Egg Data Slips: Are They Useful for Information on Egg-Laying Dates and Clutch Size?

The Condor ◽  
1987 ◽  
Vol 89 (2) ◽  
pp. 369 ◽  
Author(s):  
Douglas B. McNair
Keyword(s):  

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.



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.







2012 ◽  
Vol 58 (6) ◽  
pp. 820-827 ◽  
Author(s):  
Long-Hui Lin ◽  
Fei Mao ◽  
Ce Chen ◽  
Xiang Ji

Abstract We collected gravid gray rat snakes Ptyas korros from three geographically distinct populations in China, Chenzhou (CZ), Jiangshan (JS) and Dinghai (DH), to study geographical variation in female reproductive traits. Egg-laying dates differed among the three populations such that at the most northern latitude egg-laying was latest, and earliest at the most southern lati-tutde. Clutch size, clutch mass, egg mass, egg shape, within clutch variability in egg sizes and relative clutch mass differed among the three populations, whereas post-oviposition body mass did not. Except for egg-laying date, none of the traits examined varied in a geographically continuous trend. CZ and DH females, although separated by a distance of approximately 1100 km as the crow flies, were similar in nearly all traits examined. JS females were distinguished from CZ and DH females by their higher fecundity (clutch size), greater reproductive output (clutch mass) and more rounded eggs. Our data do not validate the prediction that larger offspring should be produced in colder localities. The absence of an egg size-number trade-off in each of the three populations presumably suggests that P. korros is among species where eggs are well optimized for size within a population.



2009 ◽  
Vol 151 (1) ◽  
pp. 11-17 ◽  
Author(s):  
Joël M. Durant ◽  
Jean-Paul Gendner ◽  
Yves Handrich


2019 ◽  
Author(s):  
Jorge García-Campa ◽  
Wendt Müller ◽  
Sonia González-Braojos ◽  
Emilio García-Juárez ◽  
Judith Morales

During egg laying, female birds face a trade-off between self-maintenance and investment into current reproduction. Providing eggs with resources is energetically demanding, since in most species females lay one egg per day. However, the costs of egg laying not only relate to energetic requirements, but also depend on the availability of specific resources that are vital for egg production and embryonic development. One of these compounds are carotenoids, pigments with antioxidant properties and immuno-stimulatory functions, which are crucial during embryonic development. In this study, we explore how carotenoid availability alleviates this trade-off and facilitates egg laying in the blue tit. Blue tit females lay one egg per day and have the largest clutch size of all European passerines. We performed a lutein supplementation experiment, and measured potential consequences for egg laying capacity and egg quality. We found that lutein-supplemented females had less laying interruptions and thus completed their clutch faster than control females. No effects of treatment were found on the onset of egg laying or clutch size. Experimentally enhanced carotenoid availability did not elevate yolk carotenoid levels or egg mass, but negatively affected eggshell thickness. Our results provide hence evidence on the limiting role of carotenoids during egg laying, However, the benefits of laying faster following lutein supplementation were counterbalanced by a lower accumulation of calcium in the eggshell. Thus, even though single components may constrain egg laying, it is the combined availability of a range of different resources which ultimately determines egg quality and thus embryonic development.



2015 ◽  
Vol 42 (2) ◽  
pp. 169-181
Author(s):  
Md Lokman Hossain ◽  
Shorab Uddin Sarker ◽  
Noor Jahan Sarker

This study was conducted to determine the breeding season, gonad development, egg laying period, clutch size and other biological aspects of Bengal Eyed Turtle, Morenia petersi of Bangladesh. The egg-laying period was found between November and February. The nesting sites were elevated fallow lands in secluded areas. The female turtle laid all the mature eggs at a time for each clutch at night. A gravid female turtle laid two clutches of eggs in each breeding season and the mean clutch size was 9.7 ± 1.5 eggs and mean weight of each egg was 8.9 ± 1.3 g. The eggs are elongated in shape and whitish in colour. The mean incubation period was 119 ± 30 days. The incubation period of first clutch was the longer than the second clutch. The hatchlings emerged out between April and May. Hatchery success was found 56.8%. The percentage of weight gain and specific growth rate (SGR) by weight of hatchlings in the first year was greater than second and third year. Present investigation was made to explore the possibility to raise turtle farming in captive condition.Bangladesh J. Zool. 42(2): 169-181, 2014



The Auk ◽  
2003 ◽  
Vol 120 (2) ◽  
pp. 481-489
Author(s):  
Tony D. Williams ◽  
Melinda Miller

Abstract We investigated individual and resource-dependent variation in ability of female Zebra Finches (Taeniopygia guttata) to lay supranormal clutches in response to egg removal, and effect of continuous laying on (1) egg composition and (2) plasma yolk precursor levels. Egg removal significantly increased the number of eggs that individual females laid, but that response was diet-dependent: on a high-quality (egg-supplemented) diet, females laid 12.4 ± 1.0 more eggs compared with their pretreatment clutch size; whereas on the low-quality (seed-only) diet, females laid only 4.9 ± 1.2 more eggs. Removal clutch size (i.e. total number of eggs laid in response to egg removal) was positively correlated with pretreatment mean egg mass and clutch size on the low-quality diet, but not on the high-quality diet. That suggests that there is interindividual variation in egg-laying ability (“large-egg” females had a greater capacity to respond to egg removal than “small-egg” females), but that higher resource levels can overcome individual differences. Egg mass did not vary with laying sequence in supra-normal clutches (up to 22 eggs); however, there was a significant decrease (6%) in yolk protein content of additional eggs that was apparent by the tenth egg laid (i.e. only 4–5 more than the normal clutch size). Plasma levels of the two yolk precursors, vitellogenin and very-low-density lipoprotein (VLDL), were independent of diet and did not differ in individual birds at the 1 egg stage versus the 14 egg stage. However, there was a systematic change in relationship between yolk lipid content and plasma VLDL levels, from nonsignificant for third-laid eggs to significant and positive for sixteenth-laid eggs. We propose a possible mechanism linking female condition and egg-laying ability: good quality females, capable of laying extended clutches, are able to maintain production of generic VLDL for their own metabolic needs, as well as producing yolk-targeted VLDL, whereas poor quality females are not.



The Auk ◽  
2001 ◽  
Vol 118 (3) ◽  
pp. 624-635 ◽  
Author(s):  
Ulf Wiktander ◽  
Ola Olsson ◽  
Sven G. Nilsson

Abstract We examined the influence of female age, male age, and pair-bond duration on start of egg-laying, clutch size, and number of young fledged in the Lesser Spotted Woodpecker (Dendrocopos minor). We also attempted to disentangle the relative influence of individual age and pair-bond duration on reproduction, because the effect of those factors may be confounded. Breeding performance improved with age in that old females started egg-laying earlier and old males raised more young than yearlings, and old pairs both started egg-laying earlier and raised more young than new pairs. Clutch size was not affected by age, but showed a strong negative relation with laying date. Late-laying yearling females experienced a lower survival, and the survival of yearling males showed a positive relation with fledgling production. That differential survival was a likely mechanism explaining the differences in reproductive performance between yearling and old birds. Several analyses suggested that pair-bond duration had independent positive effects on reproduction. Benefit of long-term pair-bonds appeared to depend upon repeated breeding with a particular partner. The mechanisms behind the benefit of remating with a particular partner remain unclear, however. We postulate that much of the patterns of age effects on reproduction in the Lesser Spotted Woodpecker may be caused by constraints posed by the territorial system and effects of territory quality, although effects of individual quality can not be excluded.



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