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1.
The breeding biology of the Red Kite Milvus milvus is still little known in the southern part of its range (Mediterranean), despite recent conservation concerns and major declines in most insular populations (Sicily, Sardinia and Balearics). We report here on the breeding biology of the Red Kite in Corsica in 1996–99 and on recent population trends there. In a 42‐km2 study area located in the northwest of the island (Balagne region), breeding density was locally high (1.17–1.78 breeding pairs/km2). Breeding dispersion ranged from loosely colonial to dispersed, with average nearest‐neighbour distance of 444 ± 316 m (range 50–2000) (all data as means ± sd). Kites established breeding territories in January–February, and 92.4% of territorial pairs laid a clutch (n = 238). Laying took place between February and May (mean lay date: 27 March ± 16 days, n = 147). Clutch size averaged 2.44 ± 0.71 (1–5 eggs, n = 96), hatching success 66.9% and fledging success 78.6%. Productivity averaged 1.33 ± 0.88 young per breeding attempt (n = 221) and 1.65 ± 0.65 young per successful breeding attempt (n = 173). Overall breeding success was 51.4 ± 38.0% (n = 88). We describe the growth of young (wing, weight, tarsus and bill) and show a marked seasonal decline in clutch size and breeding performance, with pairs laying earlier producing larger clutches and being more successful than later breeding pairs. Unlike most other insular Mediterranean Red Kite populations that have recently declined, the breeding population in the northwest of Corsica, which accounts for c. 25% of the whole island population, increased from 25 to 35 pairs in 1989 to a maximum of 80–90 pairs in 1997. This increase was probably related to the lack of persecution and a local increase in abundance of Rabbits Oryctolagus cuniculus, following their introduction in the late 1970s, which provided an important feeding resource for Kites. Finally, we compare our results with those from other Red Kite populations studied in Europe. We found that there is a latitudinal gradient in laying date and productivity across Western Europe populations, but no evidence of an insular syndrome in the Corsican population.  相似文献   

2.
To better understand breeding conditions to promote reproduction in captive kori bustards, fundamental endocrine studies measuring fecal androgen metabolites in male and female kori bustards were conducted. Feces collected weekly from males and females were analyzed for testosterone using enzyme‐linked immunoassay. Results from adult males (n = 5), adult females (n = 10), immature males (n = 10), and immature females (n = 10) revealed seasonally elevated testosterone concentrations in fertile, but not nonfertile adult males and females (P > 0.05). Adult females that were not maintained in a breeding group, or that did not produce eggs, did not demonstrate increases in testosterone compared to egg laying counterparts. In males, but not females, seasonal testosterone increases were accompanied by weight gain. Peaks in male fecal androgen metabolites ranged from 10‐ to 22‐fold higher than nonbreeding season (181.5 ± 19.1 vs. 17.0 ± 0.94 ng/g; P < 0.05). Mean breeding season values for adult males were 83.6 ± 6.1 ng/g vs. nonbreeding season values of 12.3 ± 0.73 ng/g (P < 0.05). In females, average breeding season testosterone concentrations were approximately 4‐fold higher than nonbreeding season (55.9 ± 6.0 vs. 14.5 ± 1.8 ng/g), with peaks 10‐ to 30‐fold higher. Results show that noninvasive fecal androgen metabolite analysis can provide a means of predicting fertility potential of male and female kori bustards and might be utilized to assess effects of modifying captive environments to promote reproduction in this species. Zoo Biol. 32:54‐62, 2013. © 2012 Wiley Periodicals, Inc.  相似文献   

3.
The purpose of this study was to determine critical components of the life history including otolith age validation, growth estimation, and reproductive characteristics for southern kingfish Menticirrhus americanus. A total of 2233 southern kingfish were collected from March 2009 to December 2010. Ages were estimated and validated using thin‐sectioned otoliths. Marginal increment analysis showed a single annulus was deposited once a year between April and May. Growth was significantly different (P < 0.0001) between sexes Linf = 418.97 ± 16.58 mm, k = 0.29 ± 0.03, t0 = ?1.30 ± 0.10 for females and Linf = 290.74 ± 6.93 mm, k = 0.52 ± 0.05, t0 = ?1.08 ± 0.11 for males. Southern kingfish spawn from March to August with a peak spawn in April. Based on evidence of multiple oocyte maturation stages and post‐ovulatory follicles (POFs) southern kingfish are multiple spawners exhibiting indeterminate fecundity. Spawning frequency for females ranging from 222 to 351 mm TL (age 1–5) was estimated as one spawning event every 2.0–4.2 days with up to 6 million total ova produced per spawning season per female.  相似文献   

4.
ABSTRACT

Capsule: The mating system of the Brown Accentor Prunella fulvescens in the high altitudes of the Tibeta plateau is mainly monogamous but polyandry was recording in 9.7% of breeding groups.

Aims: To describe the poorly known breeding biology of Brown Accentors in the high-altitude environment of the northeastern Tibet plateau.

Methods: Individually colour-ringed birds were observed during two breeding seasons. Biometrics were recorded for breeders, and reproductive variables were quantified.

Results: Brown Accentors were territorial during the breeding season and were resident year-round. Most groups (90.3%, n?=?31 groups) were socially monogamous and the remainder (9.7%) were polyandrous, with two males sharing a female’s territory. Mean group size was 2.1 adults and the population adult sex ratio was 52% male. The birds raised a single brood during the breeding season. Nests were invariably located in Sea Buckthorn Hippophae rhamnoides. Eggs were laid between late June and late July, and mean clutch size was 3.4?±?0.6 (SD) eggs. Incubation was undertaken by the female and lasted 12.9?±?0.9 (SD) days. Both sexes provisioned young in the nest for 13.9?±?1.2 (SD) days. Females provided significantly more feeding visits than did males. Brood size at estimated fledging dates averaged 2.2?±?0.7 (SD) nestlings. Forty-five per cent of nesting attempts (n?=?37) fledged at least one nestling.

Conclusions: Like other species in the family Prunellidae, the Brown Accentor exhibits remarkable variation in its mating system.  相似文献   

5.
This study concerns the reproductive strategy of the freshwater fish, Leporinus piau, native to the Brazilian semi‐arid region. The hypothesis of this work predicts that the species would spawn during the rainy season, presenting a seasonal reproductive strategy. The study investigated the structure of total body length and body mass, sex ratio, body size at first sexual maturity, developmental stages of gonads, fecundity, gonadosomatic index (GSI), condition factor (K) and the spawning season of L. piau. Twelve monthly samplings (mean n = 18) were carried out in 2009 and environmental parameters such as rainfall, temperature, pH, electrical conductivity and concentration of dissolved oxygen of water were registered. The sampled population of L. piau (n = 211) showed a slight predominance of males (55%), but with larger and heavier females. First sexual maturation in males occurred earlier (16.5 cm total length) than in females (20.5 cm total length). The species is a total spawner with an average fecundity of 55 000 mature oocytes. Rainfall (225 ± 7.2 mm) and concentration of dissolved oxygen (8.5 ± 0.2 mg L?1) acted as influential factors during the spawning season. The monthly GSI shows that spawning starts when the rainy season is at its maximum and ends synchronously (females r = 0.91; males r = 0.89) with the end of the rainy season. L. piau presents a seasonal reproductive strategy with high reproductive output, providing a population increase and exploitation of the environmental resources.  相似文献   

6.
The population parameters of stargazer (Uranoscopus scaber Linnaeus, 1758) were studied regarding age composition, sex ratio, growth, survival and mortality rates, and the exploitation rate in the southeastern Black Sea near the coast of Turkey during the 2011–2012 fishing season. According to ageing analysis of the samples, age group 1 is the most abundant (47.76%), followed by age 2 (41.04%), age 3 (9.33%), age 0 (1.12%) and age 4 (0.75%). Mean totals as well as total lengths and weights for males and females were 14.5 ± 0.22 cm and 12.9 ± 0.19 g, 16.6 ± 0.24 cm and 62.1 ± 2.76 g, and 37.2 ± 1.92 cm and 87.1 ± 3.88 g, respectively. The mean condition factor was K = 0.0167, while the sex ratio was 53.98% female, 38.75% male and 7.27% immature. Length‐weight, age‐length and age‐weight equations were W = 0.014 × L3.059, L(t)=44.5*[1?e?0.148*(t +1.242)] and W(t)=1544.4*[1?e?0.148*(t + 1.242)]3.059, respectively. The computed survival rate (S), instantaneous total mortality rate (Z), annual mortality rate (A), natural mortality rate (M) and fishing mortality rate (F) were S = 28.94%, Z = 1.24 year?1, A = 71.06%, M = 0.26 year?1 and F = 0.98 year?1, respectively. The exploitation rate was 0.79, which is above the optimum exploitation levels.  相似文献   

7.
Tracking small passerines using miniaturized location tags is a rapidly expanding field of study. In a 1‐year study, we tested whether there were any short‐ or longer‐term effects of fitting geolocators weighing 3% of body mass on male Pied Flycatchers Ficedula hypoleuca. In the deployment year, we compared adult provisioning rates to nestlings, nestling growth and nest success between nesting attempts in which adult males were fitted with a geolocator, with control nests where males had the same capture history but were not tagged. We found no difference between treatments in provisioning effort by males or their associated female 2 days after geolocator fitting, in terms of nestling growth, subsequent brood reduction or nest success. Return rate, arrival date on territories, nest timing and breeding parameters were compared between tagged and untagged males in the following breeding season. We found no difference in return rate or arrival date, and no difference in nest timing, fecundity or outcome. Our study suggests that fitting lightweight tags to small passerines need not affect behaviour, breeding or apparent between‐year survival. However, tagging new species should still require assessment and comparison with well‐matched control cohorts, and it should be recognized that tag effects could vary between years and populations, mediated by environmental conditions.  相似文献   

8.
The Sociable Lapwing Vanellus gregarius is a critically endangered species, probably declining from 5000 pairs to 500 pairs in 11 years. Fieldwork was conducted at two sites in Kazakhstan, May–August 2004, to identify causes of the species’ decline. In total, 58 nests and a minimum of 36 broods in 16 colonies were found: colonies consisted of 1–8 nests that were on average 154 m apart, with 2.1 km between colonies. Although classified as biparental, the total proportion of time both parents spent incubating was low (77 ± 2% se, n = 13 nests). Daily survival rates (Mayfield method) were very low during incubation (0.943 ± 0.009 se) but high during the chick stage (0.986 ± 0.004 se); incubation and chick‐stage durations were found to be 28.5 and 29 days, respectively, so that the overall probability of any breeding attempt fledging chicks was 0.124 (0.055–0.274 95% confidence interval). A breeding attempt that produced fledglings, fledged 2.2 ± 0.2 se chicks (n = 26) on average. Observed productivity predicted the population decline over the last 11 years well (using the maximum number of nesting attempts per pair of 1.4 that could have occurred in this study, and assuming an adult and first‐year survival rate of 0.74 and 0.60, respectively, based on the means for Northern Lapwing Vanellus vanellus and Golden Plover Pluvialis apricalia). Nest survival during incubation (controlling for colony effects) may have been longer for nests in predominantly Artemisia rather than grass habitat. Mean nest survival for a colony was higher in areas with more bare ground and more nest predators, suggesting that predators were relatively unimportant in nest (egg or chick) mortality, but was lower in areas with high numbers of cattle, suggesting that trampling was important (64% of known‐cause nest failures, n = 11, were trampled). Nests were preferentially sited in areas of Artemisia, where there was greater dung abundance, and probably shorter vegetation, suggesting that highly grazed vegetation is important for nesting. Chicks preferentially selected areas with a lower percentage of bare ground and possibly taller vegetation, suggesting that more vegetated areas are important for chicks. The results suggest that low egg survival due to nesting in areas of high grazer density may be responsible for the Sociable Lapwing's decline. Although grazers may create suitable vegetation for initial nesting, if those grazers remain at high density as in anthropogenic systems then they may reduce nest survival, probably through trampling. Experimentally maintaining grazing early but reducing it later in the breeding season is the logical first step in managing the species to increase egg survival and so to increase productivity.  相似文献   

9.
Survival of tropical passerines is thought to be higher than those in northern temperate regions, but relatively few tropical studies have addressed this issue, particularly in tropical Asia. We examined factors that may have influenced the survival rate of a cooperatively breeding bird, the puff-throated bulbul (Alophoixus pallidus), in an evergreen forest in northeastern Thailand. These factors included year, season (breeding and non-breeding), sex, and presence of helper(s) in a family group. We present evidence of breeding season-dependent survival in a tropical passerine using an information theoretic approach based on both mark-recapture and resighting data collected during 6 years of study. Based on colour-banded adults the annual survival rate did not vary significantly among years (average = 0.85 ± 0.02 SE). The mean lifespan (MLS) for the population was 6.22 ± 4.38 SE years. Survivorship was lower during the breeding season (0.89 ± 0.02 SE) than during the non-breeding season (0.96 ± 0.02 SE). The MLS of males and females was 6.70 ± 7.73 SE and 5.87 ± 4.88 SE years, respectively. The annual survival rate we observed was high compared to the estimates of other tropical and temperate passerines, possibly due to the relatively stable climatic conditions in tropical latitudes and puff-throated bulbuls being generalists that exploit a wide range of food resources both in space and time.  相似文献   

10.
This experimental study was designed to clarify the relationship between cardiomyocyte apoptosis and tumour necrosis factor‐alpha (TNF‐α) expression, and confirm the effect of TNF‐α on cardiac dysfunction after coronary microembolization (CME) in mini‐pigs. Nineteen mini‐pigs were divided into three groups: sham‐operation group (n = 5), CME group (n = 7) and adalimumab pre‐treatment group (n = 7; TNF‐α antibody, 2 mg/kg intracoronary injection before CME). Magnetic resonance imaging (3.0‐T) was performed at baseline, 6th hour and 1 week after procedure. Cardiomyocyte apoptosis was detected by cardiac‐TUNEL staining, and caspase‐3 and caspase‐8 were detected by RT‐PCR and immunohistochemistry. Furthermore, serum TNF‐α, IL‐6 and troponin T were analysed, while myocardial expressions of TNF‐α and IL‐6 were detected. Both TNF‐α expression (serum level and myocardial expression) and average number of apoptotic cardiomyocyte nuclei were significantly increased in CME group compared with the sham‐operation group. Six hours after CME, left ventricular end‐systolic volume (LVESV) was increased and the left ventricular ejection fraction (LVEF) was decreased in CME group. Pre‐treatment with adalimumab not only significantly improved LVEF after CME (6th hour: 54.9 ± 2.3% versus 50.4 ± 3.9%, P = 0.036; 1 week: 56.7 ± 4.2% versus 52.7 ± 2.9%, P = 0.041), but also suppressed cardiomyocyte apoptosis and the expression of caspase‐3 and caspase‐8. Meanwhile, the average number of apoptotic cardiomyocytes nuclei was inversely correlated with LVEF (r = ?0.535, P = 0.022). TNF‐α‐induced cardiomyocyte apoptosis is likely involved in cardiac dysfunction after CME. TNF‐α antibody therapy suppresses cardiomyocyte apoptosis and improves early cardiac function after CME.  相似文献   

11.
ABSTRACT As tropical habitats continue to be cleared or degraded, obtaining basic information about the ecology of birds in intact habitats is essential for understanding their life histories. We studied the breeding biology of Orange‐breasted Trogons (Harpactes oreskios) and Red‐headed Trogons (H. erythrocephalus) in Khao Yai National Park in Thailand from 2003 to 2009. Nests were in excavated cavities in well‐rotted stumps or other tree parts. Mean cavity heights were 2.1 m (N= 19) for Orange‐breasted Trogons and 2.0 m (N= 49) for Red‐headed Trogons. Eggs were laid every other day. For Orange‐breasted Trogons, the mean clutch size was 2.4 ± 0.1 (SE) eggs (N= 17); incubation periods for two nests were 17 and 18 d, respectively, and the nestling period ranged from 12 to at least 14 d (N= 4). For Red‐headed Trogons, the mean clutch size was 2.6 ± 0.1 eggs (N= 48), the mean incubation period was 18 d (N= 9), and the mean nestling period was 13.4 d (N= 5). In both species, both males and females excavated nest sites, incubated eggs, and brooded and provisioned nestlings. Only females incubated and brooded at night, and males provisioned nestlings more than females. Breeding seasons lasted from January to March for Orange‐breasted Trogons, and from late February to July for Red‐headed Trogons. Mayfield estimates of nest success were 8% and 9% for Orange‐breasted and Red‐headed trogons, respectively. Unusual for cavity nesters, nest failure due to predation was high and nestling periods short. The low nesting success is typical of many other tropical species, but considerably lower than reported for some Neotropical trogons, possibly due to the unenclosed structure of the nests of these Asian trogons.  相似文献   

12.
Several environmental parameters related to the spawning season of the freshwater fish, Psectrogaster rhomboides were identified. The hypothesis predicts synchrony of the spawning season with the rainy period, presenting a seasonal reproductive strategy. This study investigated the total body length and body mass, sex ratio, body size at first sexual maturity, gonadosomatic index, condition factor, fecundity and reproductive period of P. rhomboides in the natural environment. Twelve monthly samplings (mean n = 20) were carried out from March 2009 to February 2010. Fish were captured using 4 cm diameter cast nets and environmental parameters such as rainfall, temperature, dissolved oxygen concentration, pH and electrical conductivity of the water were registered. The sampled population of P. rhomboides (n = 444) showed a sex ratio of 1 : 1. Females attained first sexual maturity at 15 cm total length and males at 15.3 cm total length. Spawning occurred from March to May, with high gonadosomatic index values during the rainy season. This species is a total spawner, with a mean fecundity of 6188 (±367) mature oocytes. P. rhomboides presents a seasonal reproductive strategy, providing a population increase and exploitation of the environmental resources during the rainy period. Rainfall (196.5 ± 4.9 mm) and the concentration of dissolved oxygen (7.82 ± 0.7018 mg L?1) were influential factors during the spawning season. Gonadosomatic index and the condition factor were negatively correlated during the gonadal development cycle of this species. The monthly gonadosomatic index values show that spawning begins when the rainy season is at its maximum and ends synchronously (females r = 0.9171; males r = 0.889) with the end of the rainy season.  相似文献   

13.
This study describes the reproductive biology of the Chinese minnow Hemiculterella sauvagei. The length‐weight relationship, sex ratio, spawning season, size at first maturity, and fecundity were analyzed based on 685 specimens collected from the Chishui River between July 2011 and July 2012. The relationship between standard length (SL) and body weight (BW) were estimated as BW = 2.14 × 10?4 × SL2.801 (R2 = 0.839; N = 413; P < 0.05) for females and BW = 1.31 × 10?4 × SL3.001 (R= 0.868; N = 272; P < 0.05) for males. The female to male sex ratio, 1.52 : 1, differed significantly from a 1 : 1 ratio. Females predominated in standard lengths >12 cm. Analyses of the monthly variation in the gonadosomatic index (GSI), the monthly proportions of macroscopic gonadal maturity, and the size distribution of oocytes consistently suggested a prolonged spawning season of H. sauvagei from March to August, with a peak from April to May. Logistic curves describing the relationship between proportion of maturity (Pr) at each length interval and standard length were estimated as Pr = 1/(1 + e26.867–0.306SL) (R= 0.999; N = 413; P < 0.05) for females and Pr = 1/(1 + e10.522–0.142SL) (R= 0.999; N = 272; P < 0.05) for males. Size at first maturity was estimated as 7.4 cm for males and 8.8 cm SL for females. Absolute fecundity varied from 563 to 5052, with a mean of 2413 ± 874 oocytes per ovary. The relative fecundity was estimated to be 41–299, with a mean of 171 ± 55 oocytes per ovary. The present study provides useful information for fishery management and resources conservation.  相似文献   

14.
ABSTRACT Little is known about the relationship between seasonal food availability and the foraging strategies of insectivorous Neotropical birds. We studied a population of Tropical Kingbirds (Tyrannus melancholicus), a primarily insectivorous species, in eastern Bolivia to examine relationships between rainfall, food availability, and foraging strategies throughout the year. Our study site in the southern Amazon Basin was characterized by strong seasonal variation in the abundance of the kingbird's main insect prey (coleopterans and hymenopterans), with reduced abundance during the nonbreeding season which largely overlaps the dry season. Overall, mean search times for insect prey by Tropical Kingbirds during the breeding (96.9 ± 85.6 [SD] sec) and nonbreeding (83.7 ± 91.2 sec) seasons did not differ (P= 0.23). However, during the nonbreeding season, kingbird search times were negatively, but nonsignificantly, correlated with coleopteran abundance (r2= 0.43, P= 0.16) and significantly and negatively correlated with hymenopteran abundance (r2= 0.72, P= 0.03). Although insect abundance differed seasonally, kingbird search times did not, perhaps because kingbirds forage on a greater variety of insects during the nonbreeding season or, during the breeding season, kingbird search times may be influenced by the need to monitor and defend nests as well as constraints on the types of prey that can be fed to nestlings. However, the reduced abundance of their primary insect prey and negative relationships between the abundance of those prey and search times during the dry, nonbreeding season suggest that Tropical Kingbirds in southern Amazonia may be food limited, potentially explaining why some migrate and spend that season elsewhere.  相似文献   

15.
We describe 18 microsatellite markers isolated in the cooperatively breeding chestnut‐crowned babbler (Pomatostomus ruficeps). The number of alleles ranged from seven to 16 per locus (mean Na = 10.4 ± 0.54 SE) and the expected heterozygosity ranged from 0.732 to 0.889 (mean HE = 0.836 ± 0.01 SE). Three of the 18 loci exhibited significant heterozygote deficiency, but the remaining 15 will be used to analyse population genetic structure and the mating system of this highly social species.  相似文献   

16.
Do the two parents at a nest make simultaneous decisions whether to care for their offspring or to desert? If a single parent is sufficient for rearing young, one parent (typically, the male) may desert and reproduce with a new mate within the same breeding season, leaving the other parent with the brunt of care. As each parent is expected to maximize its own reproductive success, the interests of the two parents do not necessarily coincide, and a sexual conflict over care may emerge. Here we investigate the process of clutch desertion in a small passerine bird, the Penduline Tit Remiz pendulinus. Among birds, this species has a remarkably variable breeding system, because a single parent (either the male or the female) may provide the full care of the young, whereas about 30% of clutches are abandoned by both parents. First, we show that biparental desertion occurs within a single day in 73.7% of the clutches (n = 14), whereas desertion decisions are sequential in 26.3% of the clutches (n = 5) (male first: 10.5% (n = 2); female first: 15.8% (n = 3); n = 19 clutches in total). Secondly, we observed the behaviour of both parents before desertion, and investigated whether desertion can be predicted from their behaviour. However, neither singing nor nest‐building behaviour predicted whether the male or the female would desert. We therefore suggest that biparental desertion may be simultaneous by male and female in our population of Penduline Tits. Furthermore, the parents do not appear to signal their intention to desert their mate. We argue that the parents’ interest may be actually to disguise their intention to desert.  相似文献   

17.
Background. Only a minority of those infected with Helicobacter pylori will develop gastric cancer. Stratification of H. pylori strains based on carcinogenic potential will provide a basis for selective surveillance and eradication therapy. We studied the anti‐H. pylori antibody profile in Asian patients with gastric adenocarcinoma to identify any H. pylori antigen that may be associated with an increased or decreased risk of gastric carcinoma. Patients and Methods. A case‐control study comparing the seroprevalence of antibodies with various H. pylori antigens in Singaporeans with gastric adenocarcinoma and the normal Singaporean population was carried out using both conventional immunoglobulin (Ig) G enzyme‐linked immunosorbent assay (ELISA) and Western blot immunoassay. Results. The seroprevalence among 44 gastric adenocarcinoma cases (70.5% males, mean age 66.7 ± 13.5 years) and 261 controls (49.8% males, mean age 61.5 ± 4.1 years) was 90.9% vs. 50.2% by IgG ELISA. In the H. pylori‐positive male population, those suffering from gastric adenocarcinoma had significantly lower seroreactivity to the 35‐kDa antigen compared with asymptomatic controls (p = .0198, OR = 3.79, 95% CI 1.24–11.61). Seropositivity to the 19.5 kDa antigen was also found to be associated with the presence of gastric adenocarcinoma in Singaporean males (p = .022, OR = 4.17, 95% CI 1.22–14.28). A ‘high‐risk’ phenotype consisting of absence of a band at 35‐kDa in combination with the presence of a band at 19.5‐kDa was significantly associated with the presence of gastric adenocarcinoma (p = .002, OR = 3.7, 95% CI 1.6–8.6). Conclusions. Stratification of H. pylori strains based on their potential for carcinogenesis, such as those strains that are seropositive for the 19.5 kDa antigen and seronegative for the 35‐kDa antigen, may provide a basis for selective eradication of H. pylori infection and future vaccine development.  相似文献   

18.
Adult survival, an important fitness component, is usually 1) lower in lighter individuals due to their reduced ability to survive winter conditions compared to heavier ones, especially in resident species at northern temperate latitudes and 2) lower in females compared with males due to higher reproductive costs incurred by females. In this paper, a capture–mark–recapture dataset of 649 cetti's warblers Cettia cetti ringed seasonally at two wetlands in central Portugal over an 11‐yr period (2000–2010) was modelled in a multi‐state framework to examine the influence of these individual covariates on apparent adult survival, while controlling for the presence of transient individuals in our study area. The probability of change in mass state (ψLight→Heavy, ψHeavy→Light) during the annual cycle was also estimated. Overall, birds survived better during spring–summer (breeding/moulting periods) compared with autumn–winter, but there was no effect of body mass on apparent adult survival probability. The modelling detected a significant interaction between sex and season, in which resident females survived better than resident males in spring–summer (?RF= 0.857 ± 0.117 and ?RM= 0.698 ± 0.181) while the opposite pattern was found in autumn–winter (?RM= 0.440 ± 0.086 and ?RF= 0.339 ± 0.084). In addition, cetti's warblers had a tendency to lose mass in spring–summer (ψHeavy → Light= 0.560 ± 0.063) and to regain mass in autumn–winter (ψLight→Heavy= 0.701 ± 0.069). This pattern of body mass change during the annual cycle may reflect energetic costs to reproduction and moulting, and/or a response to increased starvation risk during winter. High body mass, however, did not increase adult survival in this population presumably due to the relatively mild winter weather prevailing in central Portugal. Survival estimates are more likely to be explained by important ecological and behavioural differences between the two sexes in polygynous passerines. Our results highlight that studies aiming to identify the main factors shaping survival and individual fitness in polygynous species should be conducted during different phases of their annual cycle.  相似文献   

19.
BRIAN J. GILL 《Ibis》1982,124(2):123-147
I studied the breeding of Grey Warblers Gerygone igata (Muscicapidae: Acanthizinae) in forest near Kaikoura, New Zealand, between 1976 and 1979. Only males sang and singing occurred all year. From late July to January pairs defended self-contained territories of 0·25–1·73 ha but they occupied larger home ranges when not breeding. Territorial adults were strictly sedentary all year. The average annual mortality of breeding adults was 18·5% and the predicted life-expectancy 4·9 years, which is remarkable in a bird weighing 6–7 g. The breeding season from first building to last fledging was six months long and it began early. Exceptionally, Grey Warblers may build and lay before the shortest day. As the season progressed warblers nested lower on average, both in absolute terms and relative to the tree nested in and canopy at the site. Warblers built in 7–27 days then delayed up to eight days before laying. Only females built and at no stage of breeding did males feed their mates. Both sexes fed the young. Grey Warblers laid for 15–16 weeks of the year and first clutches were laid asynchronously during 5–6 weeks. Eggs of a clutch appeared at two-day intervals and each egg weighed 1·5 g when fresh (23% of mean adult weight). Clutch size was nearly constant (mean 3·9, mode 4, range 3–5). The incubation period was 17–21 days (mean 19·5 days) and the nestling period 15–19 days (mean 17·2 days). On average the clutch hatched over 1·4 days, even though incubation commenced with the laying of the last egg. Nestlings reached maximum weight on Days 13–14 on average and then receded in weight by 4%, apparently through loss of water. All healthy nestlings exceeded mean adult weight during development by up to 39%. Nestlings from broods of two were at first lighter on average than those from larger broods, but in the second half of the nestling period twins were significantly the heaviest. Grey Warblers were fed for 28–35 days after fledging and they survived well while dependent on parents. Fledglings dispersed up to 3 km or more at independence and only 5% per annum joined the breeding population. Of nests that received eggs, 42% produced at least one fledgling. On average each breeding adult raised 2·0 fledglings per season. Of 265 eggs in 73 nests 70% hatched and 38% produced fledglings. Of 185 nestlings 54% fledged. Probably the main cause of mortality of eggs and nestlings was predation by introduced rodents and mustelids. Grey Warblers raise two small broods slowly during a long breeding season, rather than investing in one large quickly-reared brood. In New Zealand's mild climate the warbler's food supply may not decline severely in winter, and the population of warblers may remain so close to the limit set by food that extra for breeding is hard to obtain. Thus the breeding strategy may be adapted to a restricted food supply.  相似文献   

20.
Abstract

The breeding of the bellbird (Anthornis melanura) was studied intensively over three seasons on Aorangi Island, Poor Knights Islands. Adult males defended territories all year but ventured beyond them to exploit localised food resources and to obtain water; some adults defended the same territory for at least 5 years. Adult females shared a territory with a male only during the breeding season. At other times of the year adult females were joined by juveniles and immatures and formed feeding flocks. The breeding season extended from late September to late December. A few nests were built on the ground but most were in dense vegetation, usually near the canopy. Peak egg-laying extended from mid-October to mid-November and only one clutch of two to four eggs was laid. Nest building and incubation were completed by the female alone but both parents fed nestlings. Fledglings stayed in the vicinity of the nest for several days, and were fed by both parents. Incubation and nestling periods were about 15 and 19 days respectively. Comparisons are made with the breeding biology of bellbirds and other native passerines on mainland New Zealand, and the importance of the predator-free enviomment of the Poor Knights Islands is stressed.  相似文献   

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