Relative contribution of euphausiid prey species and timing of breeding to Cassin's auklet Ptychoramphus aleuticus growth: within-season effects

2008 ◽  
Vol 39 (2) ◽  
pp. 178-188 ◽  
Author(s):  
Christine L. Abraham
Keyword(s):  
Prey Species ◽  
Timing Of Breeding ◽  
Relative Contribution ◽  
Cassin's Auklet ◽  
Ptychoramphus Aleuticus

Cassin's Auklet (Ptychoramphus aleuticus)

2020 ◽  
Author(s):  
David G. Ainley ◽  
D. A. Manuwal ◽  
Josh Adams ◽  
A. C. Thoresen
Keyword(s):  
Cassin's Auklet ◽  
Ptychoramphus Aleuticus

The abundance and effects of ticks (Ixodes uriae) on nestling Cassin's Auklets (Ptychoramphus aleuticus) at Triangle Island, British Columbia

1996 ◽  
Vol 74 (8) ◽  
pp. 1585-1589 ◽  
Author(s):  
Y. E. Morbey
Keyword(s):  
Tick Infestation ◽  
Host Record ◽  
New Host ◽  
Ixodes Uriae ◽  
New Host Record ◽  
Cassin's Auklet ◽  
Peak Mass ◽  
The Common ◽  
Ptychoramphus Aleuticus ◽  
Wing Growth

Cassin's Auklet (Ptychoramphus aleuticus) nestlings hosted the common seabird tick Ixodes uriae. This is a new host record for this species of tick. Ixodes uriae were distributed nonrandomly on nestlings within and among sites. Soil substrate was thought to be an important factor influencing tick distribution. Nestlings with severe tick infestation had slower rates of wing growth, reached peak mass at older ages, and fledged with shorter wings at older ages than nestlings with fewer ticks. By remaining in the nest for longer periods, nestlings with severe tick infestation may have been compensating for the delay in wing development.

scholarly journals Introduced mammals, vegetation changes and seabird conservation on the Scott Islands, British Columbia, Canada

2010 ◽  
Vol 20 (3) ◽  
pp. 295-305 ◽  
Author(s):  
J. MARK HIPFNER ◽  
MOIRA J. F. LEMON ◽  
MICHAEL S. RODWAY
Keyword(s):  
British Columbia ◽  
American Mink ◽  
Breeding Population ◽  
Vegetation Changes ◽  
Population Declines ◽  
Seabird Conservation ◽  
Time Period ◽  
Cassin's Auklet ◽  
Vegetation Surveys ◽  
Ptychoramphus Aleuticus

SummaryThe Scott Islands, British Columbia, Canada, support the largest aggregation of breeding seabirds in the eastern Pacific Ocean south of Alaska. However, large seabird populations were eradicated by American Mink Neovison vison and Raccoons Procyon lotor introduced to Lanz and Cox islands in the 1930s, while the ecological consequences of the introduction of European Rabbits Oryctolagus cuniculus to Triangle Island in the 1920s are unknown. We have seen dramatic changes in the vegetation on Triangle Island in recent decades, chiefly a decrease in Tufted Hairgrass Deschampsia cespitosa cover and a concomitant increase in Salmonberry Rubus spectabilis cover. We carried out vegetation surveys at Triangle Island (1989 and 2004) and its nearest neighbour, rabbit-free Sartine Island (1987 and 2006), to test the hypothesis that rabbits have caused these changes. We found, however, that similar changes have occurred at Sartine Island as at Triangle Island over the same time period. Because these two islands support the bulk of the world's breeding population of Cassin's Auklet Ptychoramphus aleuticus, a small seabird that selects grass-covered habitat but avoids tall Salmonberry for nesting, the vegetation changes raise serious concerns for a species that has experienced dramatic population declines in recent years. Restoration of seabird nesting habitat by removing American Mink and Raccoons from Lanz and Cox islands will be vital for long-term seabird conservation in the Scott Islands.

Diving depths and diet of Cassin's Auklet at Reef Island, British Columbia

1990 ◽  
Vol 68 (7) ◽  
pp. 1572-1577 ◽  
Author(s):  
Alan E. Burger ◽  
David W. Powell
Keyword(s):  
British Columbia ◽  
Juvenile Fish ◽  
Ammodytes Hexapterus ◽  
Queen Charlotte Islands ◽  
Cassin's Auklet ◽  
Ptychoramphus Aleuticus

Diving depths of Cassin's Auklets (Ptychoramphus aleuticus) breeding at Reef Island, Queen Charlotte Islands, British Columbia, were measured with miniature gauges attached to the birds. Maximum diving depths of 22 birds averaged 28 m, with a mode of 40 m. A time-at-depth recorder showed that one auklet dived to 29 m, but spent 80% of its time underwater at 3–13 m. Food delivered in gular pouches to chicks contained mainly euphausiids (predominantly Thysanoessa spinifera) and juvenile fish (Ammodytes hexapterus), with lesser amounts of copepods, amphipods, small pandalid shrimps, Brachyura larvae, and ctenophores. Euphausiid meals were most common during spring tides. Auklets that delivered significant amounts of euphausiids appeared to have dived deeper than those that delivered fish.

Stable foraging areas and variable chick diet in Cassin's auklets (Ptychoramphus aleuticus) off southern California

2004 ◽  
Vol 82 (10) ◽  
pp. 1578-1595 ◽  
Author(s):  
Josh Adams ◽  
John Y Takekawa ◽  
Harry R Carter
Keyword(s):  
Southern California ◽  
Prey Availability ◽  
California Current ◽  
Breeding Ecology ◽  
Foraging Area ◽  
Cassin's Auklet ◽  
Prey Resources ◽  
Ptychoramphus Aleuticus ◽  
Second Clutch ◽  
Breeding Seasons

Planktivorous seabirds readily respond to changes in marine ecosystems and have the ability to integrate information regarding variability in abundance, availability, and community composition of key prey resources. We studied the foraging and breeding ecology of the Cassin's auklet, Ptychoramphus aleuticus (Pallas, 1811), off southern California during three breeding seasons (1999–2001), when large intra- and inter-annual variability occurred in local oceanographic conditions during a prolonged La Niña event. Radio-marked parents used consistent core foraging areas within 30 km of their colony, aggregated in shelf waters (<200 m depth), and occasionally foraged in deeper waters. Parents delivered primarily euphausiids, pelagic larval-juvenile fishes, and minor amounts of cephalopods and other crustaceans. Whereas the euphausiid Thysanoessa spinifera Holmes, 1900 was most important during 1999 and 2001, Euphausia pacifica Hansen, 1911 replaced adult T. spinifera in 2000 after an anomalous eastward inflection of the California Current occurred near the auklets' foraging area. Differences in chick diets, however, did not significantly influence fledging success and growth among first chicks, but the proportion of pairs successfully fledging an alpha chick and initiating a second clutch was exceptional in 1999 (63%) and 2000 (75%), and less in 2001 (7%). We suggest that dietary composition was influenced by modified prey availability driven in part by fluctuations in regional upwelling and circulation.

scholarly journals A Comparison of Variability in Two Cassin’s Auklet (Ptychoramphus aleuticus) Colonies Using Spline-based Nonparametric Models

2013 ◽  
Vol 4 (1) ◽  
pp. 63-85
Author(s):  
Dean Koch
Keyword(s):  
Growth Rate ◽  
Reproductive Performance ◽  
Coefficient Of Variation ◽  
Small Scale ◽  
Regression Spline ◽  
Ecological Variability ◽  
Nonparametric Models ◽  
Cassin's Auklet ◽  
Ptychoramphus Aleuticus ◽  
Over Time

While variability in the reproductive performance of a population over time is a familiar and useful concept to ecologists, it can be difficult to capture mathematically. Commonly used ecological variability statistics, such as the standard deviation of the logarithm and coefficient of variation, discard the time-ordering of observations and consider only the unordered response variable values. We used a relatively new methodology, the cubic regression spline (a flexible curve fitted to a scatterplot of data), both to illustrate trends in reproductive performance over time and to explore the utility of the cubic regression spline roughness penalty (J) as a statistic for measuring variability while retaining time-ordering information. We concluded that although J measures variability in a mathematical sense, it can be inappropriate in a population ecology context because of sensitivity to small-scale fluctuations. To illustrate our methodology, we used the CRS approach in an analysis of historical data from two Cassin’s Auklet colonies located on Frederick and Triangle Islands in coastal BC, developing a model for the annual mean nestling growth rate on each island over seven contiguous years. Model selection indicated a complex (nonlinear) trend in growth rate on both islands. We report higher variability in the resident bird population of Triangle Island than Frederick Island, based on a comparison of the fitted curves, and the values of the coefficient of variation and population variability summary statistics.

scholarly journals Ocean climate and El Niño impacts on survival of Cassin's Auklets from upwelling and downwelling domains of British Columbia

2005 ◽  
Vol 62 (12) ◽  
pp. 2841-2853 ◽  
Author(s):  
Douglas F Bertram ◽  
Anne Harfenist ◽  
Barry D Smith
Keyword(s):  
British Columbia ◽  
El Niño ◽  
El Nino ◽  
Marine Ecosystem ◽  
California Current ◽  
Ocean Climate ◽  
The North ◽  
Mortality Response ◽  
Cassin's Auklet ◽  
Ptychoramphus Aleuticus

We report on the survival of populations of Cassin's Auklet (Ptychoramphus aleuticus) that breed on two oceanic colonies in British Columbia: Triangle Island, near the northern end of the California Current Ecosystem, and Frederick Island to the north in the Alaska Current Ecosystem. We captured and banded birds at both colonies from 1994 to 2000 and analyzed the recovery data with the computer program MARK. Average local adult annual survival (± standard error) was significantly lower (p = 0.0001) on Triangle Island (0.71 ± 0.02) than that on Frederick Island (0.80 ± 0.02), likely a result of poor production in the California Current Ecosystem during the 1990s. Coincident with a strong El Niño event, survival in 1997-1998 fell in unison to the lowest values observed for both colonies (to 0.54 ± 0.05 and 0.64 ± 0.04, respectively, for adults). A common winter environment in the California Current Ecosystem could explain the unified mortality response of both British Columbia populations to an exceptionally poor food period. The seabird colonies in this study occupy key positions in relation to major oceanographic domains and hence provide unique platforms for investigations of marine ecosystem response to ocean climate variability in the Northeast Pacific Ocean.

Egg Formation in Cassin's Auklet

The Auk ◽  
1986 ◽  
Vol 103 (4) ◽  
pp. 682-693 ◽  
Author(s):  
Lee B. Astheimer
Keyword(s):  
Ring Structure ◽  
Egg Laying ◽  
Primordial Follicles ◽  
Additional Information ◽  
Egg Formation ◽  
Cassin's Auklet ◽  
Lag Period ◽  
Egg Composition ◽  
Ptychoramphus Aleuticus ◽  
Egg Removal

Abstract Female Cassin's Auklets (Ptychoramphus aleuticus) were given oral doses of lipophilic and proteophilic dyes during their prelaying period. Yolk ring structure in freshly laid eggs was analyzed to determine the timing of yolk deposition using the dye-stained layer as a date marker within the yolk. Additional information from necropsies of five females killed at specific intervals during the formation of a replacement egg indicated that only a single follicle enlarges in the ovary during a reproductive event and this yolk requires about 8 days to complete rapid yolk deposition (RYD). Once RYD is completed, the egg is not laid for a period of 4.2 ± 1.0 days, an interval termed the lag period (Astheimer et al. 1979). Albumen synthesis appears to begin at, or just before, completion of the yolk and continues until approximately 1 day before oviposition. During this time, however, the yolk remains in the follicle. Replacement eggs are laid 14.5 ± 1.7 days following egg removal or natural loss. Combining the above information with egg composition data, the daily deposition of lipid and protein from the female into the egg was computed. Evidence from the size distribution of small (<5 mm) primordial follicles suggests that the auklet ovary undergoes a cycle of follicular growth and atresia before a single follicle is selected for RYD. Based on these findings, and the correlation between initiation of spring egg laying and decreased sea surface temperatures for Farallon Island auklets, I suggest that the onset of RYD is modulated by environmental conditions.

scholarly journals Spatial differences in prey preference by tigers across the Bangladesh Sundarbans reveal a need for customised strategies to protect prey populations

2020 ◽  
Vol 43 ◽  
pp. 65-73
Author(s):  
MA Aziz ◽  
MA Islam ◽  
J Groombridge
Keyword(s):  
Prey Species ◽  
Species Conservation ◽  
Prey Preference ◽  
Panthera Tigris ◽  
Relative Contribution ◽  
Spotted Deer ◽  
Spatial Differences ◽  
Tiger Population ◽  
The Sundarbans ◽  
Wild Pig

The Sundarbans is the only mangrove habitat in the world to support tigers Panthera tigris, whose persistence there is believed to be dependent on a very limited number of prey species. Conservation managers therefore need to understand how tigers utilise available prey species on a spatial scale in order to formulate a prey-based protection strategy for this global-priority tiger landscape. A total of 512 scat samples were collected during a survey of 1984 km2 of forest across 4 sample blocks in the 6017 km2 of the Bangladesh Sundarbans. Analysis of scat composition and prey remains reliably identified 5 major prey species, of which spotted deer Axis axis and wild pig Sus scrofa contributed a cumulative biomass of 89% to tiger diet. Tiger preference for prey species was highly skewed towards spotted deer and wild pig, but the relative contribution of these 2 species differed significantly across the 4 study areas, which spanned the Sundarbans, demonstrating important spatial patterns of tiger prey preference across the Sundarbans landscape. Given the comparatively limited number of prey species available to support the dwindling tiger population, different strategies are needed in different parts of the Sundarbans to support tiger populations and to protect spotted deer and wild pig populations from unabated poaching.

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