scholarly journals Nocturnal Behavior of the Common Loon, Gavia immer

2008 ◽  
Vol 122 (1) ◽  
pp. 70 ◽  
Author(s):  
James D. Paruk
Keyword(s):  
Night Vision ◽  
Energy Budgets ◽  
Single Pair ◽  
Gavia Immer ◽  
Complete Understanding ◽  
Large Lakes ◽  
Common Loons ◽  
Nocturnal Behavior ◽  
Daily Energy ◽  
The Common

Very little is known about nocturnal activity of Common Loons (Gavia immer). Knowledge of both diurnal and nocturnal behavior is needed to gain a complete understanding of their ecology. I used night vision light intensifiers to observe nocturnal behaviors of Common Loons. Results were consistent with the hypothesis that, as visual predators, loons would not forage at night and also that they would spend the majority of their time resting (92%). Loons, however, were just as active locomoting (patrolling) during the night as they were during the day. This suggests daily energy budgets need to be reexamined to incorporate this overlooked aspect of loon behavior. Lastly, loons on large lakes with multiple loon territories spent more time locomoting than loons on lakes that had just a single pair.

Diving schedules of Common Loons in varying environments

2002 ◽  
Vol 80 (9) ◽  
pp. 1643-1648 ◽  
Author(s):  
Joseph J Nocera ◽  
Neil M Burgess
Keyword(s):  
Environmental Variation ◽  
Dive Duration ◽  
Diving Behaviour ◽  
Fish Abundance ◽  
Gavia Immer ◽  
Lake Chemistry ◽  
Common Loons ◽  
The Common ◽  
Varying Environments ◽  
External Stimuli

Many species of diving birds adjust their foraging behaviour in response to variation in their environment. The Common Loon (Gavia immer) is a visually oriented predator sensitive to environmental variation, yet little is known about the flexibility of its diving behaviour. We tested the hypothesis that loons adjust their diving schedules by increasing or decreasing the dive duration during foraging bouts to accommodate environmental variation during the breeding season. The dive duration and dive-pause components of the loon dive cycle did not vary among lakes with different lake chemistry, lake morphometry, mercury levels in their blood, or fish abundance. We observed some variation among loons in different stages of breeding in mean dive-pause intervals. The dive-pause component of the diving cycle of Common Loons does not seem to be related to the amount of time spent underwater. To our knowledge, this is the first report of such a nonlinear relationship in diving birds. We propose that loons vary the components of their diving behaviour independently and seem to alter their diving time budgets regardless of the external stimuli we addressed. This unresponsive diving schedule may make loons susceptible to catastrophic changes in prey densities within their foraging areas, as they are obliged to forage on one, or very few, lakes. Conversely, loons may only forage in lakes with fish abundance above a certain minimum threshold and preferentially avoid lakes with reduced prey abundance.

scholarly journals Common Loon, Gavia immer, Breeding Success in Relation to Lake pH and Lake Size Over 25 Years

2009 ◽  
Vol 123 (2) ◽  
pp. 146 ◽  
Author(s):  
Robert Alvo
Keyword(s):  
Breeding Success ◽  
Low Ph ◽  
Single Pair ◽  
Gavia Immer ◽  
Common Loon ◽  
Sulphur Deposition ◽  
Acidic Lakes ◽  
Ph Range ◽  
Lake Size ◽  
Critical Ph

I monitored Common Loon (Gavia immer) breeding success in relation to lake pH (range 4.0–8.5) between 1982 and 2007 on 38 single-pair lakes (5–88 ha) in the Sudbury, Ontario, area. No chicks fledged on lakes with pH < 4.4. Chicks fledged on lakes with slightly higher pH only if the lakes were relatively large. Acidic lakes became less acidic as sulphur dioxide emissions from the Sudbury smelters and sulphur deposition from other long-range sources decreased. Two lakes initially too acidic to support successful loon reproduction eventually had successful reproduction. One loon pair used two large acidic lakes (combined area 140 ha) connected by shallow rapids, and one of the adults made extremely long dives (average = 99 s) while foraging for the chicks. One chick died on that lake after apparently ingesting a very large food item; the lack of smaller items was attributed to the lake’s acidity. My results suggest that a shortage of food for chicks is the main reason why low pH reduces breeding success. I suggest that, for lakes without high levels of dissolved organic carbon (DOC), the critical pH for loon breeding success is approximately 4.3, and the suboptimal pH is approximately 4.4–6.0.

AN OUTBREAK OF TYPE E BOTULISM AMONG COMMON LOONS (GAVIA IMMER) IN MICHIGAN'S UPPER PENINSULA

1988 ◽  
Vol 24 (3) ◽  
pp. 471-476 ◽  
Author(s):  
Christopher J. Brand ◽  
Stephen M. Schmitt ◽  
Ruth M. Duncan ◽  
Thomas M. Cooley
Keyword(s):  
Gavia Immer ◽  
Upper Peninsula ◽  
Common Loons

Relative Reactivity Trends OP High Temperature Superconductor Phases

1992 ◽  
Vol 275 ◽  
Author(s):  
David R. Riley ◽  
Ji-Ping Zhou ◽  
A. Manthiram ◽  
John T. McDevitt
Keyword(s):  
Electron Microscopy ◽  
Carbon Dioxide ◽  
High Temperature ◽  
High Temperature Superconductor ◽  
Relative Reactivity ◽  
Complete Understanding ◽  
High Tc ◽  
X Ray ◽  
The Common ◽  
Scanning Electron

ABSTRACTMany of the high temperature superconductor phases degrade rapidly when in the presence of water, acids, carbon dioxide or carbon monoxide. In order to foster more rapid developments in the area of high-Tc research, it will be necessary to acquire a more complete understanding of the surface chemistry of these superconducting materials. In this paper, the relative reactivity of the common cuprate phases toward water is reported. X-ray powder diffraction and scanning electron microscopy measurements are utilized here to establish the reactivity trends.

Loon abundance and behaviour over four decades at a remote ecological reserve on Haida Gwaii, British Columbia, Canada

2021 ◽  
Vol 135 (1) ◽  
pp. 28-38
Author(s):  
Thomas Reimchen ◽  
Sheila Douglas
Keyword(s):  
British Columbia ◽  
Gasterosteus Aculeatus ◽  
Evolutionary Ecology ◽  
Inverse Correlation ◽  
Gavia Immer ◽  
Haida Gwaii ◽  
Average Wind Speed ◽  
The North ◽  
Common Loons ◽  
Ecological Reserve

Early studies (1976–1982) of the Drizzle Lake Ecological Reserve on Haida Gwaii, British Columbia focussed on the endemic Giant Threespine Stickleback (Gasterosteus aculeatus) and their predators. These surveys showed daily visits to the small lake (110 ha) by up to 59 adult non-breeding Common Loon (Gavia immer), an important stickleback predator and up to 19 breeding and non-breeding adult Red-throated Loon (Gavia stellata), which leave daily to forage in nearby marine waters. We continued loon surveys for 17 additional years (1983–1989, 2011–2020) and found that aggregations of non-breeding Common Loons occurred annually on the lake during July with maximum daily numbers of 78–83 individuals in 1987, 2018, and 2020 and a large increase from 2011 to 2020. We did not detect any relationship of these differences with the Pacific Decadal Oscillation but a significant inverse correlation with average wind speed. Average yearly numbers of Red-throated Loons declined by 50% from 1976 to 1989 and have remained low, with lowest numbers (<2) occurring in 2017. Two Red-throated Loon nesting territories on the lake were occupied from 1976 to 1995, with chicks occurring in 24 of 36 nests, but no successful nesting was observed on the lake over the last decade. The relative decline of Red-throated Loon in this reserve is similar to that reported in Arctic and Subarctic surveys of the species in the north Pacific and northern Europe. We discuss the implications for the evolutionary ecology of the sticklebacks and the conservation of the ecological reserve.

The breeding success of common loons (Gavia immer) in relation to alkalinity and other lake characteristics in Ontario

1988 ◽  
Vol 66 (3) ◽  
pp. 746-752 ◽  
Author(s):  
Robert Alvo ◽  
David J. T. Hussell ◽  
Michael Berrill
Keyword(s):  
Breeding Success ◽  
Benthic Algae ◽  
Gavia Immer ◽  
Acidic Lake ◽  
Acidic Lakes ◽  
Common Loons ◽  
Breeding Attempt ◽  
High Alkalinity ◽  
Highly Correlated ◽  
High Level

We examined the breeding success of common loons (Gavia immer) and made observations of loons feeding their young on small lakes (5.3–75 ha) with different alkalinities (−73 to 1804 μequiv./L) near Sudbury, Ontario. Alkalinity, pH, and conductivity were highly correlated with each other. There was a significant positive relationship between successful breeding and alkalinity on 68 lakes surveyed in 1982. Discriminant analysis showed that alkalinity, area, and colour of the lake contributed significantly to discrimination among lakes with successful, unsuccessful, and no breeding attempts. Lack of a breeding attempt tended to be associated with small, brown, low-alkalinity lakes, and successful breeding with large, clear, high-alkalinity lakes. For lakes with breeding attempts in 1982–1984, alkalinity (all years), depth (1983), and area (1984) provided significant discrimination between unsuccessful lakes and those on which young were raised. Unsuccessful breeding resulted primarily from brood mortalities on acidic lakes. Adult loons were more successful at securing fish on high-alkalinity lakes than on low-alkalinity lakes, and this may reflect differences in fish densities. A pair of loons attempting to raise a chick on a fishless, acidic lake fed the chick benthic algae and possibly benthic invertebrates, but flew to other lakes to feed themselves. We suggest that the high level of brood mortalities on acidic lakes resulted from a shortage of suitable food for the young.

Juvenile survival in common loons Gavia immer: effects of natal lake size and pH

2012 ◽  
Vol 43 (3) ◽  
pp. 280-288 ◽  
Author(s):  
Walter H. Piper ◽  
Jason S. Grear ◽  
Michael W. Meyer
Keyword(s):  
Juvenile Survival ◽  
Gavia Immer ◽  
Common Loons ◽  
Lake Size

Flexible energetics of cheetah hunting strategies provide resistance against kleptoparasitism

Science ◽  
2014 ◽  
Vol 346 (6205) ◽  
pp. 79-81 ◽  
Author(s):  
David M. Scantlebury ◽  
Michael G. L. Mills ◽  
Rory P. Wilson ◽  
John W. Wilson ◽  
Margaret E. J. Mills ◽  
...  
Keyword(s):  
Population Viability ◽  
Energy Budgets ◽  
Hunting Strategies ◽  
Direct Competition ◽  
Daily Energy ◽  
Balancing Energy ◽  
Individual Survival ◽  
Power Outputs ◽  
Wild Dogs ◽  
Increased Activity

Population viability is driven by individual survival, which in turn depends on individuals balancing energy budgets. As carnivores may function close to maximum sustained power outputs, decreased food availability or increased activity may render some populations energetically vulnerable. Prey theft may compromise energetic budgets of mesopredators, such as cheetahs and wild dogs, which are susceptible to competition from larger carnivores. We show that daily energy expenditure (DEE) of cheetahs was similar to size-based predictions and positively related to distance traveled. Theft at 25% only requires cheetahs to hunt for an extra 1.1 hour per day, increasing DEE by just 12%. Therefore, not all mesopredators are energetically constrained by direct competition. Other factors that increase DEE, such as those that increase travel, may be more important for population viability.

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