Responses to changes in prey availability by Common Murres and Thick-billed Murres at the Gannet Islands, Labrador

1999 ◽  
Vol 77 (8) ◽  
pp. 1278-1287 ◽  
Author(s):  
Rachel Bryant ◽  
Ian L Jones ◽  
J Mark Hipfner
Keyword(s):  
Breeding Success ◽  
Prey Availability ◽  
Feeding Rates ◽  
Chick Growth ◽  
Uria Lomvia ◽  
Foraging Effort ◽  
Common Murre ◽  
Common Murres ◽  
Capelin Mallotus Villosus ◽  
Adult Mass

We quantified Common Murre (Uria aalge) and Thick-billed (Uria lomvia) Murre chick diets, chick-feeding rates, breeding success, chick growth, adult masses, and pair members' time spent together at site at the Gannet Islands, Labrador, in 1996 and 1997, after a decline in capelin (Mallotus villosus) abundance along the coast of southern and central Labrador. These results, with the exception of time spent at the site, were compared with those collected by other researchers at the Gannet Islands in 1981-1983, before the capelin decline. The two species responded similarly to the decline. After the decline, murres fed their chicks up to 75% fewer capelin and up to 65% more daubed shannies (Lumpenus maculatus). Feeding rates of both murre species varied among years, without respect to changes in the proportion of capelin. We found no evidence for declines in colony attendance, breeding success, chick growth, and adult mass. No data on time spent at the site were available before the decline in capelin abundance, but after the decline, off-duty murres of both species spent a mean of 10 min at their sites per feeding visit. This amount of time was short with respect to that recorded for Common Murres elsewhere, suggesting that murres' foraging effort at the Gannet Islands was high and buffered the effects of prey availability on other parameters measured. Taken together, our results suggest that murres responded to changing capelin abundance by changing their chicks' diet, but were otherwise little affected.

Ecological relationships between Common Murres, Uria aalge, and Thick-billed Murres, Uria lomvia, at the Gannet Islands, Labrador. III. Feeding ecology of the young

1987 ◽  
Vol 65 (7) ◽  
pp. 1638-1649 ◽  
Author(s):  
T. R. Birkhead ◽  
D. N. Nettleship
Keyword(s):  
Caloric Intake ◽  
Interspecific Difference ◽  
Uria Aalge ◽  
Uria Lomvia ◽  
Ice Breakup ◽  
Common Murre ◽  
Interspecific Differences ◽  
Daubed Shanny ◽  
Common Murres ◽  
Capelin Mallotus Villosus

A simultaneous comparison of the foods of Common Murre, Uria aalge, and Thick-billed Murre, Uria lomvia, chicks at the same location showed that the species composition of fish fed to chicks of the two murre species differed significantly. In both years of the study, Common Murre chicks were fed predominantly capelin, Mallotus villosus (78–80% by weight), whereas Thick-billed Murre chicks were fed mainly daubed shanny, Lumpenus maculatus (61–70% by weight). Thick-billed Murres tended to feed their chicks more frequently than Common Murres, probably because in both years the mean caloric value of their prey was lower than that of the Common Murre's. No other statistically significant interspecific differences were consistent between years. Prey lengths and weights overlapped considerably between the murre species, and the caloric intake of chicks showed no consistent interspecific difference. Marked interyear differences in feeding rate, prey size, and caloric intake occurred in both species. In 1982 ice breakup was late, and the murres' breeding seasons were delayed; this appeared to result in poor synchronization between the temporal pattern of food availability and the timing of each species' chick-rearing period, and the caloric intakes of chicks of both species were lower in that year than in 1983.

Ecological relationships between Common Murres, Uria aalge, and Thick-billed Murres, Uria lomvia, at the Gannet Islands, Labrador. I. Morphometrics and timing of breeding

1987 ◽  
Vol 65 (7) ◽  
pp. 1621-1629 ◽  
Author(s):  
T. R. Birkhead ◽  
D. N. Nettleship
Keyword(s):  
Egg Laying ◽  
Laying Date ◽  
Uria Aalge ◽  
Uria Lomvia ◽  
Ecological Relationships ◽  
Ice Breakup ◽  
Common Murre ◽  
Common Murres ◽  
Adult Body Weight ◽  
One Year

Several aspects of the breeding biology of Common Murres (Uria aalge) and Thick-billed Murres (Uria lomvia) in 1981–1983, at the Gannet Islands, Labrador, are described. At this colony there were ca. 60 000 pairs of Common Murres, and 1400 pairs of Thick-billed Murres. Common Murres were slightly heavier and had significantly shorter wings, and longer, narrower bills than Thick-billed Murres. The timing of egg laying varied between years (late breeding in one year was associated with late ice breakup), but the median laying date of Common Murres was consistently earlier (by up to 10 days) than that of Thick-billed Murres. For both species median laying dates fell between mid and late June each year. Common Murre eggs were larger and relatively longer than Thick-billed Murre eggs, but in both species fresh egg weight was about 11% of adult body weight. Incubation periods were similar in each species (33 days), but chick-rearing periods were longer in Common Murres (24 days) than in Thick-billed Murres (21 days) in all years. Seasonal patterns of colony attendance were broadly similar in the two species each year, except that Common Murres showed a consistent increase in numbers between laying and chick departure, and tended to remain at the colony for less time after chicks had departed compared with Thick-billed Murres. All birds of both species left the colony by mid-September each year.

scholarly journals Thickness of Common Murre (Uria aalge) eggshells in Atlantic Canada

2014 ◽  
Vol 128 (1) ◽  
pp. 72 ◽  
Author(s):  
Donald W. Pirie-Hay ◽  
Alexander L. Bond
Keyword(s):  
Newfoundland And Labrador ◽  
Shell Thickness ◽  
Egg Size ◽  
Environmental Pollutants ◽  
Maternal Investment ◽  
Uria Aalge ◽  
Uria Lomvia ◽  
Common Murre ◽  
Common Murres ◽  
Nesting Material

Reported values for eggshell thickness in Common Murre (Uria aalge) are few, and even fewer since the decline in use of organochlorine pesticides and other environmental pollutants that caused significant thinning of shells. The eggshells of Common Murres and Thick-billed Murres (Uria lomvia) are among the thickest and heaviest, proportionately, of any bird and this represents a non-trivial maternal investment. We measured the length and breadth of Common Murre eggs collected from Machias Seal Island, New Brunswick, in 2006, and Gull Island, Newfoundland and Labrador, in 2012, and we measured the thickness of the eggshells. Shell thickness was not related to egg size or volume, and it varied in individual eggs. The shells of Common Murre eggs from Machias Seal Island (mean and standard deviation [SD] (0.767, SD 0.078 mm) and Gull Island (0.753, SD 0.057 mm) were significantly thicker than any previously reported value and among the thickest of all birds. Such thickness is likely a result of nesting on rock substrate with no nesting material and, perhaps, high breeding densities.

Molecular identification of a backcross between a female common murre × thick-billed murre hybrid and a male common murre

1993 ◽  
Vol 71 (7) ◽  
pp. 1474-1477 ◽  
Author(s):  
V. L. Friesen ◽  
R. T. Barrett ◽  
W. A. Montevecchi ◽  
W. S. Davidson
Keyword(s):  
Interspecific Hybrids ◽  
Population Survey ◽  
Morphological Characters ◽  
Genetic Constitution ◽  
Uria Lomvia ◽  
New Techniques ◽  
Reliable Identification ◽  
Common Murre ◽  
Mitochondrial Cytochrome B ◽  
Common Murres

Reports of interspecific hybrids that are based on morphological characters are often questioned, but new techniques in molecular genetics permit reliable identification of hybrids as well as sensitive detection of introgression. As part of a larger population survey, morphology, allozymes, and mitochondrial DNA were compared among 239 thick-billed murres (Uria lomvia) from five Atlantic colonies and 143 common murres (Uria aalge) from four Atlantic colonies. One murre possessed the morphology and electrophoretic profile of a common murre, and the mitochondrial cytochrome b genotype of a thick-billed murre. Its genetic constitution suggests that a female thick-billed murre bred with a male common murre, producing a daughter that subsequently bred with a male common murre.

Recent changes in the winter diet of murres (Uria spp.) in coastal Newfoundland waters

2000 ◽  
Vol 78 (3) ◽  
pp. 495-500 ◽  
Author(s):  
Sherrylynn Rowe ◽  
Ian L Jones ◽  
John W Chardine ◽  
Richard D Elliot ◽  
Brian G Veitch
Keyword(s):  
Marine Organisms ◽  
Frequency Of Occurrence ◽  
Boreogadus Saida ◽  
Sources Of Information ◽  
Uria Lomvia ◽  
Northwest Atlantic ◽  
Winter Diet ◽  
Ecological Changes ◽  
Common Murres ◽  
Capelin Mallotus Villosus

We investigated the winter diet of murres (Uria spp.) in coastal Newfoundland waters in relation to environmental and ecological changes that have occurred in the Northwest Atlantic since the 1980s. We analyzed the contents of 371 stomachs (311 from Thick-billed Murres, Uria lomvia, and 60 from Common Murres, Uria aalge) of birds shot by hunters around the Newfoundland coast during the winters of 1996-1998. We observed that the frequency of empty stomachs was greater in our study than in a similar study conducted during 1984-1986. We found no difference in the proportion of fish in the diet between the 1980s and the 1990s, however, Arctic cod (Boreogadus saida; from 55 to 12%) and capelin (Mallotus villosus; from 28 to 6%) decreased in frequency of occurrence. The proportion of stomachs containing crustaceans and squid did not change between the 1980s and 1990s, but hyperiid amphipods (Parathemisto spp.) replaced euphausiids (Thysanoessa spp.) as the predominant crustacean. Changes in murre winter diet off the coast of Newfoundland corroborate other sources of information indicating that major changes in the distribution and biology of marine organisms occurred in the Northwest Atlantic during the 1990s.

Ecological relationships between two sympatric congeneric species, Common Murres and Thick-billed Murres, Uria aalge and U. lomvia, breeding in the Barents Sea

1997 ◽  
Vol 75 (4) ◽  
pp. 618-631 ◽  
Author(s):  
R. T. Barrett ◽  
M. Asheim ◽  
V. Bakken
Keyword(s):  
Barents Sea ◽  
Dive Depth ◽  
Egg Laying ◽  
Clupea Harengus ◽  
Breeding Ecology ◽  
Uria Aalge ◽  
Common Murre ◽  
The Barents Sea ◽  
Common Murres ◽  
Capelin Mallotus Villosus

Concurrent studies of the breeding ecology of Common Murres and Thick-billed Murres, Uria aalge and U. lomvia, on Hornøya, a colony in northern Norway, showed significant differences between the species in the timing of egg laying but no consistent differences in food choice, feeding frequency and rhythm, dive depth, or chick growth. Both species fed their chicks on capelin, Mallotus villosus, sand lance Ammodytes sp., and herring Clupea harengus. However, on Bear Island in the Barents Sea, the diet differed significantly, with Common Murre chicks being fed nearly exclusively capelin while Thick-billed Murre chicks received capelin, squid Gonatus fabricii, Arctic cod, Boreogadus saida, sculpins (Cottidae), shannies Lumpenus sp., and eelpouts (Zoarcidae). The lack of dietary segregation on Hornøya was in strong contrast with the results of earlier studies of sympatrically breeding murres and was probaby due to a near superabundance of food around the colony.

Ecological relationships between Common Murres, Uria aalge, and Thick-billed Murres, Uria lomvia, at the Gannet Islands, Labrador. II. Breeding success and site characteristics

1987 ◽  
Vol 65 (7) ◽  
pp. 1630-1637 ◽  
Author(s):  
T. R. Birkhead ◽  
D. N. Nettleship
Keyword(s):  
Breeding Success ◽  
Breeding Site ◽  
Uria Aalge ◽  
Uria Lomvia ◽  
Short Supply ◽  
Breeding Sites ◽  
Ecological Relationships ◽  
Site Characteristics ◽  
Common Murres ◽  
Flat Ground

At the Gannet Islands, Labrador, the proportion of Thick-billed Murres (Uria lomvia) that successfully reared a chick that left the colony was significantly lower (mean = 63%) than that of Common Murres (Uria aalge; 82%) in each of 3 years of study. The physical and social features of the breeding site were the only factors known to influence breeding success. For both murre species, breeding success increased with ledge width, and whereas most Common Murres bred on the widest ledges, relatively few Thick-billed Murres did so. The success of each species did not differ significantly on ledges of the same width. We suggest that Common and Thick-billed murres competed for breeding sites and that Common Murres obtained a disproportionate share of the "best" sites. This occurred because Common Murres outnumbered Thick-billed Murres by about 40:1 and because cliff habitat was in short supply. Whereas Thick-billed Murres bred only on cliffs, Common Murres were able to breed on cliffs and flat ground nearer sea level. Additional circumstantial evidence supports the idea that Common and Thick-billed murres at the Gannet Islands compete for breeding sites.

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.

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