Time, Condition, and the Seasonal Decline of Avian Clutch Size

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.

Family Planning in the Kestrel (Falco Tinnunculus): the Proximate Control of Covariation of Laying Date and Clutch Size

Behaviour ◽

10.1163/156853990x00077 ◽

1990 ◽

Vol 114 (1-4) ◽

pp. 117-136 ◽

Cited By ~ 150

Author(s):

Serge Daan ◽

Michael Hall ◽

Theo Meijer

Keyword(s):

Clutch Size ◽

Feedback Loop ◽

Significant Advance ◽

Laying Date ◽

Plasma Prolactin ◽

Free Living ◽

Feeding Experiments ◽

Incubation Behaviour ◽

Time Of Year ◽

Seasonal Decline

AbstractThe time in spring when a male kestrel rapidly increases his daily hunting time and his hunting yield, and thereby the amount of food delivered to the female, determines the date when she lays the first egg. Food experiments in free-living and captive kestrels gave a significant advance in laying date. Clutch size, which decreases with progressive laying date, did not change independent of date in response to food manipulation. These effects are in agreement with most other feeding experiments. Photoperiod experiments in kestrels advanced the reproductive cycle in constant long days, and a similar seasonal decline in clutch size was found. It seems that there is an internally preprogrammed decrease in clutch size within an annual "reproductive window". A proximate control model for the seasonal decline of clutch size is proposed, modified from an earlier model by HAFTORN (1985). This incorporates an increasing tendency to incubate the first eggs with progression of the season, an egg contact-incubation positive feedback loop, and the resorption of further follicles in the ovary when the laying female incubates 50% of the time. This follicle resorption fixes the clutch size ca. four days before the last egg is laid. the 50% incubation level is reached earlier in late females and consequently resorption starts earlier and the resulting clutch is smaller than in early females. Experiments in kestrels with removal and addition of eggs, in combination with measurements of incubation behaviour are discussed in relation to the model. Plasma prolactin data of female kestrels show that this hormone is a serious candidate for a physiological component relaying time of year in our model for clutch size regulation.

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

The Condor ◽

10.1093/condor/103.3.570 ◽

2001 ◽

Vol 103 (3) ◽

pp. 570-578 ◽

Cited By ~ 2

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.

Cyclic variation in seasonal recruitment and the evolution of the seasonal decline in Ural owl clutch size

Proceedings of The Royal Society B Biological Sciences ◽

10.1098/rspb.2001.1929 ◽

2002 ◽

Vol 269 (1491) ◽

pp. 647-654 ◽

Cited By ~ 12

Author(s):

Jon E Brommer ◽

Hannu Pietiäinen ◽

Hanna Kokko

Keyword(s):

Clutch Size ◽

Cyclic Variation ◽

Seasonal Decline ◽

Ural Owl

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

Canadian Journal of Zoology ◽

10.1139/z93-246 ◽

1993 ◽

Vol 71 (9) ◽

pp. 1738-1742 ◽

Cited By ~ 5

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.

Seasonal Decline in Clutch Size of the Barnacle Goose in Svalbard

The Condor ◽

10.2307/1369506 ◽

1996 ◽

Vol 98 (1) ◽

pp. 42-47 ◽

Cited By ~ 26

Author(s):

Laila Dalhaug ◽

Ingunn M. Tombre ◽

Kjell Einar Erikstad

Keyword(s):

Clutch Size ◽

Barnacle Goose ◽

Seasonal Decline

Clutch Size of Kestrels: Seasonal Decline and Experimental Evidence for Food Limitation under Fluctuating Food Conditions

Oikos ◽

10.2307/3546837 ◽

1998 ◽

Vol 83 (2) ◽

pp. 259 ◽

Cited By ~ 96

Author(s):

Erkki Korpimäki ◽

Jürgen Wiehn ◽

Erkki Korpimaki ◽

Jurgen Wiehn

Keyword(s):

Experimental Evidence ◽

Clutch Size ◽

Food Limitation ◽

Food Conditions ◽

Seasonal Decline

Seasonal decline in clutch size in European starlings: a novel randomization test to distinguish between the timing and quality hypotheses

Journal of Animal Ecology ◽

10.1046/j.0021-8790.2001.00566.x ◽

2001 ◽

Vol 70 (6) ◽

pp. 1080-1087 ◽

Cited By ~ 62

Author(s):

Julian K. Christians ◽

Melissa Evanson ◽

Jonathan J. Aiken

Keyword(s):

Clutch Size ◽

Randomization Test ◽

European Starlings ◽

Seasonal Decline

Intra-seasonal decline of clutch size in Lesser Snow Geese

Oecologia ◽

10.1007/bf00378243 ◽

1989 ◽

Vol 79 (1) ◽

pp. 83-90 ◽

Cited By ~ 28

Author(s):

Jean Hamann ◽

Fred Cooke

Keyword(s):

Clutch Size ◽

Snow Geese ◽

Lesser Snow Geese ◽

Seasonal Decline

The Seasonal Decline in Clutch Size: An Experiment with Supplementary Food in the Kestrel, Falco tinnunculus

Oikos ◽

10.2307/3545833 ◽

1994 ◽

Vol 71 (3) ◽

pp. 451 ◽

Cited By ~ 41

Author(s):

José Miguel Aparicio ◽

Jose Miguel Aparicio

Keyword(s):

Clutch Size ◽

Falco Tinnunculus ◽

Supplementary Food ◽

Seasonal Decline