979 to about 165 in 1990. A comparison was made with numbers of other birds associated with water. Increases were also seen in American White Pelicans (Pelecanus erythrorhynchos), Osprey (Pandion haliaetus), Great Blue Herons (Ardea herodias), Herring Gulls (Larus argentatus), Ring-billed Gulls (L. delawarensis), and Bonaparte's Gulls (L. Philadelphia). No change was seen in mergansers (Mergus merganser and M. serrator), Bald Eagles (Haliaeetus leucocephalus), or Common Terns (Sterna hirundo). The period 1976–1990 has also seen increased human use on Besnard Lake. The reason for increased loon numbers is uncertain, but could possibly be related to an increase in the numbers of small fish in Besnard Lake as a result of increased fishing pressure disproportionately removing the larger, predatory fish.

Great Blue Heron (Ardea herodias)

2011 ◽  
Author(s):  
Ross G. Vennesland ◽  
Robert W. Butler
Keyword(s):  
Ardea Herodias ◽  
Great Blue Heron

INR Response to Low-Dose Vitamin K in Warfarin Patients

2021 ◽  
pp. 106002802199323
Author(s):  
Caitlin E. Kulig ◽  
A. Joshua Roberts ◽  
A. Shaun Rowe ◽  
Hahyoon Kim ◽  
William E. Dager
Keyword(s):  
Vitamin K ◽  
Primary Outcome ◽  
Low Dose ◽  
International Normalized Ratio ◽  
Mortality Rates ◽  
Observational Cohort Study ◽  
Significant Difference ◽  
Observational Cohort ◽  
Reduction Effect ◽  
Retrospective Observational Cohort Study

Background Literature suggests that 2 mg of vitamin K intravenously (IV) provides a similar effect as 10 mg to reverse warfarin. Doses <5 mg haven’t been studied in depth. Objective The objective was to determine the international normalized ratio (INR) reduction effect of ultra low-dose (ULD) IV vitamin K. Methods This retrospective, observational cohort study compared IV vitamin K doses of 0.25-0.5 mg (ULD) versus 1-2 mg (standard low dose [SLD]). The primary outcome assessed ΔINR at 36 hours; secondary outcomes assessed ΔINR at 12 hours and 30-day venous thromboembolism (VTE) and mortality rates. Results Of 88 patients identified (median baseline INR [IQR], 5.1 [3.1, 7.3] vs 4.5 [2.8, 8.2], ULD vs SLD, respectively), 59 had an INR at 12 hours. The ULD had fewer 12-hour INR values <2, with no statistical difference in the ΔINR at 12 hours between the ULD and SLD cohorts (median ΔINR, 2.2 [1.1, 3.4] vs 2.2 [1.1, 6.3]; P = 0.54; median INR, 2.3 vs 1.8). A total of 41 patients had both a 12- and 36-hour INR. No significant difference in the ΔINR between the 12- and 36-hour values occurred (median ΔINR, 0.52 [0.2, 0.91] vs ΔINR, 0.46 [0.18, 0.55]; P = 0.61), suggesting no rebound or excessive reversal and no difference in 30-day rates of VTE ( P > 0.99) or death ( P = 0.38). Conclusion and Relevance ULD IV vitamin K reversed INR similarly to doses of 1-2 mg without rebound. A ULD strategy may be considered in patients requiring more cautious reversal.

Impact of the period of the day on mortality and major cardiovascular complications after vascular surgeries

2020 ◽  
Vol 41 (Supplement_2) ◽  
Author(s):  
F.A.M Cardozo ◽  
T Artioli ◽  
B Caramelli ◽  
D Calderaro ◽  
P.C Yu ◽  
...  
Keyword(s):  
Multivariable Analysis ◽  
Total Mortality ◽  
Mortality Rates ◽  
Cardiovascular Complications ◽  
Cardiac Complications ◽  
Funding Source ◽  
Confounding Variables ◽  
Significant Difference ◽  
One Year ◽  
Night Period

Abstract Introduction Patients submitted to arterial vascular surgeries are at a high risk of postoperative cardiac and non-cardiac complications, therefore developing strategies to lower perioperative complications is essential to optimize outcomes for this subgroup. Recent studies have suggested that the period of the day in which surgeries are performed may influence postoperative major cardiovascular complications but there is still no evidence of this association in vascular surgeries. Purpose Our goal is to evaluate whether the period of the day in which surgeries are performed may influence mortality and cardiovascular outcomes in patients undergoing non-cardiac vascular procedures. Methods Patients who underwent non-cardiac vascular surgeries between 2012 and 2018 were prospectively included at our cohort. For this analysis, subjects were categorized into two groups: those who underwent surgery in the morning (7am - 12am) and those who underwent surgery in the afternoon/night (12:01pm - 6:59am). The primary endpoints were to compare the incidence of major adverse cardiac events (MACE - acute myocardial infarction, acute heart failure, arrhythmias, and cardiovascular death) and total mortality between morning and afternoon/night surgeries within 30 days and one year. The secondary endpoint was the incidence of perioperative myocardial injury (PMI) in both groups. PMI was defined as an absolute elevation of high-sensitivity cardiac troponin T (hs-cTnT) concentrations ≥14ng/L. Multivariable analysis using Cox proportional regression (with Hazard Ratio – HR and Confidence Interval – 95% CI) was performed to adjust for confounding variables, including emergency and urgent surgeries. Results Of 1267 patients included, 1002 (79.1%) underwent vascular surgery in the morning and 265 (20.9%) in the afternoon/night. After adjusting for confounding variables, the incidence of MACE at 30 days was higher among those who underwent surgery in the afternoon/night period (37.4% vs 20.4% – HR 1.43, 95% CI: 1.10–1.85; p=0.008). Mortality rates were also elevated in the afternoon/night group (21.5% vs 9.9%, HR 1.59, 95% CI: 1.10–2.29; p=0.013). After one-year of follow-up the worst outcomes persisted in patients operated in the afternoon/night: higher incidence of MACE (37.7% vs 21.2%, HR 1.37, 95% CI: 1.06–1.78; p=0.017) and mortality (35.8% vs 17.6%, HR 1.72, 95% CI 1.31–2.27; p&lt;0.001). There was no significant difference in the incidence of PMI between groups (p=0.8). Conclusions In this group of patients, being operated in the afternoon/night period was independently associated with increased mortality rates and incidence of MACE. Mortality and MACE at one year Funding Acknowledgement Type of funding source: Foundation. Main funding source(s): FAPESP - Fundação de Amparo a Pesquisa do Estado de São Paulo

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

1996 ◽  
Vol 6 (3) ◽  
pp. 261-269 ◽  
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.

Comparative demography of increasing and stable populations of blue grouse (Dendragapus obscurus)

1975 ◽  
Vol 53 (1) ◽  
pp. 1-11 ◽  
Author(s):  
J. A. Redfield
Keyword(s):  
Mortality Rates ◽  
Demographic Characteristics ◽  
Dendragapus Obscurus ◽  
Comparative Demography ◽  
Reproductive Rates ◽  
Stable Populations

The demographic characteristics of an increasing population of blue grouse were studied from 1968 to 1971. Increasing populations of grouse had high reproductive rates and slightly higher than average mortality rates among females as compared to stable populations.

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