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Why do female ball pythons (Python regius) coil so tightly around their eggs?
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Question: What benefits does brooding confer to offspring viability that outweigh its costs to the nest-attending female? Organisms: Thirty captive Python regius females and their clutches. Site: Vicinity of Lomé, Togo. Background: It has previously been shown that brooding enhances ball python hatching success by reducing desiccation of eggs. Methods: We captured wild, gravid females just before the time of egg-laying. Then we varied maternal attendance, allowing it to last 0, 15 or 60 days. Conclusions: Brooding weakly influenced incubation temperature but markedly decreased egg mass loss owing to water loss and associated yolk coagulation. Brooded eggs produced larger, more active, faster swimming and more rapidly developing neonates than did non-brooded eggs.
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... For example, mass loss during the egg-caring period is observable for post-ovipositional female Eutropis (formerly Mabuya) longicaudata, but it can be balanced after a subsequent foraging period (Huang 2007). The energy cost caused by egg-caring could be trivial even during the actual egg-caring period in some snake species, such as Python regius (less than 6% mass loss in egg-caring females, Aubret et al. 2005b). Certainly, other aspects of maternal costs (e.g., increased parasite load, and reduced future survival and reproductive output) may be entailed by egg-caring behavior (Huang 2007;Stahlschmidt et al. 2012). ...
... However, only a very limited number of studies focused on reptilian species show some inconsistencies. For example, eggs cared for by post-ovipositional females produce larger and betterperforming (faster swimming and developing) hatchlings in the ball python, Py. regius (Aubret et al. 2005b), but produce smaller and poorer-performing hatchlings in the children's python, A. childreni (Stahlschmidt & DeNardo 2009b). Smaller and poor performing hatchlings were produced because coiling tightly around the eggs by females created a hypoxic incubation environment for developing embryos (Stahlschmidt & DeNardo 2008, 2009a. ...
Maternal egg-caring behavior can often be observed in oviparous scincid lizards. The expression of such behavior is predictably affected by the trade-off between its resultant costs and benefits for mothers and/or offspring, which has been investigated in only a few scincid species. Here, post-ovipositional Plestiodon chinensis females were treated to care for their egg clutches without interference, under simulated predation pressure, or to be care-deprived. Potential maternal costs and offspring benefits associated with egg-caring behavior were then evaluated by measuring changes in maternal body condition, egg mortality, and hatchling performance. Egg-caring behavior caused post-ovipositional females to participate less in outside-nest activity, eat less food, and show relatively poorer body conditions at egg hatching. By contrast, compared with care-deprived females, egg-caring females gained mass slightly faster, and achieved a similar body condition within a few months of hatching. Eggs that were cared for by their mothers were more likely to hatch and produced larger, faster-running and better-growing hatchlings with higher survival than uncared-for eggs. Simulated exposure to a potential predator had no distinct impact on maternal egg-caring behavior expression and offspring performance. These results indicated that marked benefits of offspring viability but minor maternal energy costs might play a decisive role in the occurrence of maternal egg-caring behavior in P. chinensis.
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... High temperatures during embryonic development may have a direct influence on scutellation, as reported by Lourdais et al. (2004) in Vipera aspis, or morphology, as reported by Aubret et al. (2005) in Python regius. Similarly, Aubret (2012) points out that variables such as the availability of prey directly influence body size in snakes. ...
We assessed whether morphological variability in populations of Pituophis deppei is related to the ecogeographic conditions of the biogeographic provinces they inhabit. This study includes four biogeographic provinces where the Mexican Pine Snake is reported: the Mexican Plateau, the Trans-Mexican Volcanic Belt, the Sierra Madre Occidental, and the Sierra Madre Oriental, Mexico. Specimens from the four biogeographic provinces were selected to analyze ecogeographic and morphological variation in the Mexican Pine Snake. A total of 789 occurrence records and 20 climatic and environmental variables were used to evaluate the overlap, conservatism, and divergence of ecological niches among the four provinces using an ecological niche model (ENM) for each one. Morphological variability was analyzed using geometric morphometrics with linear and discrete data from 262 specimens. The ENM results indicate that the distribution area of P. deppei is subdivided into four well-defined regions of habitat suitability associated with the Mexican Plateau, the Trans-Mexican Volcanic Belt, the Sierra Madre Oriental, and the Sierra Madre Occidental, with contact zones at their borders. These results indicate low overlap among the four provinces. Niche conservatism and niche divergence were supported by three and two pairwise comparisons, respectively. At the morphological level, linear morphometrics, scutellation, and black spot pattern accounted for enough variability to discriminate the specimens found in the Trans-Mexican Volcanic Belt from those of the other three provinces. As expected, the pattern of variation in head shape consists of well-defined character states exclusive to each of the four provinces inhabited by P. deppei. All the comparisons from the multivariate analyses of variance of landmark configurations with CVA were statistically significant, and the rates of correct posterior classifications were all above 35.5%. The ecogeographic variables used show reduced explanatory and predictive power for the variation in the morphological characters analyzed. The morphological variation in P. deppei could result from factors not considered in the present study, such as differences in trophic ecology, limited gene flow, non-adaptative variation, or phylogeographic implications. In the latter case, the morphological results obtained are consistent with one southern lineage previously reported using the haplotype configuration of species of P. deppei. Finally, our geometric morphometric approach allowed us to analyze head shape variability in P. deppei. Se evalu si la variabilidad morfolgica de las poblaciones de Pituophis deppei est relacionada con las condiciones ecogeogrficas de las provincias biogeogrficas que habita. Este estudio incluye cuatro provincias biogeogrficas donde se reporta a la serpiente de pino mexicana: El Altiplano Mexicano, la Faja Volcnica Trans-Mexicana, la Sierra Madre Occidental y la Sierra Madre Oriental, Mxico. Se seleccionaron especmenes de las cuatro provincias biogeogrficas para el anlisis de la variacin ecogeogrfica y morfolgica de la culebra de pino mexicana. Se utiliz un total de 789 registros de ocurrencia y 20 variables climticas y ambientales para evaluar el traslape, conservadurismo y divergencia de nichos ecolgicos entre las cuatro provincias, utilizando un modelo de nicho ecolgico (ENM) para cada una de ellas. La variabilidad morfolgica se analiz mediante morfometra geomtrica, lineal, escutelacin y patrn de manchas negras de 262 ejemplares. Los resultados de la ENM indican que el rea de distribucin de P. deppei se subdivide en cuatro regiones bien definidas de idoneidad de hbitat asociadas al Altiplano Mexicano, la Faja Volcnica Trans-Mexicana, la Sierra Madre Oriental y la Sierra Madre Occidental, con zonas de contacto en sus lmites. Estos resultados suponen un bajo solapamiento entre las cuatro provincias analizadas. El conservadurismo de nicho y la divergencia de nicho fueron apoyados por tres y dos comparaciones por pares, respectivamente. A nivel morfolgico, la morfometra lineal, la escutelacin y el patrn de manchas negras fueron los responsables de la variabilidad para discriminar los especmenes encontrados en la Faja Volcnica Trans-Mexicana respecto a las otras tres provincias. Como se esperaba, el patrn de variacin en la forma de la cabeza consiste en estados de carcter bien definidos y exclusivos de cada una de las cuatro provincias donde habita P. deppei. Todas las comparaciones en los anlisis multivariados de varianza de las configuraciones de los puntos de referencia con el CVA fueron estadsticamente significativas, y las tasas correctas de clasificacin posterior fueron todas superiores al 35,5%. Finalmente, las variables ecogeogrficas utilizadas muestran un reducido poder explicativo y predictivo de la variacin de los caracteres morfolgicos analizados. La variacin morfolgica en P. deppei podra ser el resultado de factores no considerados en el presente estudio, como diferencias en la ecologa trfica, flujo gentico limitado, variacin no adaptativa o implicaciones filogeogrficas. En este ltimo caso, los resultados morfolgicos obtenidos coinciden con un linaje meridional previamente reportado utilizando la configuracin de haplotipos de las especies de P. deppei. Por ltimo, nuestro enfoque morfomtrico geomtrico nos permiti analizar la variabilidad de la forma de la cabeza en P. deppei.
... Guided by environmental and social clues (e.g. empty shells of previous hatchlings, Brown & Shine, 2005a;Meek, 2017) and using their spatial memory, gravid females search underground tunnels or cavities for localities with stable ambient temperatures of around 30 -35 °C and high moisture levels, which produce optimal conditions for embryo development (Shine et al., 1997;Aubret et al., 2005;Brown & Shine, 2005b;Löwenborg et al., 2010Löwenborg et al., , 2011Ramesh & Bhupathy, 2010;Stahlschmidt et al., 2011;Meek, 2017). Such conditions can be represented by large partly rotting logs, hollow trees, thick leaf litters, underground insect nests or the burrows of various animals (Carman- Blazquez & Villafuerte, 1990;Madsen & Shine, 1999;Pearson et al., 2003;Velásquez-Múnera et al., 2008;Ramesh & Bhupathy, 2010;Nagy et al., 2017;Meek, 2017;Alexander, 2018). ...
Published by the British Herpetological Society.
Oviparous snakes deposit their egg clutches in sites sheltered from predation and from strong thermal and hydric fluctuations. Appropriate laying sites with optimum thermal and hydric conditions are generally scarce and are not necessarily localised in the home range. Thus, many gravid females undertake extensive trips for oviposition, and many may converge at the best egg laying sites. Dispersal mortality of neonates post-hatchling is also a critical factor. Assessing the parameters involved in this intergenerational trade-off is difficult however, and no study has succeeded in embracing all of them. Here we report data indicating that gravid females of the highly mobile European whip snake, Hierophis viridiflavus exhibit nest site fidelity whereby they repeatedly deposit their eggs in cavities under sealed roads over many decades. These anthropogenic structures provide benefits of relative safety and suitable incubation conditions (due to the protective asphalted layer?), but they expose both females and neonates to high risk of road mortality. Artificial laying sites constructed at appropriate distances from busy roads, along with artificial continuous well protected pathways (e.g. dense hedges) that connect risky laying sites to safer areas, should be constructed.
... For example, it has been demonstrated that crocodilian embryos produce vocalisations and also respond to those of their nest-mates (Vergne & Mathevon, 2008 predation risk, such as demonstrated in yellow-legged gull Larus michahellis embryos (Noguera & Velando, 2019), or optimal hatching conditions, as is the case in pig-nosed turtles Carettochelys insculpta (Doody et al., 2012). In taxa where parents brood or incubate the eggs [chiefly birds, but also pythons (Aubret et al., 2005), monotreme mammals (Beard & Grigg, 2000), and several amphibian species (Stebbins & Cohen, 1995)], embryos may also gain considerable information from parental behaviours. For example, parental vocalisations produced while on the nest have been suggested to influence nestling phenotype in zebra finches Taeniopygia guttata (Mariette & Buchanan, 2016), although whether or not such vocalisations are indeed adaptive is still debated (McDiarmid, Naguib & Griffith, 2018Mariette & Buchanan, 2019). ...
Maternal effects, or the influence of maternal environment and phenotype on offspring phenotype, may allow mothers to fine‐tune their offspring's developmental trajectory and resulting phenotype sometimes long after the offspring has reached independence. However, maternal effects on offspring phenotype do not evolve in isolation, but rather within the context of a family unit, where the separate and often conflicting evolutionary interests of mothers, fathers and offspring are all at play. While intrafamilial conflicts are routinely invoked to explain other components of reproductive strategy, remarkably little is known about how intrafamilial conflicts influence maternal effects. We argue that much of the considerable variation in the relationship between maternally derived hormones, nutrients and other compounds and the resulting offspring phenotype might be explained by the presence of conflicting selection pressures on different family members. In this review, we examine the existing literature on maternal hormone allocation as a case study for maternal effects more broadly, and explore new hypotheses that arise when we consider current findings within a framework that explicitly incorporates the different evolutionary interests of the mother, her offspring and other family members. Specifically, we hypothesise that the relationship between maternal hormone allocation and offspring phenotype depends on a mother's ability to manipulate the signals she sends to offspring, the ability of family members to be plastic in their response to those signals and the capacity for the phenotypes and strategies of various family members to interact and influence one another on both behavioural and evolutionary timescales. We also provide suggestions for experimental, comparative and theoretical work that may be instrumental in testing these hypotheses. In particular, we highlight that manipulating the level of information available to different family members may reveal important insights into when and to what extent maternal hormones influence offspring development. We conclude that the evolution of maternal hormone allocation is likely to be shaped by the conflicting fitness optima of mothers, fathers and offspring, and that the outcome of this conflict depends on the relative balance of power between family members. Extending our hypotheses to incorporate interactions between family members, as well as more complex social groups and a wider range of taxa, may provide exciting new developments in the fields of endocrinology and maternal effects.
... Parental and maternal care of eggs is observed in a wide range of taxa (Royle et al., 2012) and improves the survival of offspring by protection against predators (Evans, 1998;Croshaw & Scott, 2005;Requena et al., 2009), by grooming and incubation (Aubret et al., 2005;Mungu ıa-Steyer et al., 2008;Boos et al., 2014). However, prey individuals that take care of their eggs may themselves be more susceptible to attack by predators than those that do not exhibit such behavior (Reguera & Gomendio, 1999;Li & Jackson, 2003;Suzuki & Futami, 2018). ...
Predators frequently compete with other species for prey but can also interact by preying on each other’s vulnerable stages. Because eggs and juveniles are more vulnerable to this intraguild predation than adults, their survival will depend on maternal strategies to reduce predation risk. Recently, we reported that adult female predatory mites Gynaeseius liturivorus Ehara (Acari: Phytoseiidae) reduce intraguild predation on their eggs by remaining at oviposition sites, thus deterring the egg predators. In addition, they avoid oviposition close to eggs laid by conspecific females. We therefore expected that adult female G. liturivorus protect their own eggs better against these egg predators than eggs of other females. This was tested using juveniles of the predatory mite Neoseiulus californicus McGregor (Acari: Phytoseiidae) as egg predators and the western flower thrips, Frankliniella occidentalis Pergande (Thysanoptera: Thripidae), as the shared prey. When G. liturivorus eggs were kept with their mothers, the presence of juvenile egg predators did not affect the survival of eggs. However, when G. liturivorus eggs were kept with females that were not their mothers, the mortality of eggs in the presence of juvenile egg predators increased. When adult female G. liturivorus were guarding their eggs, they killed a similar number of juvenile egg predators as females that were not kept with their eggs. Hence, adult female G. liturivorus protect their eggs by remaining close to their eggs. Predators frequently compete with other species for prey but can also interact by preying on each other’s vulnerable stages. Previously, we showed that adult female predatory mites remain at oviposition sites, thus deterring juveniles of another predatory mite species, resulting in reduced intraguild predation on their eggs. We now show that this guarding behavior is more effective when adult females guard their own eggs than when guarding eggs of other females.
... Further, while eggs incubated at LE tended to gain mass during incubation, eggs incubated at EHE maintained their mass over the same period (Fig. 2a), suggesting a low efficiency of water or carbon dioxide diffusion (Cunningham & Hurwitz 1936). Excessive water loss in snake eggs may gradually increase yolk viscosity and impede absorption by the developing embryo (Cunningham & Hurwitz 1936;Aubret et al. 2005b). Eggs exposed to EHE, by losing excessive water, may have exposed the embryo to a similar constraint, leading to lesser yolk intake (and higher amounts of residual yolk post-hatching) and consequently smaller body size at hatching (Table 2). ...
Climate change is generating range shifts in many organisms, notably along the elevational gradient in mountainous environments. However, moving up in elevation exposes organisms to lower oxygen availability, which may reduce the successful reproduction and development of oviparous organisms. To test this possibility in an upward‐colonizing species, we artificially incubated developing embryos of the viperine snake (Natrix maura , Linnaeus 1758), using a split‐clutch design, in conditions of extreme high elevation (hypoxia at 2877 m above sea level; 72% sea‐level equivalent O2 availability) or low elevation (control group; i.e. normoxia at 436 m above sea level). Hatching success did not differ between the two treatments. Embryos developing at extreme high elevation had higher heart rates and hatched earlier, resulting in hatchlings that were smaller in body size and slower swimmers compared to their siblings incubated at lower elevation. Furthermore, post‐hatching reciprocal transplant of juveniles showed that snakes which developed at extreme high elevation, when transferred back to low elevation, did not recover full performance compared to their siblings from the low elevation incubation treatment. These results suggest that incubation at extreme high elevation, including the effects of hypoxia, will not prevent oviparous ectotherms from producing viable young, but may pose significant physiological challenges on developing offspring in ovo . These early‐life performance limitations imposed by extreme high elevation could have negative consequences on adult phenotypes, including on fitness‐related traits.
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... 70%) captured a maximum of five ball pythons per trip (n = 40), and fewer than six or seven eggs per trip (n = 35 and 40, respectively) (most likely a single clutch of eggs). Most ball python clutches comprise five to eight eggs (Aubret et al. 2003), and the eggs are strongly adherent so it is not possible to separate them without damaging the shell (Aubret et al. 2005). ...
The ball python ( Python regius ) is the single most exported live CITES-listed species from Africa, with a large proportion of snakes being sourced from Togo, West Africa, officially via a system reported nationally as “ranching”. This study represents the first in-depth review of ball python hunting being carried out by rural communities in Togo for nearly 15 years. Our approach, focused at the bottom of the trade chain, permitted extensive detailed data to be collected from hunters, and provides a unique insight into the practices, drivers and impacts associated with this type of large-scale commercial wildlife trade activity. We show that ball python hunting remains an economically valuable endeavour for these rural hunters. However, it also highlights a number of potential legal, conservation and animal welfare issues associated with the current hunting practices being carried out in Togo (and neighbouring range States) to supply the snake farms and ultimately the international exotic pet trade. Our findings suggest that the methods applied on the ground do not accurately reflect those being reported to national authorities and international regulatory mechanisms such as CITES. This irregular, if not illegal, trade may also be unsustainable, as suggested by hunters reporting that there are fewer ball pythons in the wild than there were five years previously. We recommend that additional scientific investigation (focusing on the size and status of the wild population), better management, and enforcement of regulations, are required to ensure that ball python populations are managed in a sustainable, legal and traceable way.
... Independent of the absence of kin bias, our results confirm that maternal presence is crucial to maximize hatching success in earwigs (Boos et al. 2014). Across species and taxa, the presence of mothers with eggs often mitigates the costs of external stressors acting during egg development, such as predation (Swennen et al. 1993;Machado and Oliveira 2002;Requena et al. 2009;Miller et al. 2011), pathogen infection (Grindstaff et al. 2003;Herzner and Strohm 2007;Kudo et al. 2011;Trumbo 2012;Boos et al. 2014), desiccation (Aubret et al. 2005;Poo and Bickford 2013), and other environmental changes (Green and McCormick 2004;Smiseth et al. 2012). Given the standard laboratory conditions used in the present study, our findings suggest that maternal presence buffers the otherwise lethal effects of small variation in the nesting environment, for example, humidity and/or the development of nonpathogenic microbes such as mold (see also Boos et al. 2014). ...
The rejection of foreign individuals is considered a central parameter in the evolution of social life. Within family units, parents are typically thought to reject foreign offspring to ensure that their investment into care is directed towards their own descendants. Whereas selection for such kin bias is expected to be high when parental care is extended and involves numerous and energetically costly behaviors, it can be reduced when the acceptance of foreigners provide subsequent benefits to offspring and when alternative parental strategies limit the risk of clutch parasitism. In this study, we investigated the outcome of these conflicting selection pressures in the European earwig. Our results overall demonstrate that mothers do not eliminate foreign eggs, provide the same level of care to both foreign and own eggs (egg grooming, egg defense, and maternal return) and pay the same costs of care in terms of weight loss and immunity when tending each type of eggs. We also show that foreign and own eggs exhibit similar development time, hatching success and lead to comparable juvenile quality. Interestingly, our results reveal that tending eggs (of any origin) reduces mothers' weight loss during this long period, possibly due to egg cannibalism. Hence, these findings emphasize the difficulty to predict the occurrence of kin bias, and stress the need to broaden our knowledge on the net benefits of egg rejection for parents to better understand the general importance of kin bias in the evolution of pre-hatching parental care.
... Producing clusters of eggs is an effective way of facilitating the care of offspring 1 3 (Kudô et al. 1989;Buzatto et al. 2007;Poo and Bickford 2013;Giffney and Kemp 2016). Specific behaviors to take care of eggs, such as grooming, was not observed in G. liturivorus although it has been reported for other animals (Aubret et al. 2005;Munguía-Steyer et al. 2008;Boos et al. 2014). Thus, the aim of producing clusters of eggs by G. liturivorus mothers would not be for taking care of own eggs. ...
Animals often select oviposition sites to minimize the predation risk for eggs and juveniles, which are more vulnerable to predation than adults. When females produce eggs in clusters, the eggs and juveniles are likely to suffer from cannibalism. Although cannibalism among siblings is known to be lower than among non-siblings, there have been few investigations into the possibility that females select oviposition sites that reduce the risk of cannibalism for the offspring. To test this possibility, we examined oviposition preference by adult females of the predatory mite Gynaeseius liturivorus in response to the presence of her own eggs and to eggs of other females, offering plastic discs as oviposition substrates. Although females did not clearly show a preference for plastic discs on which they had oviposited, they avoided plastic discs on which other females had oviposited. When eggs of other females were artificially placed on clean plastic discs, adult female mites avoided these discs, suggesting that the eggs were used as cues for oviposition preference. Cannibalism among juvenile siblings was lower than among non-siblings. These observations show that adult females and juveniles of G. liturivorus discriminate kin relationships among conspecific individuals. Therefore, oviposition preference by adult female G. liturivorus may lead to the reduced risk of cannibalism among offspring.
... From the perspective of the offspring, egg mass in squamates is typically positively correlated with offspring size [53,54]. Additionally, the egg mass difference we report probably reflects reduced water allocation, and lower egg watercontent reduces embryonic yolk absorption, resulting in smaller size and reduced offspring performance [55,56]. ...
The use of fat to support the energy needs of reproduction (i.e. capital breeding) has been studied in a diversity of taxa. However, despite reproductive output (i.e. young or eggs) being approximately 70% water, little is known about the availability of internal resources to accommodate the hydric demands of reproduction. Recent research suggests that dehydration increases the catabolism of muscle as a means of maintaining water balance. Accordingly, we investigated the interactive effects of reproductive investment and water deprivation on catabolism and reproductive output in female Children's pythons (Antaresia childreni). Both reproductive and non-reproductive females were either provided water ad libitum or were water-deprived for three weeks at the time when reproductive females were gravid. We found that water-deprived reproductive females had, in general, greater body mass loss, epaxial muscle loss, plasma osmolality and plasma uric acid concentrations relative to the other groups. Furthermore , water-deprived females had similar clutch sizes compared with females with access to water, but produced lighter eggs and lower total clutch masses. Our results provide the first evidence that selective protein catabolism can be used to support water demands during reproduction, and, as a result, these findings extend the capital breeding concept to non-energetic resources.
Embryos incubated at 32 and 35°C hatch c10 days before those of 28°C and over 5 wk before those of 24°C. Hatching success was high at 24°C and 28°C but much lower at higher temperatures (32 and 35°C). Neonates incubated at low temperatures had larger snout-vent lengths and body masses, grew faster, and had higher sprint speeds than hatchlings incubated at higher temperatures. Hence, incubation temperatures that accelerate embryo development (32-35°C) did not maximize embryo survival and hatchling characteristics. An incubation temperature of 28°C provided the best balance between developmental rate, hatching success, and posthatch performances. -from Authors
This paper reports data on the mobilization of some yolk and eggshell nutrients and their incorporation into hatchlings and post-hatching yolk in an oviparous colubrid snake, Elaphe carinata. The incubation time at 30±0.3°C averaged 50.5 days. During incubation, pliable-shelled E. carinata eggs increased in wet mass. Dried shells from freshly laid eggs averaged 8.1% of the entire egg dry mass. Freshly laid eggs had significantly heavier shells than did hatched eggs with the same wet mass at oviposition. Dry mass conversion from egg contents of the freshly laid egg to hatchling averaged 81.1%. During incubation, approximately 63.7% of non-polar lipids and 72.1% of energy in egg contents of the freshly laid egg were transferred to the hatchling, with 36.3% of non-polar lipids and 27.9% of energy used for embryogenesis. Shells from freshly laid eggs had a higher level of calcium but a lower level of magnesium than did shells from hatched eggs. Fully developed embryos could obtain all magnesium from yolk but withdrew approximately 30.5% of their total calcium requirements from sources other than yolk. A few days after hatching, a decrease in post-hatching yolk dry mass was accompanied by an increase in carcass dry mass. This confirms that post-hatching yolk could be used to support early growth of hatchlings.