Variation in incubation length and hatching asynchrony in Eastern Kingbirds: Weather eclipses female effects

The Auk ◽  
2021 ◽  
Author(s):  
Samantha M Gillette ◽  
Amanda L Klehr ◽  
Michael T Murphy

Abstract Incubation length and hatching asynchrony are integral elements of the evolved reproductive strategies of birds. We examined intra- and interpopulation variation in both traits for Eastern Kingbird (Tyrannus tyrannus) populations from New York (NY), Kansas (KS), and Oregon (OR) and found that both incubation length and hatching asynchrony were not repeatable among females, after controlling for a repeatable trait, clutch size. Instead, incubation length and clutch size were influenced by ambient temperature and precipitation. Incubation length exhibited the same median (15 days) and range (13–17 days) at all sites. Model selection results indicated that incubation periods for the smallest and largest clutches were longer in NY than KS when rain was frequent throughout incubation, in replacement nests, and likely when ambient temperatures were low during egg-laying. Full hatching usually required 2 days (but up to 3), with synchronous hatching associated with small clutch sizes, short incubation periods, frequent rain during the egg-laying period, and low ambient temperatures during the first half of incubation. Nestling starvation was uncommon (5–9% of nestlings monitored) and not associated with greater hatching asynchrony. These results indicate that while clutch size, a repeatable female trait, contributed to variation in incubation length and hatching asynchrony in Eastern Kingbirds, weather was a greater source of variation, especially for incubation length.

1995 ◽  
Vol 73 (9) ◽  
pp. 1579-1587 ◽  
Author(s):  
Gregory J. Robertson

Annual variation in volumes of eggs laid by common eiders (Somateria mollissima sedentaria) nesting at La Pérouse Bay, Manitoba (58°43′N, 93°27′W), was studied over 3 years (1991–1993). Temperatures during the egg-laying period were higher in 1991 than in 1992 and 1993. However, the eiders began nesting in 1993 at the same time as in 1991, whereas in 1992 the eiders began laying approximately 2 weeks later. Eiders laid significantly smaller clutches in 1992 than in the other 2 years. Egg size did not correlate with clutch size or laying date in any year. However, eiders laid smaller eggs in 1992 and 1993 than in 1991. In five egg clutches, the pattern of intraclutch egg-size variation was different among years. The last laid eggs of five egg clutches were disproportionately smaller in 1992 and 1993 (cold years) than those laid in 1991. Minimum daily temperatures before the egg-laying period (during rapid yolk development) were positively correlated with egg size. However, this effect was not significant when year and egg sequence were controlled for. Egg-size variation was correlated with the overall ambient temperatures during the laying period, whereas annual clutch-size variation was correlated with laying date, suggesting that the proximate mechanisms affecting clutch and egg size are different.


The Condor ◽  
2001 ◽  
Vol 103 (4) ◽  
pp. 845-851 ◽  
Author(s):  
Diane L. Rowe ◽  
Michael T. Murphy ◽  
Robert C. Fleischer ◽  
Paul G. Wolf

Abstract Genetic parentage in the socially monogamous and territorial Eastern Kingbird (Tyrannus tyrannus) was examined in a central New York population by multilocus DNA fingerprinting. Extra-pair young were identified in 60% (12 of 20) of nests. Of the 64 nestlings profiled, 42% were sired by extra-pair males, but no cases of conspecific brood parasitism were detected. These results are markedly different from a previous electrophoretic study of the same species in a Michigan population, which reported 39% of nestlings were unrelated to one (typically the mother, quasiparasitism) or both (conspecific brood parasitism) of the putative parents. In the New York population, extra-pair paternity was most common among females that returned to breed on a former territory. Among females that were new to a breeding territory, extra-pair paternity increased directly with breeding density. Although the power of the tests was low, neither breeding synchrony nor male experience with a breeding territory appeared to be associated with the occurrence of extra-pair young. Alta Frecuencia de Paternidad Extra-Pareja en Tyrannus tyrannus Resumen. Se examinó la paternidad genética de Tyrannus tyrannus, especie socialmente monógama y territorial, mediante la técnica de huellas dactilares genéticas de múltiples loci en una población de Nueva York central. En el 60% (12 de 20) de los nidos se identificaron juveniles con origen extra-pareja. De los 64 pichones investigados, el 42% fue engendrado por machos fuera de la pareja, aunque no se detectaron nidadas con parasitismo conespecífico. Estos resultados son considerablemente diferentes a los obtenidos en un estudio previo para la misma especie en una población de Michigan, el cual reportó que el 39% de los pichones no estaban relacionados con uno (tipicamente a la madre, cuasiparasitismo) o ambos (parasitismo de nido conespecífico) padres putativos. En la población de Nueva York, la paternidad extra-pareja fue más común entre hembras que retornaron a criar a territorios que habían ocupado previamente. Entre las hembras que ocuparon por primera vez un territorio de cría, la paternidad extra-pareja aumentó directamente con la densidad de individuos reproductivos. A pesar que el poder del análisis fue bajo, ni la sincronía reproductiva, ni la experiencia de los machos en sus territorios de cria, parecen estar asociados a la ocurrencia de juveniles extra-pareja.


2015 ◽  
Vol 39 (1) ◽  
pp. 4-23
Author(s):  
Piotr Kamiński ◽  
Leszek Jerzak ◽  
Joerg Boehner

Abstract A Jackdaw colony of over 200 nests, built in cavities of old willow trees along 3 km of a small road running through meadows next to the river Narew in an agricultural landscape (15 km southwest of Białystok, NE Poland), was studied to determine nest locations and construction, onset of egg laying, incubation period, egg parameters, clutch size and hatching success, nestling growth and mortality, breeding success as well as predation. The onset of laying and clutch size were correlated with ambient temperature and precipitation (p < 0.001). Hatching success was also determined by these environmental factors as well as by the degree of predation (p < 0,001). There was a statistically significant correlation between clutch size and hatching success (p < 0.001) as well as fledging success (p < 0.001). Nestlings hatching first or second grew faster, reached a higher body weight, and had a lower mortality rate than those hatching last or second to last. There was also a statistically significant correlation between nestling survival and clutch size as well as ambient temperature (p < 0.001 each). Nestling mortality caused by predators, i. e. mainly by martens Martes foina and domestic cats Felis domestica, was high in periods of intensive burning of the meadows surrounding the Jackdaw colony. However, mortality rate of the youngest nestlings was almost 100% lower in periods of high predation compared to times of low predatory activity. Several groups of insects constituted a high amount of nestling food, e. g. 60% of all Orthoptera occurring in the meadows next to the breeding colony. In that area the total dry body mass of phytophagous invertebrates amounted to 1.4-2.0 g per m2, of which 0.3 g were fed to the nestlings. The percentage of zoophagous invertebrates delivered to the offspring was high with about 30-35%. From an economical point of view, Jackdaws during the breeding season are advantageous in an agricultural landscape because they reduce pest insects significantly while consuming only an insignificant amount of all seeds applied.


The Auk ◽  
2007 ◽  
Vol 124 (3) ◽  
pp. 1010-1022 ◽  
Author(s):  
Michael T. Murphy

AbstractI report on the lifetime reproductive success (LRS) of female Eastern Kingbirds (Tyrannus tyrannus) in central New York. I investigated the major correlates of LRS and specifically tested the hypothesis that small body size yields reproductive benefits. Lifetime reproductive success varied widely: 15–20% of females failed to fledge young over their life, whereas 50% of young were fledged by 20% of females. Female lifespan varied between one and eight years, and females that died after one breeding season tended to be smaller-bodied than long-lived females (≥2 seasons). I therefore conducted analyses of LRS for the entire sample and for longer-lived females separately. As in other species, lifespan was the strongest predictor of LRS, followed by the proportion of eggs laid that resulted in fledged young (P). Lifetime reproductive success varied positively with clutch size and, as predicted, inversely with body size (i.e., tarsus length) of females. However, variance partitioning indicated that most variation in LRS was attributable to the effects of lifespan and P, but that a substantial negative covariance existed between lifespan and P. The latter result was consistent with experimental evidence of a cost of reproduction in Eastern Kingbirds. Analysis of the correlates of lifespan, P, and clutch size showed that over a female's lifetime, (1) the longest-lived birds fledged an intermediate proportion of the eggs that they laid, (2) the most productive birds were of intermediate wing length, and (3) females with small tarsi produced the largest clutches and lost the fewest nests to predators. Hence, although lifespan was the dominant influence on LRS, negative effects of large female size appeared to be expressed through the influence of body size on other demographic parameters that contribute to LRS.Éxito Reproductivo Completo de Vida de Hembras de Tyrannus tyrannus: Influencia de la Duración de la Vida, la Depredación de Nidos y el Tamaño Corporal


The Condor ◽  
2005 ◽  
Vol 107 (3) ◽  
pp. 710-714 ◽  
Author(s):  
Christopher J. Pendlebury ◽  
David M. Bryant

Abstract Models of climate change generally predict rising mean global temperatures combined with greater variability in some regions. While relationships between mean temperature and several reproductive parameters are well documented, the effect of day-to-day variation in ambient temperature has received little attention. In our study, temperature variation had no significant effects on clutch size in a wild population of Great Tits (Parus major). In contrast, egg mass tended to be smaller when ambient temperatures during the week prior to laying were more variable. We suggest that variable temperatures may be disadvantageous to an egg-laying bird. Thermal variability should therefore be considered as a discrete factor, distinct from mean temperature, when assessing the consequences of climate changes for breeding birds. Efectos de la Variabilidad de la Temperatura sobre la Masa del Huevo y el Tamaño de la Nidada en Parus major Resumen. Los modelos de cambio climático generalmente predicen un aumento en la temperatura media global, junto con una mayor variabilidad en algunas regiones. Mientras que la relación entre la temperatura media y varios parámetros reproductivos está bien documentada, el efecto de la variación de la temperatura ambiente de un día a otro ha recibido poca atención. La variación en la temperatura no tuvo efectos significativos en nuestro estudio del tamaño de la nidada en una población silvestre de Parus major. En contraste, la masa del huevo tendió a ser menor cuando las temperaturas ambiente durante la semana previa a la puesta fueron más variables. Sugerimos que las temperaturas variables podrían ser desventajosas para un ave que está poniendo huevos. La variación térmica debería por lo tanto ser considerada como un factor discreto, diferente de la temperatura media, cuando se evalúan las consecuencias del cambio climático para las aves reproductivas.


The Auk ◽  
1983 ◽  
Vol 100 (2) ◽  
pp. 326-334 ◽  
Author(s):  
Michael T. Murphy

Abstract Observational and experimental procedures were used to evaluate the potential importance of brood size and weather on the evolution of clutch size in the Eastern Kingbird. Modal clutch size was three eggs, yet broods of four were most productive. Nestling size varied inversely with brood size, so that "nestling quality" was lower in broods of four than in broods of three. Asymptotic weight of nestlings in broods of three was directly and significantly correlated with ambient air temperature, followed by hatch order. Because larger broods were being fed during a period of relatively cool and wet weather, the effects of brood size were probably confounded by weather-induced changes in food availability, suggesting that the ability to produce surviving young successfully from large broods is dependent upon weather conditions during the nestling period. These observations match patterns seen in other aerial foragers and indicate that unpredictable changes in temperature and precipitation dramatically affect the ability of the adults to feed young. A high variance in fledging success from the largest broods is indicated and probably selects for a reduced number of offspring in the Eastern Kingbird. Trade-offs in reproductive effort and parental survival do not appear to be required to explain patterns of clutch size in the Eastern Kingbird or, probably, other aerial foragers.


2018 ◽  
Author(s):  
Michael T. Murphy ◽  
Peter Pyle

2008 ◽  
Vol 4 (6) ◽  
pp. 606-609 ◽  
Author(s):  
Dik Heg

Suppression by dominants of female subordinate reproduction has been found in many vertebrate social groups, but has rarely been shown experimentally. Here experimental evidence is provided for reproductive suppression in the group-living Lake Tanganyika cichlid Neolamprologus pulcher . Within groups of three unrelated females, suppression was due to medium- and small-sized females laying less frequently compared with large females, and compared with medium females in control pairs. Clutch size and average egg mass of all females depended on body size, but not on rank. In a second step, a large female was removed from the group and a very small female was added to keep the group size constant. The medium females immediately seized the dominant breeding position in the group and started to reproduce as frequently as control pairs, whereas clutch size and egg mass did not change. These results show that female subordinate cichlids are reproductively capable, but apparently suppressed with respect to egg laying. Nevertheless, some reproduction is tolerated, possibly to ensure continued alloparental care by subordinate females.


2021 ◽  
Author(s):  
Tim van der Schriek ◽  
Gianna Kitsara ◽  
Konstantinos V. Varotsos ◽  
Christos Giannakopoulos

&lt;p&gt;The Aegean region (Greece) preserves a wide genetic diversity amongst the honey bees (Apis mellifera L.) of its many islands and supports an important bee keeping industry. However, sector-specific regional impact studies, based on the latest high-resolution regional climate models (RCMs), are urgently required for developing successful local adaptation strategies for beekeeping and to preserve biodiversity under future climate change scenarios.&lt;/p&gt;&lt;p&gt;We evaluated direct climate change impacts on honey bees in the Aegean region through novel threshold temperature and precipitation indices, linked to critical bee behavior and colony mortality. There are strong relationships between ambient temperature and key bee colony behavior such as, for example, nest thermo-humidity regulation, annual population variability and foraging. Additionally, dry conditions and heatwaves have been empirically linked to declines in colony food stores and increased colony mortality rates. Impact projections used simulated temperature and precipitation data from an ensemble of seven RCMs under the medium (RCP4.5) and high (RCP8.5) emission scenarios for the control- (1971-2000), near future- (2031-2060) and distant future (2071-2100) periods. Simulated data were bias-adjusted using the long-term meteorological record of Naxos Island (central Aegean).&lt;/p&gt;&lt;p&gt;Overheating in summer constitutes a major challenge to nest temperature regulation. Thermal and humidity conditions are well-regulated in bee nests given their importance for colony health. Brood must remain at 33-36 &lt;sup&gt;o&lt;/sup&gt;C and experience high relative humidity for proper development. Bees tend to start cooling nests when ambient temperatures are &gt;25 &lt;sup&gt;o&lt;/sup&gt;C. Evaporative cooling using water is of critical importance with temperatures above 35 &lt;sup&gt;o&lt;/sup&gt;C and is remarkably effective in stabilising nest temperature at 36 &lt;sup&gt;o&lt;/sup&gt;C, even as ambient temperatures are &gt;60 &lt;sup&gt;o&lt;/sup&gt;C. Thermoregulation is highly demanding, and brood is mainly reared during optimum periods with no/low need of regulation. Sustained high temperatures &gt;40-45 &lt;sup&gt;o&lt;/sup&gt;C cause significant colony losses. The highest foraging activity takes place in the temperature range from 12-25&lt;sup&gt; o&lt;/sup&gt;C, whereas there is no activity &lt;7&lt;sup&gt; o&lt;/sup&gt;C and &gt;43&lt;sup&gt; o&lt;/sup&gt;C. Winter colony mortality rates increase when the spring flowering period experiences very low rainfall and extreme temperatures.&lt;/p&gt;&lt;p&gt;Future climatic change projections show significant increases in seasonal temperatures and days without precipitation, which will negatively affect the region&amp;#8217;s bees. More frequent and severe heat-extremes will characterize seasons from spring to autumn, forcing bee colonies to cool their nests more intensively. Meanwhile, the availability of water and nectar (used for evaporative cooling) will decrease during extreme warm-dry events. The increase in heat extremes will likely lead to increased colony losses. Temperatures within the range for optimal foraging activity are less likely to occur during the flowering period. Finally, years with spring seasons characterized by very low rainfall and extreme temperatures will become more frequent in the future which may result in increased winter mortality rates.&lt;/p&gt;


1970 ◽  
Vol 48 (2) ◽  
pp. 235-240 ◽  
Author(s):  
Kees Vermeer

Canada goose clutches situated on islands in Dowling Lake and Lake Newell, Alberta, were checked from laying to hatching. Egg-laying intervals averaged 1.87 days and incubation periods 26.8 days. The distribution of nests showed a significant deviation from randomness in the direction of uniform spacing. Causes of extensive hatching failure at Dowling Lake were predation and desertion. Predation by coyotes was facilitated by low water levels. A preference for nesting on islands appears to be a mechanism to counteract mammalian predation.


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