Clutch size in eastern phoebes (Sayornis phoebe) II: age effects and seasonal variation

1993 ◽  
Vol 71 (9) ◽  
pp. 1738-1742 ◽  
Author(s):  
Kelvin F. Conrad ◽  
Raleigh J. Robertson
Keyword(s):  
Seasonal Variation ◽  
Clutch Size ◽  
Egg Production ◽  
Age Classes ◽  
Female Age ◽  
Linear Decrease ◽  
Double Brooding ◽  
Second Year ◽  
Pattern Of Variation ◽  
Seasonal Decline

We examined seasonal variation in clutch size among single- and double-brooding eastern phoebes to learn how the pattern of variation among female age-classes and early and late-season breeders contributed to overall seasonal variation in clutch size. Clutch sizes of eastern phoebes did not decline predictably (linearly or quadratically) with season when we considered all clutches laid over the season, nor when the first and second clutches of double-brooding birds were each regarded separately. Total seasonal egg production by double-brooding second-year (SY) females declined linearly with season but that of after-second-year (ASY) females did not. Among single-brooding females, which were nearly all SY birds, clutch size, and hence total seasonal egg production, were unaffected by season. In general, SY birds bred later, laid fewer eggs, and were less likely to double-brood than ASY birds. The large seasonal variation in clutch size for the entire population was influenced by two different groups of SY females: (1) double-brooding SY females that nested at the same time as double-brooding ASY birds and had similar clutch sizes, but showed a linear decrease in total seasonal egg production versus initiation date, and (2) single-brooding SY females that nested after double-brooding females, had clutch sizes similar to double-brooding females, and showed no linear decrease in total seasonal egg production versus initiation date. Combined with double-brooding ASY females, these two groups of SY birds increase the variation in clutch size observed on any given day and obscure the pattern of seasonal decline commonly reported for other species.

scholarly journals Covariation of Clutch Size, Laying Date, and Incubation Tendency in the American Kestrel

The Condor ◽  
2001 ◽  
Vol 103 (3) ◽  
pp. 570-578 ◽  
Author(s):  
Keith W. Sockman ◽  
Hubert Schwabl
Keyword(s):  
Environmental Factors ◽  
Clutch Size ◽  
Egg Production ◽  
Laying Date ◽  
Falco Sparverius ◽  
Free Living ◽  
American Kestrel ◽  
Proximate Mechanisms ◽  
American Kestrels ◽  
Seasonal Decline

Abstract Seasonal decline in clutch size is common in birds, but the proximate mechanisms for this phenomenon have not been elucidated. The most credible model to date posits that late-laying females lay fewer eggs due to a seasonal increase in the tendency to incubate during laying, which inhibits egg production. We tested this model with free-living and laboratory American Kestrels (Falco sparverius) by quantifying changes in clutch size and incubation tendency during laying over the course of the breeding phase. Consistent with the model, clutch size in free-living kestrels decreased while incubation increased with progress of the 74-day breeding phase. Inconsistent with the model, variation in incubation tendency during laying was not associated with clutch size in either the field or the laboratory. In the laboratory, incubation increased but clutch size did not decrease over the course of the 77-day breeding phase. In the laboratory, females that nested early in one breeding phase renested more quickly and nested in a second breeding phase more quickly than females nesting late in the first breeding phase. This indicates that timing of laying is, in part, a property of individual females, independent of environmental factors. Together, our findings suggest that both clutch size and timing of laying are inherent, correlated properties of particular females. Although incubation tendency may influence clutch size, other factors appear to override its influence. Covariación del Tamaño de la Nidada, la Fecha de Postura y la Tendencia de Incubación en Falco sparverius Resumen. Aunque la disminución estacional en el tamaño de la nidada es común entre las aves, los mecanismos proximales para este fenómeno no han sido elucidados. El modelo de mayor credibilidad propuesto hasta el momento sugiere que las hembras que ovipositan tarde ponen menos huevos debido a un aumento estacional en la tendencia a incubar durante la postura que inhibe la producción de huevos. Pusimos a prueba este modelo con individuos de Falco sparverius en condiciones naturales y en cautiverio, cuantificando los cambios en el tamaño de la nidada y la tendencia a incubar durante la postura a lo largo de la época reproductiva. Tal como el modelo plantea, el tamaño de la nidada en individuos silvestres de F. sparverius disminuyó mientras que la incubación aumentó a medida que transcurrían los 74 días de la época de reproducción. Mientras tanto, en contraste con el modelo, la variación en la tendencia a incubar durante la postura no estuvo asociada con el tamaño de la nidada ni en el campo ni en el laboratorio. En el laboratorio, la incubación aumentó pero el tamaño de la nidada no disminuyó en el transcurso de la época reproductiva (77 días). En condiciones de laboratorio, las hembras que anidaron temprano en una fase reproductiva volvieron a anidar más rápidamente en una segunda fase que las hembras que anidaron tarde en la primera. Esto indica que el tiempo en que se hace la postura es en parte una propiedad de cada hembra y es independiente de factores ambientales. En conjunto, nuestros hallazgos sugieren que tanto el tamaño de la nidada como el momento de la postura son propiedades correlacionadas de cada hembra en particular. Aunque la tendencia a incubar podría influenciar el tamaño de la nidada, otros factores parecen anular su influencia.

Within-season and age-related patterns of reproductive performance in female tree swallows (Tachycineta bicolor)

1988 ◽  
Vol 66 (4) ◽  
pp. 827-834 ◽  
Author(s):  
Bridget J. Stutchbury ◽  
Raleigh J. Robertson
Keyword(s):  
Clutch Size ◽  
Breeding Season ◽  
Reproductive Performance ◽  
Tachycineta Bicolor ◽  
Foraging Efficiency ◽  
Tree Swallows ◽  
Age Classes ◽  
Age Related ◽  
Female Tree ◽  
Second Year

In many species of birds, clutch size decreases as the season progresses, but this is confounded by the fact that young birds not only often have smaller clutches but also breed later than older females. We examined the effect of time of season on clutch size, hatching success, and fledging success of female tree swallows (Tachycineta bicolor) in their second year (SY) and after their second year (ASY), and compared their reproductive performance while controlling for time of season. For both SY and ASY females, clutch size decreased significantly with later first egg dates, which caused number hatched and number fledged per brood to also decline as the season progressed. However, neither the proportion of eggs hatched nor the proportion of young fledged was correlated with first egg date. The within-season decline in clutch size was not due simply to replacement clutches or female age, and we argue that it is also not due to a decrease in food abundance over the breeding season. Age-related differences in reproductive success depended on the time of season. Early in the breeding season, ASY females were superior to SY females in every measure of reproductive performance; however, there were no significant differences between age-classes late in the season. ASY females were more successful than SY females in raising clutches of five or six eggs, which were most common early in the season, but there was no difference between age-classes in raising clutches of four eggs. We suggest that an age-related difference in foraging efficiency and within-season changes in the cost of competition could explain this pattern.

scholarly journals Temporal changes in reproductive success and optimal breeding decisions in a long-distance migratory bird

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Cynthia Reséndiz-Infante ◽  
Gilles Gauthier
Keyword(s):  
Reproductive Success ◽  
Clutch Size ◽  
Environmental Changes ◽  
Migratory Bird ◽  
Laying Date ◽  
Negative Consequences ◽  
Breeding Phenology ◽  
Additional Time ◽  
Long Distance ◽  
Seasonal Decline

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.

scholarly journals Nutrient Reserves and Clutch-Size Regulation of Northern Shovelers in Alaska

The Auk ◽  
2000 ◽  
Vol 117 (4) ◽  
pp. 971-979 ◽  
Author(s):  
Margaret C. MacCluskie ◽  
James S. Sedinger
Keyword(s):  
Clutch Size ◽  
Egg Production ◽  
Prairie Pothole Region ◽  
Prairie Pothole ◽  
High Productivity ◽  
Brood Rearing ◽  
Nutrient Reserve ◽  
Anas Clypeata ◽  
Nutrient Reserves ◽  
Nest Initiation

Abstract We determined patterns of nutrient-reserve use by female Northern Shovelers (Anas clypeata) nesting at Minto Flats, Alaska, and compared them with those of female shovelers nesting in the Prairie Pothole Region of Manitoba, Canada. Individual variation in somatic lipid was best explained by nest initiation date; females that initiated nests early had larger lipid reserves than females that delayed nest initiation. These results contrast with those from Manitoba, which showed that females used lipid reserves and stored protein during egg production. Incubating females from Alaska did not use protein or mineral reserves, but lipid reserves decreased significantly throughout incubation. Females in Alaska and Manitoba used lipid reserves similarly during incubation. We conclude that endogenous nutrient availability does not proximately limit clutch size during laying for this population of shovelers, possibly due to the high productivity of wetlands in interior Alaska and/or the long photoperiod that allow females to forage extensively. Successful completion of incubation or brood rearing may be an ultimate factor that controls clutch size for this population of shovelers.

The influence of familiarity, age, experience and female mate choice on pregnancies in captive grey mouse lemurs

Behaviour ◽  
2003 ◽  
Vol 140 (3) ◽  
pp. 301-318 ◽  
Author(s):  
Elke Zimmermann ◽  
Ute Radespiel
Keyword(s):  
Mate Choice ◽  
Female Mate Choice ◽  
Female Dominance ◽  
Age Classes ◽  
Female Age ◽  
Female Mate ◽  
Sexual Behaviours ◽  
Mouse Lemurs ◽  
Reduced Rate ◽  
Old Females

AbstractConceptions in mammals may depend on a variety of factors including mate familiarity, age, sociosexual experience and female mate choice. We tested predictions for the effects of these factors on pregnancies in a captive colony of grey mouse lemurs (Microcebus murinus). The succession of oestrous cycles and pregnancies was analysed for a total of 26 different females that were housed together with 33 different males over a total of 124 oestrous cycles between 1995 and 2001. In addition, sexual behaviours were recorded and analysed over 13 oestrous cycles of 9 different females. An effect of mate familiarity on pregnancies could be detected by a frequent delay of pregnancies to the second cycle of the season (66.7% of the possible cases). Female age influenced pregnancies as the 2-3-year old females were less likely to become pregnant than females of other age classes. This reduced rate of pregnancies, however, was probably due to the lack of previous sociosexual experience with males. Females that have not been housed with males within their first reproductive season, needed one or two years of sociosexual experience before their first successful impregnation. These findings are discussed as a side effect of the ontogenetic development of female dominance. Female mate choice could be deduced from the succession of pregnancies and the strong responsibility of the females for the termination of matings.

scholarly journals Patterns and predictors of food texture introduction in French children aged 4–36 months

2018 ◽  
Vol 120 (9) ◽  
pp. 1065-1077 ◽  
Author(s):  
Lauriane Demonteil ◽  
Eléa Ksiazek ◽  
Agnès Marduel ◽  
Marion Dusoulier ◽  
Hugo Weenen ◽  
...  
Keyword(s):  
Complementary Feeding ◽  
Eating Habits ◽  
First Year ◽  
Age Classes ◽  
Cross Sectional Survey ◽  
Cross Sectional ◽  
Food Texture ◽  
Second Year ◽  
Almost All ◽  
Linear Regressions

AbstractThe aims of this study were to describe which and when food textures are offered to children between 4 and 36 months in France and to identify the associated factors. An online cross-sectional survey was designed, including questions about 188 food texture combinations representing three texture levels: purées (T1), soft small pieces (T2) and hard/large pieces and double textures (T3). Mothers indicated which combinations they already offered to their child. A food texture exposure score (TextExp) was calculated for all of the texture levels combined and for each texture level separately. Associations between TextExp and maternal and child characteristics and feeding practices were explored by multiple linear regressions, per age class. Answers from 2999 mothers living in France, mostly educated and primiparous, were analysed. Over the first year, children were mainly exposed to purées. Soft and small pieces were slowly introduced between 6 and 22 months, whereas hard/large pieces were mainly introduced from 13 months onwards. TextExp was positively associated with children’s number of teeth and ability to eat alone with their finger or a fork. For almost all age classes, TextExp was higher in children introduced to complementary feeding earlier, lower for children who were offered only commercial baby foods and higher for those who were offered only home-made/non-specific foods during the second year. Our study shows that until 12 months of age the majority of French children were exposed to pieces to a small extent. It provides new insights to further understand the development of texture acceptance during a key period for the development of eating habits.

scholarly journals Seasonal variation in the egg morphology of the copepod Eurytemora americana and its relationship with reproductive strategy in a temperate estuary in Argentina

2012 ◽  
Vol 69 (3) ◽  
pp. 380-388 ◽  
Author(s):  
Anabela A. Berasategui ◽  
Mónica S. Hoffmeyer ◽  
M. Sofía Dutto ◽  
Florencia Biancalana
Keyword(s):  
Electron Microscopy ◽  
Seasonal Variation ◽  
Reproductive Strategy ◽  
Egg Production ◽  
Resting Eggs ◽  
Bahía Blanca Estuary ◽  
Temperate Estuary ◽  
Egg Carrying ◽  
Egg Morphology ◽  
Eurytemora Americana

Abstract Berasategui, A. A., Hoffmeyer, M. S., Dutto, M. S., and Biancalana, F. 2012. Seasonal variation in the egg morphology of the copepod Eurytemora americana and its relationship with reproductive strategy in a temperate estuary in Argentina. – ICES Journal of Marine Science, 69: 380–388. Seasonal variation in the morphology of Eurytemora americana eggs and its relationship with reproductive strategy were studied in the Bahía Blanca Estuary. Eggs from field females were analysed morphologically by optical (OM) and electron microscopy [scanning electron microscopy (SEM)–transmission electron microscopy (TEM)] during the population pulse. Additionally, egg-carrying females were incubated simulating in situ environmental conditions to evaluate the resting egg character. Subitaneous and resting eggs were indistinguishable by OM, but showed different chorion appearance under SEM and TEM. Sinuous patterned chorion eggs, mainly produced during the period of population growth, were classed as subitaneous eggs based on their high level of hatching success. Eggs with a sponge-like appearance, produced after the population peaked, were classed as diapause eggs based on their inability to hatch even under favourable conditions. There were significant differences in egg size through the population pulse and diapause eggs were significantly bigger than subitaneous eggs. The observation of both morphotypes in egg-carrying females after peak population abundance confirms the existence of a transitional reproductive stage before the exclusive production of diapause eggs at the end of the pulse. Diapause egg production enables E. americana to resist adverse conditions, ensuring its survival in temperate estuaries.

Host age and the growth and fecundity of Hymenolepis diminuta in the rat

1988 ◽  
Vol 62 (2) ◽  
pp. 158-162 ◽  
Author(s):  
R. J. Quinnell
Keyword(s):  
Egg Production ◽  
Wistar Rats ◽  
Dry Weight ◽  
Hymenolepis Diminuta ◽  
Crowding Effect ◽  
Age Classes ◽  
Immunological Mechanisms ◽  
Worm Recovery ◽  
Male Wistar Rats ◽  
Old Rats

ABSTRACTFive, 20, and 80 cysticercoid infections of Hymenolepis diminuta were established in 1-, 2- and 5-month-old male Wistar rats. Worm numbers, dry weights and egg outputs were determined on day 28 post infection. Worm recovery was found to be independent of cysticercoid dose in 1-month-old rats, but density-dependent in older rats. Density dependence affected both worm dry weight and egg production in all 3 age classes of host studied. However, at the highest dose both dry weight and egg production were significantly decreased in 2- and 5-month-old rats compared with 1-month-old rats. The results cannot be explained solely in terms of competition for a resource, and suggest that immunological mechanisms may have an important role in the “crowding effect”.

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