scholarly journals Changes in Loon (Gavia spp.) and Red-necked Grebe (Podiceps grisegena) Populations in the Lower Matanuska-Susitna Valley, Alaska

2004 ◽  
Vol 118 (2) ◽  
pp. 210
Author(s):  
Tamara K. Mills ◽  
Brad A. Andres
Keyword(s):  
Human Population ◽  
Gavia Immer ◽  
Common Loon ◽  
South Central ◽  
Proactive Management ◽  
Common Loons ◽  
Lakeshore Development ◽  
Wildlife Populations ◽  
Podiceps Grisegena ◽  
Northwest Region

More than two-thirds of the human population of Alaska resides in the south-central portion of the state, where its continued growth is likely to affect some wildlife populations negatively. To assess changes in waterbird populations in this region, we compared counts of Common Loons (Gavia immer), Pacific Loons (G. pacifica), and Red-necked Grebes (Podiceps grisegena) made on Matanuska-Susitina Valley lakes. In general, the number of lakes occupied by loon or grebe pairs decreased between 1987 and 1999. Decreases in the number of lakes occupied by Common Loons were less drastic in the northwest region of the study area than in the southeast region; human development is greater in the southeastern portion of our study area. Contrary to lake occupancy, the percentage of lakes that fledged Common Loon chicks remained stable between years. Because the human population is expected to continue to grow, proactive management of lake use and lakeshore development, coupled with monitoring of loon and grebe occupancy and productivity, is needed to ensure the persistence of these waterbird populations in the lower Matanuska-Susitna Valley.

The Effects of Lakeshore Development on Common Loon (Gavia immer) Productivity in the Adirondack Park, New York, USA

Waterbirds ◽  
2014 ◽  
Vol 37 (sp1) ◽  
pp. 94-101 ◽  
Author(s):  
Carolyn A. Spilman ◽  
Nina Schoch ◽  
William F. Porter ◽  
Michale J. Glennon
Keyword(s):  
New York ◽  
Adirondack Park ◽  
Gavia Immer ◽  
Common Loon ◽  
Lakeshore Development

scholarly journals Citizen Science Observations Reveal Long-Term Population Trends of Common and Pacific Loon in Urbanized Alaska

2019 ◽  
Vol 10 (1) ◽  
pp. 148-162 ◽  
Author(s):  
Laura A. McDuffie ◽  
Julie C. Hagelin ◽  
Marian L. Snively ◽  
Grey W. Pendleton ◽  
Audrey R. Taylor
Keyword(s):  
Citizen Science ◽  
Cost Effective ◽  
Sampling Bias ◽  
Gavia Immer ◽  
Lake Area ◽  
Common Loon ◽  
Chick Survival ◽  
Science Data ◽  
Common Loons

Abstract For more than 30 y, the Alaska Loon Watch (1985–1999) and the Alaska Loon and Grebe Watch (2000–2015) engaged citizen scientist participants to record more than 10,000 observations of common loons Gavia immer and Pacific loons Gavia pacifia at 346 lakes in five subregions of southcentral Alaska. We used generalized linear mixed models to estimate long-term trends in adult loon counts and chick survival and examined environmental variables associated with loon abundance. Adult common loon counts increased in all five subregions by 0.6–3.6% annually, whereas Pacific loons decreased 3% in the Anchorage subregion, but otherwise had trends not distinguishable from zero. Lake area was positively associated with common loon abundance and negatively associated with Pacific loon abundance. We also noted an inverse relationship between common loon and Pacific loon presence, consistent with the premise of interspecific competition. We did not find strong relationships between loon presence and predictor variables indicative of human disturbance or lakeshore development. Estimates of chick survival over time also revealed no clear pattern, although common loon chicks showed a decline in survival over the study period in one subregion. Citizen science programs provide agencies with a cost-effective tool to collect data over large spatial and temporal extents, which may not be feasible otherwise. However, there are ramifications of common data deficiencies associated with casual or unstructured observations, which can violate the assumptions required for rigorous statistical analysis. The implementation of a carefully predefined sampling protocol can avoid sampling bias, eliminate stringent assumptions, and ensure higher information content of citizen science data.

scholarly journals Size Characteristics of Stones Ingested by Common Loons

The Condor ◽  
2001 ◽  
Vol 103 (1) ◽  
pp. 189-191
Author(s):  
J. Christian Franson ◽  
Scott P. Hansen ◽  
Mark A. Pokras and ◽  
Rose Miconi
Keyword(s):  
United States ◽  
New England ◽  
Southeastern United States ◽  
The United States ◽  
Gavia Immer ◽  
Common Loon ◽  
Common Loons

Abstract Common Loon (Gavia immer) carcasses recovered in New England had more stones of greater combined mass in their stomachs than loons from the southeastern United States. Stones retained in sieves with mesh sizes between 4.75 and 8.00 mm accounted for the greatest percentage (by mass) of grit in loon stomachs. The median longest dimension of the largest single stone in each stomach was 12.5 mm in loons from New England and 10.7 mm in loons from the southeast (maximum = 23.1 mm and 16.8 mm, respectively). A recent national proposal to restrict the use of certain fishing weights in the United States called for a ban on lead fishing sinkers of 25.4 mm or less in any dimension. Our findings suggest it is unlikely that Common Loons would ingest lead fishing weights greater than 25.4 mm in any dimension, if such ingestion was solely the result of their search for replacement stones for their stomachs. However, this does not preclude the possibility that loons may ingest larger fishing weights under other circumstances, such as the consumption of fish with attached sinkers.

Common Loon (Gavia immer)

2020 ◽  
Author(s):  
David C. Evers ◽  
James D. Paruk ◽  
Judith W. McIntyre ◽  
Jack F. Barr
Keyword(s):  
Gavia Immer ◽  
Common Loon

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

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

Common Loon (Gavia immer)

1997 ◽  
Author(s):  
Judith W. McIntyre ◽  
Jack F. Barr
Keyword(s):  
Gavia Immer ◽  
Common Loon
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