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

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.

1987 ◽  
Vol 65 (7) ◽  
pp. 1621-1629 ◽  
Author(s):  
T. R. Birkhead ◽  
D. N. Nettleship

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.


2015 ◽  
Vol 93 (6) ◽  
pp. 447-460 ◽  
Author(s):  
L. McFarlane Tranquilla ◽  
W.A. Montevecchi ◽  
A. Hedd ◽  
P.M. Regular ◽  
G.J. Robertson ◽  
...  

To study the influence of inter- and intra-specific interactions on patterns of ecological segregation in nonbreeding habitat, we used geolocators to track year-round movements of congeneric and partially sympatric Thick-billed Murres (Uria lomvia (L., 1758)) and Common Murres (Uria aalge (Pontoppidan, 1763)) from seven Canadian colonies during 2007–2011. Locations from 142 individuals were (i) examined for species- and colony-specific spatiotemporal patterns, (ii) mapped with environmental data, and (iii) used to delineate core wintering areas. Compared with Common Murres, Thick-billed Murres dispersed across a wider range of latitudes and environments, had larger winter ranges, and showed greater variation in seasonal timing of movements. These interspecific differences were consistent at two scales: among colonies spanning a wide latitudinal range and at a sympatric colony. Intraspecifically, nonbreeding ecological segregation was more pronounced among colonies of Thick-billed Murres than of Common Murres: colonies of Thick-billed Murres tended to follow distinct movement patterns and segregate by latitude, whereas colonies of Common Murres segregated very little; moreover, the extent of segregation was more variable among Thick-billed Murres than Common Murres. For Thick-billed Murres, rather than complete divergence of winter ecological niche from Common Murres, we found a “widening” of an overlapping niche. This strategy of increased movement flexibility may enable Thick-billed Murres to mitigate competition both intra- and inter-specifically; we propose this movement strategy may have played a role in species divergence.


2014 ◽  
Vol 128 (1) ◽  
pp. 72 ◽  
Author(s):  
Donald W. Pirie-Hay ◽  
Alexander L. Bond

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.


1997 ◽  
Vol 75 (4) ◽  
pp. 618-631 ◽  
Author(s):  
R. T. Barrett ◽  
M. Asheim ◽  
V. Bakken

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.


1999 ◽  
Vol 77 (8) ◽  
pp. 1278-1287 ◽  
Author(s):  
Rachel Bryant ◽  
Ian L Jones ◽  
J Mark Hipfner

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.


1996 ◽  
Vol 6 (3) ◽  
pp. 261-269 ◽  
Author(s):  
Julia K. Parrish ◽  
Robert T. Paine

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.


The Auk ◽  
2021 ◽  
Author(s):  
Tim R Birkhead ◽  
Jamie E Thompson ◽  
Amelia R Cox ◽  
Robert D Montgomerie

Abstract We studied the ground colors and maculations of 161 Common Murre (Uria aalge) eggs laid by 43 females in 3 small breeding groups on the cliffs of Skomer Island, Wales, in 2016–2018. Both the colors and maculations varied much more among than within females, providing quantitative evidence for the egg traits that might facilitate the parents’ ability to identify their own eggs on the crowded breeding ledges where the density is typically ~20 eggs m–2. Ground colors had a trimodal distribution of hue values (whitish to pale brown, pale blue, or vivid blue-green) and maculations ranged from none to complex squiggles and blotches. The eggs laid by each female in different years were similar to one another, and replacement eggs laid by females within years were also more similar to their first egg than to other eggs in the same breeding group. Egg appearance did not differ among the 3 breeding groups that we studied. Our findings thus support anecdotal observations that, within and between years, female Common Murres lay eggs that have similar ground colors and maculations. We do not, however, find evidence that there is much difference among the eggs laid in different parts of a colony.


1987 ◽  
Vol 65 (6) ◽  
pp. 1530-1534 ◽  
Author(s):  
John F. Piatt ◽  
Ruth L. McLagan

Attendance patterns of common murres (Uria aalge) at Cape St. Mary's, Newfoundland, were observed during hatching to post-fledging periods of 1980 to 1984. Six study plots on breeding ledges (ca. 450 birds total) and a "club" on the water were monitored for seasonal fluctuations in numbers attending. Attendance on ledges was similar between years, being relatively stable from hatching through to median fledging, and declining steadily thereafter. Attendance at the club usually peaked between median hatching and fledging, then declined rapidly during the fledging period. Numbers of murres attending neighboring study plots were often significantly correlated, but correlations were much weaker between distant plots. There were few significant correlations between attendance and wind speed or tidal oscillations in any year of study. Numbers of murres attending individual study plots varied significantly between years; four declined, one increased, and one showed no significant change. Overall, there was a small decline in total numbers of murres attending all study plots between 1980 and 1984.


1993 ◽  
Vol 71 (7) ◽  
pp. 1474-1477 ◽  
Author(s):  
V. L. Friesen ◽  
R. T. Barrett ◽  
W. A. Montevecchi ◽  
W. S. Davidson

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.


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