Characteristics of a Rapidly Increasing Colony of Double-Crested Cormorants (Phalacrocorax auritus) in Lake Ontario: Population Size, Reproductive Parameters and Band Recoveries

1994 ◽  
Vol 20 (2) ◽  
pp. 443-456 ◽  
Author(s):  
D.V. Chip Weseloh ◽  
Peter J. Ewins
Keyword(s):  
Population Size ◽  
Lake Ontario ◽  
Reproductive Parameters ◽  
Phalacrocorax Auritus

scholarly journals Changes in the reproductive parameters of female harp seals (Pagophilus groenlandicus) in the Northwest Atlantic

2009 ◽  
Vol 67 (2) ◽  
pp. 304-315 ◽  
Author(s):  
Becky Sjare ◽  
Garry B. Stenson
Keyword(s):  
Environmental Factors ◽  
Population Size ◽  
Sexual Maturity ◽  
Reproductive Parameters ◽  
Northwest Atlantic ◽  
Pagophilus Groenlandicus ◽  
Long Term Trends ◽  
The Mean ◽  
The 1950S

Abstract Sjare, B., and Stenson, G. B. 2010. Changes in the reproductive parameters of female harp seals (Pagophilus groenlandicus) in the Northwest Atlantic. – ICES Journal of Marine Science, 67: 304–315. Changes in female harp seal (Pagophilus groenlandicus) reproductive parameters from 1980 to 2004, and long-term trends since the early 1950s, are evaluated. Estimates of the total number of seals in the Northwest Atlantic declined from ∼3.0 million in the 1950s to 1.8 million in the early 1970s, then increased steadily to 5.5 million in 1996, at which relatively stable level it has remained since. Pregnancy rates increased from ∼86% in the 1950s to a high of 98% in the mid-1960s, then declined to ∼65–70% by the early 1990s; the rate then varied between 45 and 70% from 2000 to 2004. Concurrently, the mean age at sexual maturity decreased from 5.8 (s.e = 0.02) years in the mid-1950s to 4.1 (s.e. = 0.02) in the late 1970s, increased to 5.5 (s.e. = 0.03) years by the early 1990s, and peaked at 5.7 (s.e. = 0.01) in 1995. From 2000 to 2004, mean age varied from 4.9 (s.e. = 0.01) to 6.0 (s.e. = 0.01) years. Although the direction of change in each of the parameters was consistent with a density-dependent response, changes in population size explained relatively little of the variability observed, suggesting that other ecological or environmental factors were influential.

scholarly journals Population structures and seasons affected flowering, pollination and reproductive outputs of sandalwood in Gunung Sewu, Java, Indonesia

2018 ◽  
Vol 10 (1) ◽  
pp. 12-26 ◽  
Author(s):  
YENI W.N. RATNANINGRUM ◽  
SAPTO INDRIOKO ◽  
ENY FARIDAH ◽  
ATUS SYAHBUDIN
Keyword(s):  
Population Size ◽  
Inbreeding Depression ◽  
Rainy Season ◽  
Flowering Period ◽  
Reproductive Parameters ◽  
The South ◽  
South Eastern ◽  
Population Structures

Ratnaningrum YWN, Indrioko S, Faridah E, Syahbudin A. 2018. Population structures and seasons affected flowering, pollination and reproductive outputs of sandalwood in Gunung Sewu, Java, Indonesia. Nusantara Bioscience 10: 12-26. Sandalwood was the origin to the south-eastern islands of Indonesia, but is recently occurred as new landraces in Gunung Sewu Geopark, Java, Indonesia. This study compared flowering and pollination, and their effect on reproductive outputs, among sandalwood populations in Gunung Sewu, during the dry and rainy season of 2016 flowering period. Flowering and pollination rate differed significantly between seasons but were similar among sites. Oppositely, reproductive outputs differed significantly among sites, but were similar between seasons. The rainy season produced more flowers and pollination. Pollination was less correlated to flowers abundance, but more affected by population size. The higher and cooler population visited more by Dipterans (31.8% to 32.6%) and Hymenopterans (28.2% to 30%), while the warmer, lower sites dominated by Lepidopterans (37.2% to 43%) and Dipterans (32.9% to 38.2%). Higher population received fewer visits, but more visitors diversity (28 families). In contrast, lower sites received more visits, but with less diversity (20 families). Most insect families were considered “Rare” and “Occasional”. However, pooled altogether, the whole families of Lepidopterans and Dipterans considered “Frequent” and “Effective”. The Hymenopterans considered “Frequent” and “Effective” at Nglanggeran and Wanagama. The Cicadellidae of Coleopterans, along with arachnids and grasshoppers, were considered robbers. All of the agents were diurnal. However, the time of activity was varied. Rainy season gained more flowers and visits, but in contrast, resulted in fewer fruits at all sites. Both flowers abundance and pollination were negatively correlated to the reproductive parameters. Populations might gain more flowers and visits, but the reproductive outputs were significantly lower. Particularly in the clonalized and lower heterozygosity populations, more flowers increased geitonogamy which may lead to inbreeding depression.

Fatty acids, stable isotopes, and regurgitate reveal diet differences between Lake Ontario and Lake Erie double-crested cormorants ( Phalacrocorax auritus )

2017 ◽  
Vol 43 (3) ◽  
pp. 132-140 ◽  
Author(s):  
L.E. King ◽  
S.R. de Solla ◽  
J.R. Marentette ◽  
R.A. Lavoie ◽  
T.K. Kyser ◽  
...  
Keyword(s):  
Fatty Acids ◽  
Stable Isotopes ◽  
Lake Erie ◽  
Lake Ontario ◽  
Phalacrocorax Auritus

The impact of double-crested cormorant (Phalacrocorax auritus) predation on anadromous alewife (Alosa pseudoharengus) in south-central Connecticut, USA

2009 ◽  
Vol 66 (2) ◽  
pp. 177-186 ◽  
Author(s):  
Christopher M. Dalton ◽  
David Ellis ◽  
David M. Post
Keyword(s):  
Population Size ◽  
Alosa Pseudoharengus ◽  
Commercial Fishery ◽  
Phalacrocorax Auritus ◽  
Bioenergetic Model ◽  
South Central ◽  
Population Sizes ◽  
The Impact

The decline of anadromous alewife ( Alosa pseudoharengus ) threatens an important recreational and commercial fishery. While the cause of this decline is uncertain, predators could be trapping alewives at low abundance by preying on them during spawning migrations. Here we investigate the impact of predation by double-crested cormorants ( Phalacrocorax auritus ) on spawning adult alewives in south-central Connecticut, USA. We use a bioenergetic model together with estimates of cormorant diets and cormorant and alewife population sizes to estimate the consumption of alewives by cormorants both in Bride Lake, Connecticut, and regionally. We find that cormorants are important predators of spawning adult alewives at Bride Lake but do not have a notable impact on alewife mortality or population size. We also find that cormorants have little effect on alewife populations across south-central Connecticut because few alewives are consumed away from Bride Lake. We conclude that cormorants are important predators for anadromous alewives, but do not pose an immediate threat to the recovery of regional alewife stocks.

scholarly journals Sterols and stanols as novel tracers of waterbird population dynamics in freshwater ponds

2018 ◽  
Vol 285 (1877) ◽  
pp. 20180631 ◽  
Author(s):  
Kathryn E. Hargan ◽  
Emily M. Stewart ◽  
Neal Michelutti ◽  
Christopher Grooms ◽  
Linda E. Kimpe ◽  
...  
Keyword(s):  
Lake Ontario ◽  
Phalacrocorax Auritus ◽  
Bird Abundance ◽  
Reliable Technique ◽  
Freshwater Ponds ◽  
Waterbird Species ◽  
Isotopic Methods ◽  
Reduced Products ◽  
Larus Delawarensis ◽  
Omnivorous Diet

With the expansion of urban centres in the mid-twentieth century and the post-1970 decrease in pesticides, populations of double-crested cormorants ( Phalacrocorax auritus ) and ring-billed gulls ( Larus delawarensis ) around Lake Ontario (Canada and USA) have rapidly rebounded, possibly to unprecedented numbers. Along with the use of traditional palaeolimnological methods (e.g. stable isotopes, biological proxies), we now have the capacity to develop specific markers for directly tracking the presence of waterbirds on nesting islands. Here, we apply the use of lipophilic sterols and stanols from both plant and animal-faecal origins as a reliable technique, independent of traditional isotopic methods, for pinpointing waterbird arrival and population growth over decadal timescales. Sterol and stanol concentrations measured in the guano samples of waterbird species were highly variable within a species and between the three species of waterbirds examined. However, cholesterol was the dominant sterol in guano, and phytosterols were also high in ring-billed gull guano. This variability highlights a specialist piscivorous diet for cormorants compared to a generalist, omnivorous diet for gulls, which may now often include grain and invertebrates from agricultural fields. A ratio that includes cholesterol and sitosterol plus their aerobically reduced products (cholestanol, stigmastanol) best explained the present range of bird abundance across the islands and was significantly correlated to sedimentary δ 15 N. Overall, we demonstrate the use of sterols and stanols as a direct means for tracking the spatial and temporal presence of waterbirds on islands across Lake Ontario, and probably elsewhere.

Reduction of spermatogonia and testosterone in rat testes flown on space lab-3

1986 ◽  
Vol 44 ◽  
pp. 248-249
Author(s):  
Delbert E. Philpott ◽  
W. Sapp ◽  
C. Williams ◽  
T. Fast ◽  
J. Stevenson ◽  
...  
Keyword(s):  
Social Interaction ◽  
Social Status ◽  
Population Size ◽  
Physiological Response ◽  
Social Rank ◽  
Reproductive Function ◽  
Testicular Development ◽  
Organ Weights ◽  
Reproductive Maturation ◽  
Metabolic Activities

Space Lab 3 (SL-3) was flown on Shuttle Challenger providing an opportunity to measure the effect of spaceflight on rat testes. Cannon developed the idea that organisms react to unfavorable conditions with highly integrated metabolic activities. Selye summarized the manifestations of physiological response to nonspecific stress and he pointed out that atrophy of the gonads always occurred. Many papers have been published showing the effects of social interaction, crowding, peck order and confinement. Flickinger showed delayed testicular development in subordinate roosters influenced by group numbers, social rank and social status. Christian reported increasing population size in mice resulted in adrenal hypertrophy, inhibition of reproductive maturation and loss of reproductive function in adults. Sex organ weights also declined. Two male dogs were flown on Cosmos 110 for 22 days. Fedorova reported an increase of 30 to 70% atypical spermatozoa consisting of tail curling and/or the absence of a tail.

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