The breeding biology of two Lake Erie herring gull colonies

1977 ◽  
Vol 55 (5) ◽  
pp. 796-805 ◽  
Author(s):  
Ralph D. Morris ◽  
Gerard T. Haymes

The breeding biology of two Lake Erie herring gull colonies was studied from 1973 to 1976, emphasizing effects of clutch size and time of clutch initiation on reproductive success. In 1976, incubation attention of two-egg and three-egg clutches started early and late in the season was measured with a 20-pen event recorder. Chlorinated hydrocarbon residues in eggs were assessed in 2 years. Nest density was greater, clutch initiation more synchronized, and hatching success higher at one of the colonies. Hatching success and fledging success were independent of clutch size bin early nesters were more successful than late nesters. Differences in hatching success between two-egg and three-egg clutches were a function of time of clutch initiation such that the clutch size with the greater proportion of its nests in the early period had a higher hatching success. The reproductive success of the Lake Erie colonies was intermediate among rates reported for other Great Lakes colonies but below those of most eastern North American or European colonies. There were no significant differences in the incubation attention between two-egg clutches and three-egg clutches or between early and late three-egg clutches. Most clutches were incubated greater than 95% of the time although clutches incubated less than 75% realized the same hatching success.


The Auk ◽  
1984 ◽  
Vol 101 (4) ◽  
pp. 848-854 ◽  
Author(s):  
Susan J. Hannon ◽  
James N. M. Smith

Abstract In many species, adult birds lay earlier and have higher reproductive success than do yearlings. We found no difference, however, between adult and yearling female Willow Ptarmigan (Lagopus lagopus alexandrae) in date of clutch initiation, clutch size, hatching success, number of fledged young, or territory size. Adult females defended their broods more vigorously, and more were observed with broods, a situation suggesting that more yearlings lost their eggs or young and did not renest. Pairs composed of two adults produced more fledged young than did pairs composed of two yearlings, but clutch size and date of clutch initiation were similar in the two groups. We suggest that the following factors may allow yearlings to reproduce almost as successfully as adults: (1) a reduction in competition with adults for territories because of high population turnover, (2) the presence of extensive male parental care and precocial young, and (3) a dependence on a food source that is readily available and can be obtained without specialized foraging skills.



1985 ◽  
Vol 63 (3) ◽  
pp. 607-611 ◽  
Author(s):  
Ralph D. Morris ◽  
John W. Chardine

The substrate at a herring gull (Larus argentatus) colony on Lake Erie near Port Colborne, Ontario (Lighthouse), was completely covered by a thick layer of ice throughout April and early May 1982. Egg laying normally begins at this location in mid-April. An adjacent herring gull colony (Canada Furnace) was ice free. Herring gull pairs at the Lighthouse colony defended territories on top of the ice but only 3 of about 90 pairs built nests on the ice. Birds neither deserted the colony nor moved within it to ice-free areas as these became available. The mean date of egg laying at the Lighthouse colony in 1982 was about 2 weeks later than in the previous year. At the adjacent Canada Furnace colony, there was no difference in the mean date of egg laying between the 2 years. There were no differences in the distribution of clutch sizes, mean clutch sizes, or hatching success of three-egg clutches laid within ± 1 SD of the mean date of egg laying at either colony in the 2 years. By these measures, the ice-induced delay in breeding chronology of birds at the Lighthouse colony in 1982 did not adversely effect reproductive performance in that year.



2008 ◽  
Vol 56 (6) ◽  
pp. 389 ◽  
Author(s):  
Luis Ortiz-Catedral ◽  
Dianne H. Brunton

At least four populations of the red-crowned parakeet (Cyanoramphus novaezelandiae) have been established via translocation within New Zealand over the last 40 years, but reproductive parameters of these populations have not been documented. We quantified differences in clutch parameters and reproductive success for a translocated population of this species on Tiritiri Matangi Island over two breeding seasons. Overall clutch parameters and estimates of reproductive success were consistent with reported values from natural populations. However, we found previously unreported differences in clutch size, hatching success and brood size between breeding seasons. The number of fledglings produced per breeding pair increased significantly from 1.4 to 3.4 fledglings during our two-year study. In contrast, egg volume and fertility per clutch did not vary during the same period. Overall, 7 eggs were laid per breeding pair but only 2.22 nestlings fledged, representing a 63.8% loss of initial reproductive potential. Losses during the incubation stage were caused by partial and total hatching failure, whereas starvation of nestlings caused all losses during the brood-rearing stage. Hatching success during our study was lower than that reported for wild populations of this and other parrot species, and remained lower even during the most productive breeding season. We found no cases of predation on eggs or nestlings during our study despite the presence of native and exotic avian predators on Tiritiri Matangi Island. We show that clutch size, brood size and changes in loss between breeding seasons are determinants of reproductive output in translocated red-crowned parakeet and also that reproductive output can vary greatly between breeding seasons. Finally, if reduced hatching success is the result of small founder size, management of parakeets should consider the movement of larger and more genetically diverse flocks.



1977 ◽  
Vol 55 (10) ◽  
pp. 1766-1766
Author(s):  
Ralph D. Morris ◽  
Gerard T. Haymes


The Auk ◽  
2003 ◽  
Vol 120 (4) ◽  
pp. 1128-1139
Author(s):  
Myriam E. Mermoz ◽  
Juan C. Reboreda

Abstract Shiny Cowbirds (Molothrus bonariensis) often parasitize larger hosts. It has been proposed that larger hosts are preferred by that parasite because they provide higher reproductive success, but available data are quite variable. We studied the reproductive success of Shiny Cowbirds in nests of Brown-and-yellow Marshbirds (Pseudoleistes virescens), a larger and often multiply parasitized host. To estimate the extent of interspecific competition, we compared the hatching success of parasite eggs in nests with and without reduction of the clutch size of the host as a result of egg punctures inflicted by the parasite, and the survival and growth of parasite chicks reared with and without host chicks. To estimate the extent of intraspecific competition, we compared Shiny Cowbird egg losses, hatching success, and chick survival in singly versus multiply parasitized nests. Reproductive success of Shiny Cowbirds was 8% with depredation causing 80% of losses. Clutch reduction due to egg punctures were higher in multiply than in singly parasitized nests, but it did not improve hatching success of parasite eggs. Neither survival nor growth of parasite chicks was affected by the presence of host chicks. Shiny Cowbird hatching success and chick survival did not differ between singly and multiply parasitized nests. Parasite chicks were smaller than same-age Brown-and-yellow Marshbird chicks. However, because parasite chicks hatched one or two days before host chicks and had a higher growth rate, they were the larger chicks in the nest. Overall Shiny Cowbird reproductive success in Brown-and-yellow Marshbird nests was apparently higher than that reported in other smaller or similar-sized hosts. We think that host life-history traits like large clutch size, a longer incubation period, and slower growth rate of chicks are responsible for the high reproductive success of Shiny Cowbirds with Brown-and-yellow Marshbirds.



1991 ◽  
Vol 69 (1) ◽  
pp. 168-175 ◽  
Author(s):  
Jordan B. Ignatiuk ◽  
Robert G. Clark

The breeding biology of American crows (Corvus brachyrhynchos) was studied in two areas (St. Denis and Elstow) of aspen parkland habitat in Saskatchewan, Canada, in 1987 and 1988. The St. Denis area had relatively more diverse land use and contained more wetlands than the Elstow area. Crows returned from winter ranges in early April and were frequently observed at breeding sites in late April, when nest building began. Overall, mean (± SD) clutch initiation dates were 6 May (± 6 days) at St. Denis and 10 May (± 6) at Elstow, but, in 1988, clutches were initiated about 6 days earlier at St. Denis than at Elstow (P < 0.05). Density of nests at St. Denis averaged twice that found at Elstow (0.70 and 0.35/km2, respectively; P < 0.05). Size of incubated clutches did not differ between years or areas, and averaged 4.8 ± 0.6 eggs (n = 104). Hatching success did not differ by year or area, but in 1987, nests at St. Denis produced nearly twice as many young as at Elstow. Brood losses resulted from predation, starvation, and possibly other factors. Chicks in smaller broods gained mass faster and fledged at a lighter mass than chicks in larger broods. There were no consistent differences between areas in the mass, bill length, and head–bill lengths of 22-day-old chicks. Young fledged when they were between 30 and 34 days old. Crows at St. Denis had higher reproductive success (1987), nested at greater densities (1988 and both years combined), and began egg laying earlier (1988) than at Elstow, suggesting that St. Denis was a more productive breeding habitat.



The Auk ◽  
1983 ◽  
Vol 100 (3) ◽  
pp. 658-669 ◽  
Author(s):  
Kit M. Kovacs ◽  
John P. Ryder

Abstract We studied female-female pairs of Ring-billed Gulls (Larus delawarensis) on Granite Island, northern Lake Superior, during the breeding seasons of 1979 and 1980. In 1979 the colony consisted of approximately 2,400 nesting pairs, with a total of 99 nests containing 5-7 eggs (superclutches). In 1980 the colony had increased in size to 2,600 nests and contained a total of 71 superclutches. We discuss the difficulty of distinguishing nests in which superclutches have been laid by female-female pairs from single-cup nests used by polygynous groups or from nests receiving dump eggs. Nests containing superclutches were larger than those containing normal-sized clutches. They were not differentially located by substrate, nest density, or location within the colony. Nearest-neighbour distance was also similar for the two clutch types. Eggs laid in superclutches were slightly smaller than those from normal-sized clutches (1-4 eggs) but did not differ in shape. Significantly more eggs from superclutches rolled from the nest or were destroyed or abandoned than from normal-sized clutches. The proportion of nests that hatched at least one chick did not differ significantly between the two clutch types. Hatching success for superclutches was 34% in 1979 and 30% in 1980, whereas for normal-sized clutches it was 77% in 1979 and 61% in 1980. Chicks from superclutches had a higher rate of mortality during the week following hatching than did chicks from normal-sized clutches. Chicks from the former hatched at significantly lighter weights than did those from the latter during both years of study, but their weights did not differ after the first week posthatch. Tarsal and culmen measurements followed a similar pattern to that of weight. Chicks from normal-sized clutches had a significantly higher fledging success than did those from superclutches. The reproductive success of four polygynous groups is also reported.



Author(s):  
Kristina Noreikienė ◽  
Kim Jaatinen ◽  
Benjamin B. Steele ◽  
Markus Öst

AbstractGlucocorticoid hormones may mediate trade-offs between current and future reproduction. However, understanding their role is complicated by predation risk, which simultaneously affects the value of the current reproductive investment and elevates glucocorticoid levels. Here, we shed light on these issues in long-lived female Eiders (Somateria mollissima) by investigating how current reproductive investment (clutch size) and hatching success relate to faecal glucocorticoid metabolite [fGCM] level and residual reproductive value (minimum years of breeding experience, body condition, relative telomere length) under spatially variable predation risk. Our results showed a positive relationship between colony-specific predation risk and mean colony-specific fGCM levels. Clutch size and female fGCM were negatively correlated only under high nest predation and in females in good body condition, previously shown to have a longer life expectancy. We also found that younger females with longer telomeres had smaller clutches. The drop in hatching success with increasing fGCM levels was least pronounced under high nest predation risk, suggesting that elevated fGCM levels may allow females to ensure some reproductive success under such conditions. Hatching success was positively associated with female body condition, with relative telomere length, particularly in younger females, and with female minimum age, particularly under low predation risk, showing the utility of these metrics as indicators of individual quality. In line with a trade-off between current and future reproduction, our results show that high potential for future breeding prospects and increased predation risk shift the balance toward investment in future reproduction, with glucocorticoids playing a role in the resolution of this trade-off.



2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Cynthia Reséndiz-Infante ◽  
Gilles Gauthier

AbstractMany avian migrants have not adjusted breeding phenology to climate warming resulting in negative consequences for their offspring. We studied seasonal changes in reproductive success of the greater snow goose (Anser caerulescens atlantica), a long-distance migrant. As the climate warms and plant phenology advances, the mismatch between the timing of gosling hatch and peak nutritive quality of plants will increase. We predicted that optimal laying date yielding highest reproductive success occurred earlier over time and that the seasonal decline in reproductive success increased. Over 25 years, reproductive success of early breeders increased by 42%, producing a steeper seasonal decline in reproductive success. The difference between the laying date producing highest reproductive success and the median laying date of the population increased, which suggests an increase in the selection pressure for that trait. Observed clutch size was lower than clutch size yielding the highest reproductive success for most laying dates. However, at the individual level, clutch size could still be optimal if the additional time required to acquire nutrients to lay extra eggs is compensated by a reduction in reproductive success due to a delayed laying date. Nonetheless, breeding phenology may not respond sufficiently to meet future environmental changes induced by warming temperatures.



2007 ◽  
Vol 85 (1) ◽  
pp. 56-62 ◽  
Author(s):  
Peter J. Harmata ◽  
Marco Restani ◽  
Alan R. Harmata

In 1998 and 1999, we determined the spatial distribution, foraging behavior, and reproductive success of ospreys ( Pandion haliaetus (L., 1758)) nesting along the upper Missouri River, Montana. We combined our data with that collected in the same area in 1981–1982 and 1990–1991 to investigate factors influencing settlement patterns. The study area was composed of four distinct habitats, three reservoirs and one free-flowing river section. Although number of occupied nests on each habitat increased from 1981–1982 to 1998–1999, the greatest percentage increases in nest density occurred on habitats previously hypothesized to contain the least prey. Osprey reproductive success was positively related to foraging rates, which differed across habitats, being highest on reservoirs and lowest on the free-flowing river. However, reproductive success was adequate for replacement on each habitat. Most fish consumed by ospreys on each habitat were suckers (Catostomidae), followed by salmonids and cyprinids. Fish density, determined from gill netting, was highest on the largest and shallowest reservoir. Over two decades, ospreys shifted their relative spatial use of the upper Missouri River such that reservoirs were occupied first and the free-flowing river section was occupied last. The degree to which presence of conspecifics, distribution of nest trees and prey, and dispersal affected settlement patterns probably varied by spatial scale.



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