Influence of forced renesting, seasonal date of laying, and female characteristics on clutch size and egg traits in captive American Kestrels

1982 ◽  
Vol 60 (1) ◽  
pp. 71-79 ◽  
Author(s):  
David M. Bird ◽  
Paul C. Laguë
Keyword(s):  
Clutch Size ◽  
Eggshell Thickness ◽  
Falco Sparverius ◽  
Egg Weight ◽  
American Kestrels ◽  
First Clutch ◽  
Egg Traits

Of 78 nesting attempts by captive American Kestrels (Falco sparverius) between 1974 and 1977, 95% successfully renested after removal of the first clutch. Replacement clutches had fewer eggs, longer eggs, and eggs with thicker shells than first clutches. Clutch size, egg length, eggshell thickness, and fresh egg weight declined seasonally. Renesting intervals were shorter in older, experienced layers and clutch size increased by 0.20 eggs with each additional year of age.

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.

Reproductive performance of American Kestrels laying replacement clutches

1985 ◽  
Vol 63 (11) ◽  
pp. 2590-2593 ◽  
Author(s):  
Reed Bowman ◽  
David M. Bird
Keyword(s):  
Reproductive Success ◽  
Reproductive Performance ◽  
Falco Sparverius ◽  
Nestling Growth ◽  
Fledging Success ◽  
American Kestrels ◽  
First Clutch ◽  
Second Clutch

Egg dimensions, nestling growth, and reproductive success were compared between first and second clutch nests of American Kestrels (Falco sparverius) to determine the influence of renesting on fledging success. Eggs were removed from 11 nests during 1982–1983. Eight nests served as controls. Most pairs (81.8%) renested on their original territory. We found no significant differences in egg dimensions, fertility, or hatchability between the two groups. Second clutch males (n = 6 clutches) were smaller at hatching than males from first clutches (n = 8 clutches). By day 24 these males (n = 5 clutches) were heavier, with significantly longer manus and antebrachia than first clutch males (n = 3 clutches). However, five of eight first clutch nests fledged all males before day 24. Males remaining in first clutch nests beyond day 24 were lighter with significantly smaller antebrachia by day 18 than males fledging before day 24. This may have biased our comparisons between first and second clutch males. No significant differences in growth were found between female groups. First-clutch progeny fledged significantly younger than second-clutch birds. Males fledged earlier than females in first clutches, but the sexes fledged simultaneously in second clutches.

Nestling growth and fledging success in manipulated American kestrel broods

1992 ◽  
Vol 70 (12) ◽  
pp. 2421-2425 ◽  
Author(s):  
Nicholas W. Gard ◽  
David M. Bird
Keyword(s):  
Clutch Size ◽  
Growth Rates ◽  
Brood Size ◽  
Wild Birds ◽  
Falco Sparverius ◽  
Nestling Growth ◽  
American Kestrel ◽  
Fledging Success ◽  
American Kestrels ◽  
Parental Ability

To study factors regulating clutch size in American Kestrels (Falco sparverius), brood manipulation experiments were performed on captive and wild birds in southwestern Quebec during 1986 and 1987. The largest normally occurring brood size was 5 young. Manipulations enlarged or decreased broods to 7 or 2 young, respectively. Significantly more young fledged from wild control and enlarged broods in 1987 than from comparable groups in 1986. The average number of young fledging from enlarged wild broods in 1987 was slightly higher than for control broods, but fledging weight was significantly depressed in enlarged broods. Growth rates and tarsal and antebrachial length at fledging were not affected by brood size, but development of primary feathers was slower in enlarged wild broods. Parental ability to adequately feed all young appears to be the major factor limiting brood size in American Kestrels.

Fertility, egg weight loss, hatchability, and fledging success in replacement clutches of captive American Kestrels

1982 ◽  
Vol 60 (1) ◽  
pp. 80-88 ◽  
Author(s):  
David M. Bird ◽  
Paul C. Laguë
Keyword(s):  
Weight Loss ◽  
Falco Sparverius ◽  
Egg Weight ◽  
Fledging Success ◽  
American Kestrels ◽  
Artificial Incubation

From 1974 to 1977, 78 pairs of captive American Kestrels (Falco sparverius) were induced to lay replacement clutches by removal and artificial incubation of their first clutches. No significant differences existed between first and replacement clutches for fertility, hatchability, and fledging success. Hatchability, as well as fledging success of young, did not differ significantly between artificially and naturally incubated eggs. Both fertility and hatchability declined with eggs laid later in the season.

Reproductive changes in American kestrels (Falco sparverius) in relation to exposure to technical hexabromocyclododecane flame retardant

2011 ◽  
Vol 30 (11) ◽  
pp. 2570-2575 ◽  
Author(s):  
Kim J. Fernie ◽  
Sarah C. Marteinson ◽  
David M. Bird ◽  
Ian J. Ritchie ◽  
Robert J. Letcher
Keyword(s):  
Flame Retardant ◽  
Falco Sparverius ◽  
American Kestrels

The influence of Trichinella pseudospiralis infection on the behaviour of captive, nonbreeding American kestrels (Falco sparverius)

1988 ◽  
Vol 66 (7) ◽  
pp. 1685-1692 ◽  
Author(s):  
Michèle D. Saumier ◽  
Manfred E. Rau ◽  
David M. Bird
Keyword(s):  
Falco Sparverius ◽  
Competitive Fitness ◽  
American Kestrel ◽  
Behavioural Changes ◽  
Trichinella Pseudospiralis ◽  
Behavioural Effects ◽  
American Kestrels ◽  
Muscle Larvae ◽  
Adult Phase ◽  
Muscle Groups

Trichinella pseudospiralis infections induced mild behavioural changes in the American kestrel host (Falco sparverius) within the first 5 days postinoculation, a period that corresponds to the adult phase of the infection. However, more severe effects on mobility were precipitated as the larvae migrated and became established in the musculature. The debilitation persisted for at least 5 weeks postinoculation and involved a reduction in exercising, flying, elevated perching, and preening, and was accompanied by an increase in the frequency of walking and floor perching. Such behavioural effects, attributable to the presence of muscle larvae, may reduce the competitive fitness of infected individuals. The muscle larvae were randomly distributed among various muscle groups.

Sign in / Sign up

Export Citation Format

Share Document