Factors Influencing Age-Related Reproductive Success in the Willow Ptarmigan

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.

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.


1986 ◽  
Vol 64 (9) ◽  
pp. 1926-1929 ◽  
Author(s):  
Susan E. Cosens ◽  
Spencer G. Sealy

Songs of male yellow warblers (Dendroica petechia), ranging from 1 to 6 years of age, were recorded in the spring and summer of 1984. Recorded repertoire size and number of songs shared with neighbours varied positively with age in the spring but not in summer. Neither clutch initiation date nor fledging success varied with age or number of songs shared but both measures of reproductive success varied with size of recorded song repertoire.


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.


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.


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.


2013 ◽  
Vol 91 (8) ◽  
pp. 581-588 ◽  
Author(s):  
Nicola Banger ◽  
Gabriel Blouin-Demers ◽  
Grégory Bulté ◽  
Stephen C. Lougheed

Sexual selection theory predicts that males should be promiscuous to maximize their reproductive success, while females should be choosy. Yet females of many taxa often produce progeny sired by multiple males, indicating that promiscuity can be important for the reproductive success of females. Promiscuity may enhance the fitness of females if it increases the genetic quality, or the genetic variety, and thus the viability of their offspring. We quantified the number of sires per clutch in a population of Northern Map Turtles (Graptemys geographica (LeSueur, 1817)) in Lake Opinicon, Ontario, Canada, and tested whether the number of sires affects several metrics of viability in hatchlings. Based on the most conservative estimate, at least 71% of clutches in this population are sired by multiple males, but there was no evidence that larger clutches are sired by more males. Clutches sired by more males had higher hatching success and survival, but the differences were not statistically significant. We did not find any effect of the number of sires on hatchling morphology or locomotor performance. Collectively, our results partially support the hypothesis that promiscuity can increase the reproductive success of female Northern Map Turtles.


2021 ◽  
Vol 133 (1) ◽  
pp. 135-142
Author(s):  
Marion Cheron ◽  
Frédéric Angelier ◽  
Cécile Ribout ◽  
François Brischoux

Abstract Reproductive success is often related to parental quality, a parameter expressed through various traits, such as site selection, mate selection and energetic investment in the eggs or progeny. Owing to the complex interactions between environmental and parental characteristics occurring at various stages of the reproductive event, it is often complicated to tease apart the relative contributions of these different factors to reproductive success. Study systems where these complex interactions are simplified (e.g. absence of parental care) can help us to understand how metrics of parental quality (e.g. gamete and egg quality) influence reproductive success. Using such a study system in a common garden experiment, we investigated the relationships between clutch hatching success (a proxy of clutch quality) and offspring quality in an amphibian species lacking post-oviposition parental care. We found a relationship between clutch quality and embryonic development duration and hatchling phenotype. We found that hatchling telomere length was linked to hatching success. These results suggest that clutch quality is linked to early life traits in larval amphibians and that deciphering the influence of parental traits on the patterns we detected is a promising avenue of research.


2019 ◽  
Vol 76 (7) ◽  
pp. 1147-1160 ◽  
Author(s):  
Kari J. Dammerman ◽  
Molly A.H. Webb ◽  
Kim T. Scribner

Abiotic conditions and demographic factors can influence the timing of spawning. Behavioral plasticity allows females to select spawning conditions that are conducive to offspring development; however, reproductive costs associated with delaying spawning are not well understood. In this study, factors influencing timing of female spawning, residence time (RT), and reproductive success (RS) during two seasons were determined, and plasma testosterone concentrations were used to quantify atretic rates in a wild, lake sturgeon (Acipenser fulvescens) population. For the 123 females monitored, RT ranged from 1 to 23 days and was influenced by arrival date, temperature, discharge, and male number, with the latter having the largest influence. RS varied due to arrival date, temperature, discharge, male number, male length, and operational sex ratio. Two females had testosterone levels indicative of atresia and RS estimates lower than yearly means; however, most females had normal ovaries, suggesting little reproductive costs of plasticity in spawning ground residency time. Results demonstrate the multitude of factors influencing female reproductive behavior and RS, highlighting the importance of abiotic and demographic conditions to recruitment in wild populations.


Sign in / Sign up

Export Citation Format

Share Document