Drivers of declines in common loon (Gavia immer) productivity in Ontario, Canada

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.

Download Full-text

Common Loon (Gavia immer)

10.2173/tbna.313.p ◽

1997 ◽

Author(s):

Judith W. McIntyre ◽

Jack F. Barr

Keyword(s):

Gavia Immer ◽

Common Loon

Download Full-text

Long term monitoring of the common loon (Gavia immer) population on 18 lakes in Kejimkujik National Park, Nova Scotia, Canada

SIL Proceedings 1922-2010 ◽

10.1080/03680770.2009.11902220 ◽

2009 ◽

Vol 30 (5) ◽

pp. 705-708

Author(s):

Joseph Kerekes ◽

Peter Hope ◽

Chris McCarthy ◽

Sally O'Grady

Keyword(s):

Nova Scotia ◽

National Park ◽

Gavia Immer ◽

Common Loon ◽

The Common ◽

Long Term Monitoring ◽

Kejimkujik National Park ◽

Term Monitoring

Download Full-text

Additional Data and Perspectives on Interspecific Aggression in the Common Loon, Gavia immer

The Canadian Field-Naturalist ◽

10.22621/cfn.v125i1.1127 ◽

2011 ◽

Vol 125 (1) ◽

pp. 61

Author(s):

Martin L. Morton ◽

Maria E. Pereyra

Keyword(s):

Additional Data ◽

Gavia Immer ◽

Common Loon ◽

Interspecific Aggression ◽

Aythya Americana ◽

The Common

We witnessed the killing of a female Redhead (Aythya Americana) by a male Common Loon (Gavia immer). The wound was delivered into the abdomen from below, and death occurred because of a torn, hemorrhaging liver. This same Common Loon also threatened a female Ring-necked Duck (Aythya collaris) with ducklings. We hypothesize that interspecific aggression by loons might be energetically costly but is sometimes adaptive because it deters predators.

Download Full-text

Growth and Energy Requirements of Captive-Reared Common Loon (Gavia Immer) Chicks

The Auk ◽

10.1093/auk/124.4.1158 ◽

2007 ◽

Vol 124 (4) ◽

pp. 1158-1167

Author(s):

François Fournier ◽

William H. Karasov ◽

Kevin P. Kenow ◽

Michael W. Meyer

Keyword(s):

Growth Rate ◽

Body Mass ◽

Developmental Change ◽

Assimilation Efficiency ◽

Bird Species ◽

Metabolizable Energy ◽

Energy Requirements ◽

Growth Rate Constant ◽

Gavia Immer ◽

Common Loon

AbstractWe measured the energy requirements during postnatal development of six hand-reared Common Loon (Gavia immer) chicks using continuous feeding trials and doubly labeled water. At fledging, the mean (± SE) body mass of chicks was 3,246 ± 51 g. They reached asymptotic body mass in ≈66 days and had a mean growth rate constant of 0.089 ± 0.002 day−1, which was greater than growth rate constants of other, similar-sized precocial birds. Between hatch and day 66, chicks allocated 16.5% of their metabolizable energy to new tissue, lower than the average for other bird species (20%), which might be expected considering their precocial mode of development. There was a developmental change in the assimilation efficiency of food (metabolizable energy coefficient), with a mean of 0.64 ± 0.03 in chicks aged 21 days, rising to 0.83 ± 0.07 in chicks aged 35 days.Les besoins en énergie durant la croissance chez des jeunes Gavia immer élevés en captivité

Download Full-text