Kelp gulls, Larus dominicanus (Aves: Laridae), breeding in Keller Peninsula, King George Island, Antarctic Peninsula

We examined the distribution, abundance and density of the Kelp Gull, Larus dominicanus (Lichtenstein, 1823), at Keller Peninsula on two occasions during the breeding season of 2007-2008 (once for incubation and once for chick stages) and compared our results with previously published data. We present information on the number of eggs, incubation success, and initial development of L. dominicanus chicks in the studied sites. The abundance and density of the species has remained statistically similar in Keller Peninsula over the last 30 years (since 1978-1979). Although the abundance and density were almost unchanged, we recorded alterations in the occupation of the breeding areas by L. dominicanus, mainly the abandonment of breeding sites in the eastern portion of Keller Peninsula. The results of the present study compared with similar previous investigations on the abundance of L. dominicanus indicate that the populations have been in equilibrium over the years.

Broad reduction and adoption in ring-billed gulls (Larus Delaworensis): the potential for inergenerational conflict

Patterns of intra-clutch egg size variation and intra-clutch hatch intervals in the Ring-billed gull (Larus delawarensis) were documented during the peak nesting period of two consecutive breeding seasons, at a colony near Port Colborne, Ontario. Egg size decreased with laying order; third laid eggs were significantly smaller than first laid eggs. Hatching of the third egg was delayed from that of first and second eggs. Intraclutch egg size differences established initial size disparities among chicks at hatch. Hatch intervals further exaggerated size disparities during the early post brood completion period. Competitive asymmetries among chicks were associated with increased mortality rates among third hatched chicks despite the lack of evidence of a sibling feeding hierarchy. Fledging success in 1987 was greater than in 1988. A "brood reduction strategy" appears to have enabled parents in 1987, to obtain an extra unit of reproductive fitness, while in 1988 parents were often unable to raise the entire brood and third chicks likely represented insurance reproductive value. Experimental broods (1988) were created in which hatch intervals were double those of natural intervals. The size disparities among chicks were significantly greater than in control broods, and the pattern of mortality among chicks suggested that first chicks benefited at a cost to second and third chicks. Parents of peak experimental broods achieved a fledging success rate similar to that of control broods. Characteristics of chick adoptions were also recorded. In each study year, 9 chicks abandoned their natal territories, 6 of which were adopted. Chicks consistently established themselves into broods where they were older than resident chicks. No direct evidence of cost to foster parents, or benefits to adopted chicks was obtained, although fledging success of adopted chicks was high.

Seasonal variation in hatching pattern and chick survival in the ring-billed gull Larus delawarensis

The general objective of my study was to monitor proximate causes and seasonal patterns of hatching asynchrony and chick survival in the Ring-billed Gull (Larus delawarensis). Two different plots were set up at a Ring-billed Gull colony near Port Colborne, Ontario in the summer of 1992. One group was from 'peak' nesting pairs (clutches initiated between 15 April and 1 May); a second group was from 'late' nesting pairs (clutches initiated between 9 .. 22 May). Despite equal intra-clutch egg laying intervals between the peak and late periods, intra-clutch hatching intervals lengthened as the season progressed (ie. hatching became more asynchronous). Clutches from both periods were monitored for nocturnal attendance and brood patch development of parents was monitored during the egg laying period. Late nesters were characterized by an absence of nocturnal desertion, substantial brood patch defeatheration at clutch initiation and a reduction in the number of chicks fledged per pair. Chick survival to 25 days (taken as fledging) reflected patterns of chick mass at brood completion and five days post-brood completion, in peak clutches. In late clutches, survival was poor for all chicks and, was partially independent of hatching order, due in part to stochastic events such as Herring Gull predation and adverse weather. In both the peak and late periods, last-hatched C-chicks realized the poorest survival to fledging among brood mates. An artificial hatching pattern (manipulated synchrony) and an artificial hatching order were created, in three-chick broods, through a series of egg exchanges. In peak and late clutches manipulated to hatch synchronously (s; 24 h): C-chick survival to fledging did not differ from the survival of A- and B-chicks, in the peak period. In the late period, the survival of C-chicks was significantly lower than that of A-chicks. In peak clutches manipulated such that chicks from last-laid eggs (C-chicks) hatched 24 h - 48 h ahead of the A- and B- chicks, C-chick survival was greater than in controls. Within those broods, C-chicks survived better on average than both A- and B- chicks.

Fatores físicos e idade da matriz na incubação de ovos de codornas japonesas (Coturnix coturnix japonica)

Pós-graduação em Zootecnia - FCAV

Incubation of turtle eggs at different temperatures: Do embryos compensate for temperature during development?

Freshwater turtle eggs are normally subjected to fluctuations in incubation temperature during natural incubation. Because of this, developing embryos may make physiological adjustments to growth and metabolism in response to incubation at different temperatures. I tested this hypothesis by incubating eggs of the Brisbane river turtle Emydura signata under four different temperature regimes, constant temperatures of 24 degrees C and 31 degrees C throughout incubation, and two swapped-temperature treatments where incubation temperature was changed approximately halfway through incubation. Incubation at 31 degrees C took 42 d, and incubation at 24 degrees C look 78 d, with intermediate incubation periods for the swapped-temperature treatments. Hatchling mass, hatchling size, and total oxygen consumed during development were similar for all incubation regimes. The pattern of oxygen consumption during the last phase of incubation as reflected by rate of increase of oxygen consumption, peak oxygen consumption, and fall in oxygen consumption before hatching was determined solely by the incubation temperature during the last phase of incubation; that is, incubation temperature during the first phase of incubation had no influence on these factors. Thus there is no evidence of temperature compensation in growth or development during embryonic development of E. signata eggs.

Incubation of eggs of the Australian broad-shelled turtle, Chelodina expansa (Testudinata : Chelidae), at different temperatures: effects on pattern of oxygen consumption and hatchling morphology

Incubation temperature influences embryonic development and the morphology of resultant hatchlings in many species of turtle but few studies have addressed its effect on oxygen consumption and total embryonic energy expenditure. Eggs of the Australian broad-shelled river turtle, Chelodina expansa, were incubated at constant temperatures of 24 degrees C and 28 degrees C to determine the effect of temperature on oxygen consumption, embryonic energy expenditure and hatchling morphology. All embryos at both incubation temperatures experienced a period of developmental diapause immediately after oviposition. Once this initial diapause was broken, embryos underwent a further period of developmental arrest when the embryo was still very small and had minimal oxygen consumption (

Incubation of Rigid-shelled Turtle Eggs: do Hydric Conditions Matter?

Rigid-shelled eggs of the broad-shelled river turtle Chelodina expansa were incubated at 28 degreesC in wet (-100 kPa), intermediate (-350 kPa) and dry (-750 kPa) conditions. Incubation period was influenced by clutch of origin, but was independent of incubation water potential. Rates of water gained from the environment and pre-pipping egg mass were influenced by incubation water potential - eggs incubating at higher (less negative) water potentials absorbing more water from their environment. Hatchlings from wet conditions had greater mass but a smaller amount of residual yolk than hatchlings from dry conditions and it is suggested that the amount of yolk converted to tissue is influenced by the amount of water absorbed by the egg during incubation. Water content of yolk-free hatchlings from the -100-kPa treatment was greater than those from the 350-kPa and -750-kPa treatments, but the water content of residual yolks was similar across all hydric conditions.

Effects of Incubation Temperature and Relative Humidity on Embryonic Development in Eggs of Red-Winged Tinamou (Rhynchotus rufescens).

This study was conducted to assess the effects of incubation temperature (34 C, 36[degree]C and 38[degree]C) and relative humidity (RH, 50% and 60%) on egg weight loss, embryo mortality, hatchability, incubation time and chick weight in eggs from red-winged tinamou. The eggs were placed in incubators that were operated at 34[degree]C, 36[degree]C, or 38[degree]C and 50% or 60% RH (mean wet bulb temperatures of 28[degree]C and 30[degree]C, respectively) from day 1 to hatching. Each treatment had two replicate groups of 30 eggs each. Hatchability varied with incubation temperature and RH and was highest for eggs incubated at 36[degree]C and 60% RH and lowest for eggs incubated at 38[degree]C. Early, intermediate and late embryo mortality were highest at 38[degree]C, 38[degree]C/50% RH, and 50% RH, respectively. Incubation period was longest at 34[degree]C and shortest at 38[degree]C/50% RH. Present results show the highest hatchability of red-winged tinamou eggs after incubation at 36[degree]C and 60% RH; highest embryo sensitivity to high temperature in the early period of incubation (1 to 7 days), to high temperature and low RH in the second period of incubation (8-14 days) and to low RH in the late period of incubation (after 15 days) and shortest incubation period with increasing temperature and RH.

Hematological and incubation parameters of chicks from young breeders eggs: Variation with sex and incubation temperature

This experiment analyzed the effect of sex and incubation temperature on daily mass loss and eggshell conductance, embryo mortality rates, incubation duration, hematological parameters and body, liver, heart and bursa weights of neonatal chicks from young breeders. The daily mass loss was higher at incubation temperature of 39°C. The eggshell conductance rate increased with the temperature. The total and partial duration of incubation were lower for eggs incubated at 39°C. The time taken by the chick to leave the eggshell did not differ below and above the thermoneutral temperature. The total and intermediate embryo mortality rates increased with the incubation temperature, whereas the early and late embryo mortality rates were higher at incubation temperature of 39°C. Sex did not influence the analyzed parameters, while the incubation temperature did not affect the body and bursa weight and the erythrocytes characteristics. The liver weight of chicks incubated at 36°C was higher than the incubated at 39°C, however there were no differences among the liver weight from chicks incubated at 36 and 39°C and those incubated at 37.5°C. The number of heterophils and the heterophil/lymphocyte ratio (H/L ratio) increased following the temperature, whereas the number of lymphocytes decreased at high temperatures. The other leukocyte parameters did not suffer influence of temperature. Males and females presented similar response to variation of incubation temperatures (36, 37.5 and 39°C) and demonstrated higher sensibility to temperatures above the thermoneutral. Moreover, temperatures below the thermoneutral demonstrated to be better for improvement of hatchability and development of chicks from light eggs. © Asian Network for Scientific Information, 2010.

Artificial incubation of some upland game birds' eggs,

"References": p. 42. "Bibliography of books and bulletins on the propagation of pheasants, grouse and quail": p. 43-44.

Influence of egg pre-storage heating period and storage length on incubation results

This experiment aimed at evaluating the influence of different heating times of settable eggs of Cobb 500 (R) broiler breeders before submitting them to different storage periods on egg weight loss, embryo mortality, and hatchability. A total number of 1,980 eggs were distributed in a completely randomized experimental design with a 3 x 3 factorial arrangement, comprising nine treatments with 22 replicates of 10 eggs each. The following factors were analyzed: pre-storage heating periods (0, 6, 12 hours at 36.92 degrees C) and storage periods (4, 9, 14 days at 12.06 degrees C). After storage, eggs were incubated under usual conditions, and were transferred to the hatcher at 442 hours of incubation. Eggs were weighed before heating, incubation, and transference to determine weight loss. Partial hatchability was determined at 480 hours, and total hatchability at 498 hours of incubation. Embryo mortality was determined in non-hatched eggs. It was concluded that heating eggs for six hour before storage improves incubation results as it decreases incubation length and late embryo mortality, therefore its use can be indicated in commercial operations. Storing eggs for 14 days and pre-heating for 14 days and pre-heating for 12 hours severely impair incubation results, and therefore are not recommended.

Effects of incubation temperature on the energetics of embryonic development and hatchling morphology in the Brisbane river turtle Emydura signata

Incubation temperature and the amount of water taken up by eggs from the substrate during incubation affects hatchling size and morphology in many oviparous reptiles. The Brisbane river turtle Emydura signata lays hard-shelled eggs and hatchling mass was unaffected by the amount of water gained or lost during incubation. Constant temperature incubation of eggs at 24 degrees C, 26 degrees C, 28 degrees C and 31 degrees C had no effect on hatchling mass, yolk-free hatchling mass, residual yolk mass, carapace length, carapace width, plastron length or plastron width. However, hatchlings incubated at 26 degrees C and 28 degrees C had wider heads than hatchlings incubated at 24 degrees C and 31 degrees C. Incubation period varied inversely with incubation temperature, while the rate of increase in oxygen consumption during the first part of incubation and the peak rate of oxygen consumption varied directly with incubation temperature. The total amount of oxygen consumed during development and hatchling production cost was significantly greater at 24 degrees C than at 26 degrees C, 28 degrees C and 31 degrees C. Hatchling mass and dimensions and total embryonic energy expenditure was directly proportional to initial egg mass.

Uncommon mechanism of egg incubation in the endemic Southern hermit crab Loxopagurus loxochelis: how is this phenomenon related to egg production?

The aim of the present work was to characterize the egg production of Loxopagurus loxochelis. A total of 71 ovigerous females were obtained, 28% of which were simultaneously incubating eggs at different developmental stages. This phenomenon can be the result of incomplete fertilization, or may represent a rapid gonadal cycle by this species in this area, which is, to our understanding, the best explanation of this phenomenon. Egg volume decreased 25.6% during the incubation period. The reproductive output based on dry and wet weight was 6.8 and 19.3%, respectively. Water was the prevailing component of the eggs, representing 86.0% of the total weight at initial stage, increasing to 95.1% at the final stage. Ash content increased at the same time as a decrease in the organic content occurred, indicating the consumption of yolk and absorption of salts from the water medium. In conclusion, we hypothesized that this population has the capacity to copulate and deposit another brood even before the release of the larvae from the previous one, intensifying the reproductive effort of these hermit crabs as a strategy of adaptation in a region considered the northern limit of the geographical distribution of this species.

Incubation temperature, energy expenditure and hatchling size in the green turtle (Chelonia mydas), a species with temperature-sensitive sex determination

Eggs from the Heron Island, Great Barrier Reef, nesting population of green turtles (Chelonia mydas) were incubated at all-male-determining (26 degreesC) and all-female-determining (30 degreesC) temperatures. Oxygen consumption and embryonic growth were monitored throughout incubation, and hatchling masses and body dimensions were measured from both temperatures. Eggs hatched after 79 and 53 days incubation at 26 degreesC and 30 degreesC respectively. Oxygen consumption at both temperatures increased to a peak several days before hatching, a pattern typical of turtle embryos, and the rate of oxygen was higher at 30 degreesC than 26 degreesC. The total amount of energy consumed during incubation, and hatchling dimensions, were similar at both temperatures, but hatchlings from 26 degreesC had larger mass, larger yolk-free mass and smaller residual yolks than hatchlings from 30 degreesC. Because of the difference in mass of hatchlings, hatchlings from 30 degreesC had a higher production cost.