Breeding biology of the White-rumped Swallow Tachycineta leucorrhoa in Buenos Aires Province, Argentina

We conducted a study of the breeding biology of the White-rumped Swallow Tachycineta leucorrhoa nesting in nestboxes in a flat, farming landscape in Buenos Aires Province, Argentina. White-rumped Swallow nesting attempts were detected from the end of September to mid December, with most clutches laid during October. Birds laid clutches of 4–6 eggs with a mode of five eggs; most broods hatched synchronously (58%), but hatching spread could last up to 4 days. Nestling growth curves adjust well to logistic functions, and at day 15 nestlings attain the asymptotic weight of 21.6 g. Clutch size in White-rumped Swallows declined significantly as the season progressed. In addition, late-season eggs were smaller and late-season nestlings had a shorter nestling period and lower weight at day 15, probably leaving the nest lighter than early-season nestlings. These data suggest that the Swallows would benefit greatly from laying early in the season, which would provide nestlings with better survival prospects. However, both major sources of nest mortality, interspecific competition for nest-sites and nestling mortality during bad weather, decreased through the season. White-rumped Swallows follow the pattern found for other southern species, as it has smaller clutch size, lower growth rate and remains longer at the nest than its Northern Hemisphere congener the Tree Swallow Tachycineta bicolor .     

Breeding biology of the Barn Owl Tyto alba in central Mali

Data were obtained on 178 clutches of African Barn Owls in central Mali from four breeding seasons during 1979–1983. Significantly more clutches were laid in 1979–1980 and significantly fewer in 1980– 1981 than the average for the 4 years and there were significantly more clutches laid in the middle period of the annual breeding season. The egg volume was significantly smaller at the beginning of the breeding season and significantly larger in the middle than the overall mean with eggs of second clutches being larger than those of first clutches. The clutch size was 605 eggs of which 479 hatched. The number of young fledged per successful nest was 319 and was 1 83 for all nesting attempts. The month was the only variable shown to affect significantly the clutch size, eggs hatched and fledging rate, the highest success rates being associated with the middle of the breeding period. The average interval between the hatching of eggs was 2–31 days. Survival rates (47'1%) to fledging were significantly affected by year (1981–1982 being the least) and month (mid-season birds the best). The order of hatching significantly affected age at death or disappearance, the first-hatched birds surviving the longest. The year significantly affected age at fledging, the young from the year in which most clutches were laid leaving the nest at the youngest age and those associated with the year having the least number of clutches remaining in the nest the longest. The month of hatching also affected fledging age, birds at the extremes of the breeding season fledging at older ages. The discussion compares these data with those from elsewhere.     

Intraseasonal effects of clutch manipulation on parental provisioning and residual reproductive value of eastern phoebes (Sayornis phoebe)

Summary First clutches of double-brooded eastern phoebes Sayornis phoebe were manipulated (up two eggs, down 2 eggs or no change) to test for intraseasonal reproductive tradeoffs and to test whether size of first brood influenced food delivery rates to nestlings and nestling quality in second broods.Considering all nests from both broods, rate of feeding nestlings increased linearly with brood size but nestling mass per nest decreased with increasing brood size. High nestling weights in small broods may have resulted from parents delivering better quality food, but we did not test this.Among treatment groups in first broods, nestlings from decreased broods weighed more than those in control or increased broods. Treatment did not influence the likelihood that second nests would be attempted after successful first nests nor did it alter the interval between nests. Nestlings of parents that renested weighed more than those of parents that did not, regardless of treatment, suggesting that post-fledging care may preclude renesting. Mass of individual females did not change between broods, regardless of brood size. Clutch sizes of second attempts were not affected by manipulations of first broods but increasing first broods reduced the number of nestlings parents were able to raise to day 11 in their second broods. However, manipulation of first broods did not affect mean nestling mass per nest of nestlings that survived to day 11.In phoebes, parents of small first broods are able to raise nestlings in better condition. We predict that in harsh years, parents of small first broods would be more likely to renest. Parents of enlarged first broods sacrificed quality of offspring in second broods, which seems a reasonable strategy if nestlings from second broods have lower reproductive value.     

Incubation capacity contributes to constraints on maximal clutch size in Brent Geese Branta bernicla nigricans

Lack ( 1967 ) proposed that clutch size in species with precocial young was determined by nutrients available to females at the time of egg formation; since then others have suggested that regulation of clutch size in these species may be more complex. We tested whether incubation limitation contributes to ultimate constraints on maximal clutch size in Black Brent Geese (Black Brant) Branta bernicla nigricans. Specifically, we investigated the relationship between clutch size and duration of the nesting period (i.e. days between nest initiation and the first pipped egg) and the number of goslings leaving the nest. We used experimental clutch manipulations to assess these questions because they allowed us to create clutches that were larger than the typical maximum of five eggs in this species. We found that the per‐capita probability of egg success (i.e. the probability an egg hatched and the gosling left the nest) declined from 0.81 for two‐egg clutches to 0.50 for seven‐egg clutches. As a result of declining egg success, clutches containing more than five eggs produced, at best, only marginally more offspring. Manipulating clutch size at the beginning of incubation had no effect on the duration of the nesting period, but the nesting period increased with the number of eggs a female laid naturally prior to manipulation, from 25.4 days (95% CI 25.1–25.7) for three‐egg clutches to 27.7 days (95% CI 27.3–28.1) for six‐egg clutches. This delay in hatching may result in reduced gosling growth rates due to declining forage quality during the brood rearing period. Our results suggest that the strong right truncation of Brent clutches, which results in few clutches greater than five, is partially explained by the declining incubation capacity of females as clutch size increases and a delay in hatching with each additional egg laid. As a result, females laying clutches with more than five eggs would typically gain little fitness benefit above that associated with a five‐egg clutch.     

THE BIRDS OF LANGEBAAN LAGOON

Data are presented on breeding success of Red Bishops (Euplectes orix) collected over four breeding seasons at a colony in the Addo Elephant National Park, Eastern Cape, South Africa. Overall hatching and fledging success were 53.8% and 26.0% of all eggs laid, respectively, and the overall mean number of fledglings per breeding attempt was 0.77. Hatching and fledging success varied significantly among seasons, with both clutch and brood losses due to predation being the main reason for the observed differences. Hatching success also differed significantly among clutch sizes, being highest for four-egg clutches (63.2%), intermediate for three-egg clutches (55.5%) and lowest for two-egg clutches and five-egg clutches (33.2% and 34.3%, respectively). However, fledging success was not significantly different among clutch sizes. The mean number of fledglings per breeding attempt was 0.44 for two-egg clutches, 0.80 for three-egg clutches, 1.10 for four-egg clutches, and 0.57 for five-egg clutches. The height of accepted nests (i.e.nests in which at least one egg was laid) was significantly lower than the height of nests not accepted. In addition, accepted nests in which eggs hatched and young fledged were significantly lower than accepted nests in which no eggs hatched and no young fledged. These overall effects of nest height on nest acceptance and hatching and fledging success were, however, due only to nests built above water, since no such effects were found when nests built above ground (i.e.on dry land) were analysed separately. I detected no effect of nest coverage on the probability of a nest being accepted, nor was there any effect of nest coverage on hatching or fledging success. Nests above water were significantly more likely to be accepted than nests above ground; however, hatching and fledging success of nests that were accepted did not differ significantly between nests built above water and those built above ground.     

Patterns of variation in size of Boat-tailed Grackle Quiscalus major eggs

Boat-tailed Grackle Quiscalus major eggs averaged 8^.09 g wet weight. Mean egg weight represented 8 05 % of female body weight. Based on egg weight, Grackle eggs have a shorter incubation period than the general passerine pattern.
Egg weight varied significantly with sequence of laying and between clutches in both two-egg and three-egg clutches. Last laid eggs weighed less than first laid eggs. The mean weight of the first two eggs laid in three-egg clutches did not differ from the mean egg weight of two-egg clutches. The average clutch of two and three eggs weighed 16.33 g and 24.16 g, respectively.
Mean egg weight varied between study colonies and with season. Grackles at East Lake laid eggs that weighed less than grackles at either Alligator Lake or North Lake. Eggs laid during March averaged less than eggs laid later in the season. The locality variation reflects the different timing of nesting between sites rather than food abundance. As nutrient provisioning increases with an increase in egg weight, the seasonal change in egg weight probably reflects improved feeding conditions for the female. This suggests that selection favours beginning laying before reserves of the female are sufficient to lay the largest egg possible.
The size of the young at hatching was correlated with egg size. Newly hate had young averaged 79.6% of fresh egg weight. Egg weight did not determine the probability of hatching or starvation of the young. Females do not appear to adjust egg size facultatively depending on the sex of the young. Eggs producing males and females did not vary significantly in weight, whether comparisons were made within or between clutches.     

Breeding success and the question of clutch size of Northwestern Crows Corvus caurinus

The breeding biology of two island populations of the Northwestern Crow was studied in British Columbia over a period of five years. Both populations laid an average of four eggs per clutch, of which approximately 75% hatched. More young survived to fledge on Mandate than on Mitlenatch Island. The young from nests close (< 100 m) to the beach on Mitlenatch had a higher survival rate than those from further inland. The number of eggs lost or failing to hatch was lowest in clutches of four eggs. There was a non-significant trend for chick survival to be inversely related to clutch size. The net result was that clutches of five eggs produced no more young than did clutches of four eggs. It is suggested that the major limiting factor on clutch size is food availability but the decreased hatching success of any remaining eggs once hatching has started is also a contributing factor.     

Discrepancy between factors affecting nestling growth and survival and maternal success in Common Grackles

ABSTRACT Multiple factors potentially affect nestling survival and maternal reproductive success. However, little is known about the relative importance of different factors when operating simultaneously or whether the same factors are important for nestlings and their mothers. We determined the effect of hatching asynchrony, individual egg size, mean egg size, nestling sex, and clutch initiation date on the survival of individual nestlings and on maternal reproductive success in Common Grackles (Quiscalus quiscula) from 2004 to 2006 in central Illinois. Factors most important to maternal success differed from those important for individual nestling growth and survival. Hatching asynchrony had the greatest within‐nest influence on the fate of nestlings; the earlier a nestling hatched relative to siblings, the greater its mass and likelihood of fledging. Clutch size had the greatest influence on maternal reproductive success, with females with larger clutches fledging more young. Thus, both nestling survival and maternal success were largely determined by a single, albeit different, factor. A possible explanation for the apparent unimportance of most factors we measured in determining maternal success is that we did not consider variation among females. Individual variation in maternal attributes such as condition, size, age, experience, or mate quality may result in females tailoring clutch attributes (i.e., egg size, sex, and degree of hatching asynchrony) in ways that allow them to maximize their reproductive success. The discordance between factors that benefited mothers versus their offspring illustrates the importance of considering the maternal consequences of any factor that appears to affect offspring survival. Factors that increase the mass and survival of some offspring may not result in increased maternal reproductive success.     

ESTABLISHMENT OF WEIGHT HIERARCHIES IN THE BROODS OF HOUSE MARTINS DELICHON URBICA

Nestling birds may differ in size and weight on the first day a clutch is fully hatched, mainly because eggs within clutches hatch over a period of several days. This asynchronous pattern of hatching is usually thought to facilitate brood reduction when the food supply is unpredictably restricted. The purpose of the study reported here was to examine the contribution of egg-weight, clutch-size, hatching spread, food supply and season to weight differences in newly hatched broods of the House Martin. At laying, heavy eggs had a greater moisture and dry weight content than light eggs and immediately before hatching there was a correlation between initial egg-weight and the dry weight of embryo and yolk. Heavier clutches also tended to give rise to heavier hatchlings. There was, however, no correlation of fresh egg-weight with the dry weight of embryos alone and the relative dry weight of embryos in a clutch was dependent on laying sequence. Hatching spread (the number of days between the emergence from the egg of the first and the last hatchling of the clutch) was 0.75 ± 0.46 days for clutches of two and increased with the size of the clutch up to 1.80 ± 0.79 days for clutches of five. When food was scarce during laying, hatching spread was greater. Weight difference in newly hatched broods was correlated with hatching spread and moreover in multivariate analysis was also correlated with periods of food scarcity during laying. It was concluded that all examples of weight hierarchies among hatchlings should not be considered adaptive; in some cases they may be imposed by food scarcity. This can lead to mortality of the runs even if food is plentiful. When the weight hierarchy is not adversely accentuated by food scarcity it may function as previously suggested, to allow brood reduction. Alternatively, particularly among House Martins, it may spread out the peak food needs of individual nestlings thereby spreading the demand on the adults.     

Early maternal effects and antibacterial immune factors in the eggs,nestlings and adults of the barn swallow

Transfer of immune factors via the egg may represent a maternal adaptation enhancing offspring survival. Lysozyme is a major component of maternal antibacterial immunity which is transferred to the eggs in birds. In a population of barn swallows (Hirundo rustica), lysozyme activity declined during the prelaying and laying periods in females but not in males. Egg hatching failure decreased with maternal lysozyme activity. The first eggs in a clutch contained more lysozyme and produced nestlings with larger lysozyme activity when 5 days old than last‐laid ones. In a cross‐fostering experiment where brood size was manipulated, nestling origin but not post‐manipulation brood size affected lysozyme activity. Hence, maternal lysozyme varies during the breeding season and may differentially enhance antibacterial immune defence of the eggs and nestlings in relation to laying order. These findings suggest that offspring innate immunity is influenced by early maternal effects.     

The breeding biology of the Dalmatian Pelican Pelecanus crispus

The breeding biology of the Dalmatian Pelican Pelecanus crispus , a vulnerable bird species in the Palaearctic, has been studied for 7 years at Lake Mikri Prespa, a continental wetland and Tsoukalio lagoon, a coastal wetland within the Amvrakikos Gulf. The two colonies showed stability, with fluctuations in the number of breeding attempts each year varying by about 30% over a period of 7 years. The date of arrival at the breeding sites and the date of laying of the first egg varied between mid-February and mid-March. The egglaying period (including renesting) varied between 18 and 114 days between years. The annual average clutch size varied between 1.60 and 1.94 eggs per nest. The incubation period averaged 31.4 ± 1.4 days. The overall hatching success varied from 36% to 70%. Egg losses were mainly due to nest abandonment, infertile eggs and eggs rolled from the nests. The Dalmatian Pelican chicks took 11–12 weeks to fledge. Nestling mortality was very low in contrast to other species of pelican. Such a low nestling mortality explains why the breeding success each year is largely explained by the hatching success.     

Costs of large communal clutches for male and female Greater Rheas Rhea americana

The breeding system of the Greater Rhea Rhea americana is almost unique among birds as it combines harem polygyny and sequential polyandry, with communal egg-laying and uniparental male care. In this species, large communal clutches (more than 30 eggs) are rare and have a lower hatching success than smaller clutches. Here we analyse the proximate causes of hatching failures and the costs of large communal clutches (and therefore the costs of extensive polygyny) for males and females. We evaluated if length of the nesting period, egg viability, egg losses during incubation and male parental activity at the nest were affected by clutch size. We also evaluated if chicks hatched from large clutches have a lower survival during the first 2 months after hatching. Large clutches had longer nesting period and lower hatching success, mainly as a result of bacterial contamination of the eggs and increased hatching asynchrony. In addition, large clutches tended to lose more eggs as a result of accidental breakage or predation. Male activity at the nest and chick survival were not related to clutch size. Low hatching success, nest predation risk and energetic costs associated with large clutches penalize females that join large harems and males that accept additional eggs into the nest.     

4. A FIELD NATURALIST'S PEREGRINATIONS. BIRD NOTES FROM A NORTHERN SECTOR OF SOUTHERN RHODESIA—Part III

Boyer, H. J. 1988. Breeding biology of the Dune Lark. Ostrich 59:30-37.

The peak of the breeding season of the Dune Lark Mirafra erythrochlamys occurred in January and February and was not dependent on rainfall. Most nests were domed, although one undomed nest was recorded. Ninety-one percent of clutches were of two eggs (mean = 1,9; range 1–2; n = 11). The eggs are described and measurements given. Incubation, by the female only, began with the laying of the second egg, and hatching occurred after 13–14 days. Growth and development of nestlings are described. The young left the nest after 12–14 days, and post-nestling parental care lasted for approximately one month. Sixty-one percent of eggs hatched. and 28% produced young which successfully left the nest. Most losses of eggs and young were the result of predation.     

The cost of incubation in relation to clutch-size in the Collared Flycatcher Ficedula albicollis

This study examines the importance of avian incubation costs as determinants of clutch-size variation by performing clutch-size and brood-size manipulations in the same population of Collared Flycatchers Ficedula albicollis during the same breeding season. In 2 5 cases when three or more clutches of the same size were completed on the same day, we moved two eggs on the day after the last egg had been laid from one randomly selected clutch (C) to another (C) and moved two other eggs from this to a third clutch (C⁺). In 20 other cases of simultaneously completed clutches of the same size, we moved two randomly selected young from one brood to a second and from that moved two other young to a third (B, B and B⁺groups). Most females were weighed the day after completion of the clutch and 1–4 days before hatching of the young, and some of them also 10–14 days after hatching of the young. We measured the daily energy expenditure of females incubating manipulated clutches of 4, 6 and 8 eggs by means of the doubly-labelled water (D₂¹⁸O) technique and also recorded their nest attendance. Hatching success of fertilized eggs was reduced in the enlarged clutches compared with control and reduced clutches. Females expired on average 3142.6 ml CO₂ and expended 78.6 kJ per day while incubating, which corresponds to a metabolic intensity of 3.3 times BMR. Daily energy expenditure increased with clutch-size due to higher costs while incubating, and not because of changed activity patterns. There were no significant differences in length of incubation, female mass or mass changes between phases for the C, C and C⁺groups. In both the C and B groups, enlarged broods produced significantly more fledged young than control broods, and those significantly more than reduced broods. Fledgling tarsus-length and mass did not differ significantly between treatments in either the C or B groups. There was no significant difference in breeding success between clutch and brood manipulations. In this season, incubation costs did not entail significant fitness losses, expressed either as fledgling production or female condition. Also, control females could have raised more young to fledging age than they did with no apparent costs.     

Annual and seasonal reproductive trends in the Lesser Spotted Woodpecker Dendrocopos minor

Annual and seasonal variation in reproductive timing and performance were studied in a population of the Lesser Spotted Woodpecker Dendrocopos minor over 10 years in southern Sweden. The median laying date of the first egg varied by up to 17 days between years, being generally larger than the variation of laying dates within years. Neither clutch size, brood size in successful nests, fledging success in successful nests nor mean nestling weight differed significantly between years. There was no trend for mean clutch size to vary between early and late years. In spite of a more than threefold variation in population size, no reproductive variable demonstrated an apparent density-dependence. Within the season, clutch size declined steeply with increasing clutch initiation date, whereas fledging success and nesting success did not, leading to a trend in brood size almost identical to the trend in clutch size. The survival prospects of fledged young declined with increasing clutch initiation date, and it is argued that the clutch size laid is a strategic adjustment to laying date. Out of 124 breeding attempts, 34% did not produce fledged young. In 9% of the breeding attempts, pairs laid no eggs. At least 20% of the breeding attempts failed after egg-laying. The most common cause of breeding failure was loss of the breeding partner followed by nest abandonment (40% of the failures). Only 16–28% of the failures were due to predation on the nest. Most complete failures, and also partial losses from nests, occurred at the early breeding stages. It is argued that the early nestling phase may be a critical stage, which the woodpeckers adjust to coincide with the seasonal food peak, explaining the strikingly late breeding season compared with other non-migrant species.     

Reduced immunocompetence of nestlings in replacement clutches of the European magpie (Pica pica)

Laying date is one of the most important determinants of reproductive success and recruitment probability in birds. Late breeders usually fledge fewer chicks than individuals with earlier breeding dates, and fledglings produced late in the season have high mortality rates. Food availability and nestling mass have been evoked as the principal mechanistic links between laying date and offspring survival. Here we suggest that another factor may actually account for the difference in survival rate between early and late offspring: immunocompetence. We predicted that nestlings produced later in the season or in replacement clutches should have lower immune responses when challenged with an antigen, than early nestlings or nestlings produced in first clutches. This hypothesis was tested in a population of magpies (Pica pica), in which we experimentally induced breeding failure in a group of nests and compared the immune response of nestlings in replacement clutches with the immune response of first clutch nestlings. Cellular immune response, as measured by wing web swelling (a correlate of T-lymphocyte production after injection of phytohaemagglutinin-P), significantly decreased with hatching date and was significantly lower in nestlings of replacement clutches. Furthermore, coefficients of intraclutch variation in immune response were higher in nestlings of replacement clutches. This experiment demonstrates an inverse relationship between immune responsiveness and breeding date, and reduced recruitment probability of late nestlings may be a direct consequence of their inability to cope with parasites.     

Hatching asynchrony that maintains egg viability also reduces brood reduction in a subtropical bird

In birds, hatching failure is pervasive and incurs an energetic and reproductive cost to breeding individuals. The egg viability hypothesis posits that exposure to warm temperatures prior to incubation decreases viability of early laid eggs and predicts that females in warm environments minimize hatching failure by beginning incubation earlier in the laying period, laying smaller clutches, or both. However, beginning incubation prior to clutch completion may incur a cost by increasing hatching asynchrony and possibly brood reduction. We examined whether Florida scrub jays (Aphelocoma coerulescens) began incubation earlier relative to clutch completion when laying larger clutches or when ambient temperatures increased, and whether variation in incubation onset influenced subsequent patterns of hatching asynchrony and brood reduction. We compared these patterns between a suburban and wildland site because site-specific differences in hatching failure match a priori predictions of the egg viability hypothesis. Females at both sites began incubation earlier relative to clutch completion when laying larger clutches and as ambient temperatures increased. Incubation onset was correlated with patterns of hatching asynchrony at both sites; however, brood reduction increased only in the suburbs, where nestling food is limiting, and only during the late nestling period. Hatching asynchrony may be an unintended consequence of beginning incubation early to minimize hatching failure of early laid eggs. Food limitation in the suburbs appears to result in increased brood reduction in large clutches that hatch asynchronously. Therefore, site-specific rates of brood reduction may be a consequence of asynchronous hatching patterns that result from parental effort to minimize hatching failure in first-laid eggs. This illustrates how anthropogenic change, such as urbanization, can lead to loss of fitness when animals use behavioral strategies intended to maximize fitness in natural landscapes.     

Yolk testosterone and estradiol variation relative to clutch size, laying order and hatching asynchrony in Common Grackles

Maternal effects are typically thought to enhance rather than reduce offspring performance, but asynchronous hatching (ASH) in birds typically produces a size hierarchy within a clutch that frequently reduces the growth and survival of nestlings from eggs that hatch later. Given that yolk steroids can significantly affect offspring phenotype and that in many species the levels of yolk steroids have been found to increase with laying order, the maternal transfer of steroids to egg yolk has been proposed as a mechanism for females to offset the deleterious effects of ASH. To test this hypothesis, we determined whether yolk steroids varied with laying order or clutch size in Common Grackles (Quiscalus quiscula). Because ASH varies with clutch size (hatching span averages 48 h in five-egg clutches, 24 h in four-egg clutches) and regularly results in the starvation of later hatched nestlings, we predicted: (1) testosterone and 17?-estradiol levels should increase with laying order in both clutch sizes to mitigate the negative effects of ASH on last-hatched nestlings, and (2) the increase should be greater in five-egg clutches due to more pronounced hatching asynchrony. Using a competitive-binding steroid radioimmunoassay, we found no systematic variation in either testosterone or estradiol levels relative to laying order or clutch size. In the absence of evidence that yolk steroids interact adaptively with ASH, research must look elsewhere for potential benefits that might compensate for the costs these steroids impose on nestlings.     

The breeding biology of the Pacific Swallow Hirundo tahitica in Malaysia

The breeding biology of the Pacific Swallow was studied in Malaysia. Time-budgets and preliminary energy-budgets were calculated for different stages of the breeding cycle. Breeding was seasonal, the first eggs were laid in the first week of March from 1978 to 1982. The nest was a mud cup built under an overhang, often on man-made structures over water. The mean clutch size was 2.98 eggs. So more than two successful clutches were ever raised, although up to four sets of eggs can be laid if clutches are lost. The incubation period was 16.2 days and the nestling period 19–21 days. Nestling weights showed the typical hirundine recession before fledging. The mean brood size was 2.32 and there was no evidence of undernourishment in larger broods. Nesting success was lower than for temperate hirundines but high for a tropical passerine. Incubation duties were carried out by the female alone but both parents fed the brood. The male never delivered more than 44% of the total feeds. Daily energy expenditure varied from 3.44–4.9×BMR depending upon the stage of the breeding cycle.     

荒漠伯劳的繁殖及雏鸟生长发育

2006～2007年对新疆石河子市荒漠伯劳(Lanius isabellinus phoenicuroides)的巢、卵及雏鸟的生长发育状况进行了研究.结果表明,荒漠伯劳窝卵数平均5.67枚,孵卵期17 d,育雏期15 d.育雏主要由雌鸟担任.采用Logistic方程对雏鸟发育过程中主要生长指标的生长方程进行了曲线拟合,相关指标生长方程的拟合度均在0.99以上.