Seasonal organization of breeding and molting in the Fiscal Shrike (Lanius collaris)

Summary Free-living Fiscal Shrikes were investigated in Nakuru Kenya for seasonal patterns in breeding, gonadal size, molt and the plasma titers of LH, T in males and E 2 in females. Both breeding and molt were found to be seasonally restricted activities. A complete molt occurred from August to December after breeding had ceased. Although the gonads in some birds were well developed during the dry season, at the beginning of the year, no breeding was found until the onset of the heavy rains. It is proposed that severe drought inhibits reproductive activity and correspondingly the secretion of gonadal steroids (T and E 2) in Fiscal Shrikes without affecting increases in gonadal size.

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Brut- und Mauserzeiten beim Fiskalwürger (Lanius collaris)

Zusammenfassung Der Fiskalwürger ist die häufigste afrikanische Würgerart. Er ernährt sich von Insekten, Reptilien, kleinen Säugetieren und Vögeln. VonBrown &Britton (1980) undMacDonald (1980) wurde wegen dieser Beutevielfalt vermutet, daß er auch unter ungünstigen Umweltbedingungen (Trockenheit) brüten kann. In Nakuru, Kenya, wurde untersucht, ob jahreszeitlich bedingte Unterschiede in Brutaktivität, Gonadengröße, Mauser und in Plasmatitern von LH, T und E 2 vorhanden waren. Brutaktivität und Mauser waren mit der Hauptregenzeit korreliert. Die Brutzeit endete mit Beginn der Mauser, die von August bis Dezember dauerte. Obwohl die Gonaden bei einigen Vögeln schon während der Trockenzeit (Januar bis März) gut entwickelt waren, gab es bis zur Regenzeit keinen Hinweis auf Fortpflanzungsaktivität. Es wird angenommen, daß eine strenge Trockenzeit die Ausschüttung von Testosteron () und Estradiol () verhindert, ohne die Gonadengröße zu beeinflussen. In Gegensatz zu den vorher genannten Autoren wurde keine Fortpflanzungsaktivität in Trockenzeiten festgestellt. Das beruht vielleicht auf dem in einzelnen Jahren unterschiedlichen Ausmaß der Trockenzeit.

     

金钱豹和猪獾冠状动脉的解剖

为了阐明金钱豹(Panthera pardus)和猪獾(Arctonyx collaris)心冠状动脉的分支分布特征及血供情况,为心脏生物学及动物学研究提供结构基础资料,利用血管铸型和组织透明方法观察研究了金钱豹与猪獾心左、右冠状动脉的分支分布.结果表明,金钱豹和猪獾的心均由左右冠状动脉营养.金钱豹左冠状动脉分为室间隔支、前降支和旋支.前降支又分出左室上支、左室中支和左室下支.右冠状动脉沿途分出右室前支、右室后下支和右室后上支.猪獾左冠状动脉分为前降支和旋支.前降支又分出室间隔支和左室前支,旋支又分出左缘支和左室后支.其右冠状动脉沿途分出右室前支、右缘支和右室后支.金钱豹和猪獾心的室间隔均由发自左冠状动脉的独立的室间隔支营养,二者左右冠状动脉在膈壁的分布属于均衡型.     

Polygynandry, extra-group paternity and multiple-paternity litters in European badger (Meles meles) social groups

The costs and benefits of natal philopatry are central to the formation and maintenance of social groups. Badger groups, thought to form passively according to the resource dispersion hypothesis (RDH), are maintained through natal philopatry and delayed dispersal; however, there is minimal evidence for the functional benefits of such grouping. We assigned parentage to 630 badger cubs from a high-density population in Wytham Woods, Oxford, born between 1988 and 2005. Our methodological approach was different to previous studies; we used 22 microsatellite loci to assign parent pairs, which in combination with sibship inference provided a high parentage assignment rate. We assigned both parents to 331 cubs at > or = 95% confidence, revealing a polygynandrous mating system with up to five mothers and five fathers within a social group. We estimated that only 27% of adult males and 31% of adult females bred each year, suggesting a cost to group living for both sexes. Any strong motivation or selection to disperse, however, may be reduced because just under half of the paternities were gained by extra-group males, mainly from neighbouring groups, with males displaying a mixture of paternity strategies. We provide the strongest evidence to date for multiple-paternity litters, and for the first time show that within-group and extra-group males can sire cubs in the same litter. We investigate the factors that may play a role in determining the degree of delayed dispersal and conclude that the ecological constraints hypothesis, benefits of philopatry hypothesis, and life history hypothesis may all play a part, as proposed by the broad constraints hypothesis.     

Extrapair paternity, migration, and breeding synchrony in birds

To understand interspecific patterns in the strength of sexualselection, variation in the costs and benefits of exercisingmate choice needs to be evaluated. One manifestation of sexualselection in birds is the occurrence of greatly variable levelsof extrapair paternity (EPP). A proposed general explanationfor this variation is that the benefits to females in seekingextrapair copulations vary in a predictable manner accordingto the degree of breeding synchrony because females are betterable to assess potential extrapair partners when males are simultaneouslyin breeding condition. This hypothesis predicts a latitudinaltrend in EPP because birds tend to breed more synchronouslyaway from the equator. Expanding on previous geographicallyand taxonomically restricted tropical/temperate comparisons,we used phylogenetically independent standardized linear contraststo show that this positive relationship persists when all birdspecies for which EPP estimates currently exist are considered.However, if a third factor covaries with latitude in the sameway as breeding synchrony and EPP, this relationship need notbe causal. Migration could also account for latitudinal variationin the benefits to females of pursuing EPP, if migration isassociated with (1) hasty or (2) inaccurate mate choice, (3)facilitated assessment of male quality through the condition-dependenceof arrival time, or (4) increased genetic variance in male quality.We show that migration distance is positively related to theproportion of EPP and that migration can statistically explainthe latitudinal trend in EPP, even when confounding factorsare simultaneously controlled. Hence, alternative explanationsfor latitudinal variation in EPP may be feasible, and carefulintraspecific tests are needed to assess their relative importanceand their implications for geographical variation in life-historyevolution.     

Winter territoriality and fruit defence by the fieldfare ( Turdus pilaris )

During the winter seasons of 2000/2001 and 2003/2004, 27 territorial fieldfares Turdus pilaris were observed in two study areas in southern Poland. Of these, 22 were in gardens or orchards with apple trees. Only 0.5% of all fieldfares noted during field surveys were territorial, and only 1.7% of the checked gardens and orchards were inhabited by that species. Fieldfares defended fruit against several species, including conspecifics. The probability of the presence of territorial fieldfares within a habitat patch was higher in patches with a higher density of apples, but was not related to the size or degree of isolation of the patch. The duration of holding territory was positively correlated with apple density and negatively correlated with the presence of intruders (mainly flocks of non-territorial fieldfares). The results suggest that food density and the presence of intruders are key factors affecting the presence of territorial thrushes during winter.     

Group living, breeding behaviour and territoriality in the Subdesert Mesite Monias benschi

In 1997–2000 we studied a population of Subdesert Mesites Monias benschi consisting of 35–68 adults comprising 32 groups of two to nine birds (modal group size of four). The study population was significantly male-biased in 1999 but not in 1997 or 1998. Overall, both sexes were philopatric, but when dispersal (or eviction) occurred, it appeared to be female-biased. Over 40% of groups contained more than two adult males, whilst < 15% contained more than two adult females. Whilst there was no evidence of behavioural dominance by females, intrasexual aggression within groups was observed only amongst females. In contrast to other birds occupying the same habitat, breeding in mesites was not tied to rainfall, and occurred throughout the year. Each breeding unit constructed several nests every year, only one of which was used. All adult males and at least one adult female co-operated to raise one or two clutches of one or two eggs per year. Males and females contributed equally to incubation. Chick production and chick survival were not related to group size or territory size. Groups defended large, permanent, and multipurpose territories and all group members contributed to territory defence. Territory size was positively correlated with the number of males in groups, but not with overall group size. Territories were tightly packed with very few areas unoccupied. Transect surveys conducted throughout the narrow geographical range of this species revealed its presence in a range of semi-arid habitat types. Small groups were more likely to be detected in intact, high-stature forest, whilst large groups were more likely to be detected in low-stature forest containing numerous spiny, xerophytic trees Didierea madagascariensis .     

Effects of supplementary feeding on territoriality, breeding success and survival of pheasants

1. The effects of supplementary food in spring on subsequent pheasant breeding in an intensively farmed area in southern England were assessed by a large-scale, replicated field experiment.
2. Territorial cock pheasants were counted in April, and the breeding success and survival of radio-tagged hens were monitored in six 1-km² plots during 1994 and 1995. Total numbers of young reared and post-breeding pheasant densities were found by August counts. In 1994, three randomly selected plots were supplied with wheat grains via hoppers along woodland edges and hedgerows. The other three plots acted as controls and the treatments were reversed in 1995.
3. The density of cock territories increased significantly in food-supplemented plots (44 ± 8 km−2) in relation to control plots (29 ± 8 km−2), and the presence of hoppers significantly affected the locations of territories. However, similar proportions of territorial males acquired harems in the control and food-supplemented plots. Hen density did not increase and, consequently, the mean harem size was significantly lower with supplementary feeding.
4. Hens given supplementary food did not nest earlier and the number of nests initiated, clutch sizes and the proportion of successful nests did not differ significantly from those of controls. However, hens supplied with supplementary food re-nested significantly more quickly following the loss of a nest or brood.
5. Radio-tagged hens did not rear significantly more young with supplementary feeding. Hen survival was unchanged and post-breeding pheasant densities were no higher.
6. On present evidence, spring feeding cannot be advocated as a management technique to improve the breeding success of pheasants surviving the winter.     

Multiple paternity and breeding system in the gopher tortoise, Gopherus polyphemus

Little is known about the reproductive behaviors and the actual outcomes of mating attempts in the gopher tortoise (Gopherus polyphemus). We examined the mating system and reproductive behaviors of a population of gopher tortoises in central Florida. Using microsatellite markers, we assigned fathers to the offspring of seven clutches and determined that multiple fathers were present in two of the seven clutches examined. We found that gopher tortoises exhibited a promiscuous mating system with larger males fertilizing the majority of clutches. The advantage of larger males over smaller males in fertilizing females may be a result of larger males winning access to females in aggressive bouts with other males or larger males may be more attractive to females. Clutches produced by larger females tended to be sired by a single male, whereas clutches of smaller females tended to be sired by multiple males.     

Extrapair paternity is influenced by breeding synchrony and density in the common yellowthroat

The effects of breeding synchrony and density on levels of extrapair paternity in birds are controversial. We used multilocus DNAfingerprinting and microsatellite analysis to examine the effectsof breeding synchrony and density on levels of extrapair paternityin the common yellowthroat (Geothlypis trichas). As in manyNeotropical migrants, breeding synchrony was greatest at thebeginning of the breeding season. Levels of extrapair paternitywere higher after the peak in synchrony, leading to an overallnegative relationship between extrapair paternity and breeding synchrony. However, there was a significant interaction betweenbreeding synchrony and density, as levels of extrapair paternitywere higher only for males breeding when both synchrony anddensity were low. We discuss several possible explanationsfor this interaction, including lower quality males or territoriesin low density areas and greater demands on mate guarding among males with larger territories. Most studies have not consideredsimultaneously the effects of breeding synchrony and densityon extrapair paternity. Our results suggest that ecologicalcorrelates of paternity may be revealed only after testingfor interactions in multivariate analyses.     

Home range and territoriality of Australian owlet-nightjars Aegotheles cristatus in diverse habitats

Sedentary Australian owlet-nightjars Aegotheles cristatus roost in cavities year-round, and are thought to mate for life and maintain stable home ranges throughout the year. These factors lead to the prediction that they should be highly territorial, yet nothing is known about their home range requirements or level of site fidelity. I used radio-telemetry coupled with GPS recordings to determine home range size in the semi-arid zone of central Australia (13 birds over two winters) and in a eucalypt woodland in the Northern Tablelands of NSW (14 birds over one calendar year). The mean home range in the eucalypt woodland was 17.7 ha based on the minimum convex polygon (MCP) method and 17.4 ha based on the fixed kernel contour (95%), whereas it was 23.8 ha and 24.1 ha based on the MCP and kernel methods in the desert respectively. With the exception of mated pairs (range overlap 41.9%), there was little overlap among individuals in home range areas (<13.0%), even in the densely populated woodland. Home range size did not differ significantly between seasons or study sites; nor was it correlated with arthropod abundance. Owlet-nightjars exhibited high site fidelity, using the same home range throughout the year with a 68% overlap between seasons. These data, plus anecdotal records of aggression and vocalizations, suggest that this species is highly territorial, yet individuals live in close proximity to conspecifics. The degree of territoriality may be due to the obligate cavity roosting behaviour of owlet-nightjars and the need to defend areas with known roost hollows.     

Male rank, female breeding synchrony, and patterns of paternity in the boat-tailed grackle

Species in which males directly defend groups of breeding femalesoften have extreme skew in observed male mating success. Inonly a few species, however, has a corresponding skew in fertilizationsuccess been confirmed. Furthermore, the ecological and socialfactors contributing to variation in fertilization success needinvestigation. This study examined competition for mates andpaternity in the boat-tailed grackle (Quiscalus major). Observationsat colonies of nesting females revealed that the toprankingor alpha males performed more than 70% of the copulations. DNAfingerprinting indicated that alpha males sired less than 40%of nestlings. Nevertheless, analysis of band-sharing scoresamong nestlings from different nests suggested that alpha malessired more than three times as many offspring as any other individualmale. Because few nestlings were sired by the nonalpha malesthat associated with colonies, females must have mated withother males while on trips away from colonies. Analysis of paternitywithin broods revealed that at least half of all females hadtheir brood fertilized by more than one male. Alpha males' successat fertilizing eggs did not vary with the number of simultaneouslyreceptive females within a colony. Our results suggest that maleand female behavior in female-defense polygyny results fromcomplex coevolution of the sexes.     

Effects of breeding density, synchrony, and experience on extrapair paternity in tree swallows

Breeding density, synchrony, and experience are expected toinfluence the frequency of extrapair paternity in birds. UsingDNA fingerprinting, we examined the effect of these factorson tree swallows nesting at relatively high (grids of nest-boxes)and low (solitary boxes at least 100 m from the nearest neighbor)densities and in relatively synchronous (Alberta) and asynchronous(Ontario) populations in Canada. The mean percentage of extrapairoffspring per nest did not differ significantly between birdsnesting in grids (43%, n = 22 families) and solitary boxes (57%,n = 12 families). Similarly, there was no significant differencein the mean percentage of extrapair offspring per nest betweenrelatively synchronous (60%, n = 12 Alberta families) and asynchronous(41%, n = 22 Ontario families) populations. We also found noconsistent pattern between extrapair paternity and breedingexperience among seven males and seven females examined overtwo to three breeding seasons. Female tree swallows can influencethe fertilization success of extrapair males by active selectionand rejection of copulation partners. We suggest that this abilitylimits the predicted effect of various ecological factors onthe frequency of extrapair paternity     

Effects of age,territoriality and breeding on survival of Bonelli’s Eagle Aquila fasciata

Survival typically contributes most to population trends in long‐lived birds and its accurate estimation is therefore vital for population management and conservation. We evaluated the effects of age, territoriality and reproduction on survival in Bonelli’s Eagle Aquila fasciata through multistate capture‐mark‐recapture analyses on a long‐term dataset. Monitoring was carried out in southeast France (1990–2008) and involved the surveying of territorial Eagles, the marking of fledged chicks, and the recording of resightings and recoveries of marked non‐territorial and territorial birds. Survival improved with age, but territoriality was not retained in the best model; yearly survival was estimated at 0.479 for fledglings (to 1 year of age), 0.570 for 1‐ and 2‐year‐olds, and 0.870 for 3‐year‐old and older individuals. The second best model supported a further increase in survival from 3‐year‐olds (0.821) to older individuals (0.880). In the third best supported model, territoriality enhanced survival, but only in 2‐year‐olds (0.632 vs. 0.562 for non‐territorial). We found no correlation between the previous breeding stage and future survival, consistent with the long lifespan of the study species. Nevertheless, 4‐year‐old and older successful breeders were more likely to breed the following year than failed adult breeders (0.869 vs. 0.582), suggesting that the cost of reproduction is small in comparison with the variation in quality among individuals or their territories.     

猫儿山小鲵(Hynobius maoershanensis)繁殖期生境选择

在广西猫儿山自然保护区的山顶湖、三江源、野人湖等地区,基于植被类型、水体类型、岸边条件、卵袋悬挂物、水中覆盖物、人为干扰程度等20种生境因子,通过61个样方（26个选择样方和35个对照样方）,对猫儿山小鲵繁殖期的生境选择做进行了研究,并得出以下4个主要结论：（1）在基于描述型生态因子的研究中,结果显示选择样方与对照样方在水体类型、岸边条件、水中覆盖物3种因子上差异显著,而植被类型、卵袋悬挂物、人为干扰程度3种生态因子对其生境选择无显著影响。（2）基于14种数值型生态因子的研究结果显示,选择样方和对照样方间的植被盖度、水体面积、水体流速和水底泥沙比方面具有显著差异。植被盖度较低、水体面积较大的水域、水体流速低和水底泥沙比较低的水域是猫儿山小鲵的优选繁殖地。（3）基于14种数值型生态因子的逐步判别表明,通过植被盖度和水底泥沙比2个生态因子可分辨选择样方和对照样方,正确判别率达80.3%,且对于检验也具有最大的贡献值,分别为0.840和0.622。（4）对猫儿山小鲵卵袋对数和14种数值型生态因子的逐步回归分析结果显示猫儿山小鲵在繁殖期生境选择与地表湿度显著正相关,与植被盖度呈显著负相关,高地表湿度和低植被盖度对猫儿山小鲵的产卵量起促进作用。猫儿山小鲵繁殖期间偏好的微生境为较低植被盖度、较大面积水体和较低流速、低水底泥沙、多水中覆盖物、复杂岸边条件的静水型水塘,与选择偏好的微生境相关的生态因子是猫儿山小鲵繁殖期生境选择的主要因子。     

Adult male collared lizards, Crotaphytus collaris, increase aggression towards displaced neighbours

Differential responses to neighbours and strangers (the dear enemy phenomenon) and individual recognition presumably evolve to reduce costs of territorial defence. Territorial residents have been found to demonstrate reduced aggression towards neighbours wherever they are encountered along that resident's territory boundary except for when the neighbour is displaced to the boundary opposite the shared boundary. In this new location, the displaced neighbour represents a greater threat to the resident's territory ownership, and should be treated as equally aggressive as a stranger. Finding increased aggression towards displaced neighbours has been interpreted as individual recognition, but these results do not provide sufficient evidence to rule out the possibility that the resident sees the neighbour out of its normal context as just another stranger. We tested the hypothesis that territorial collard lizards can individually recognize neighbours and will increase aggression towards them as the threat to territorial ownership increases. Resident males treated neighbours that had been moved to the opposite boundary as equally aggressive as strangers. However, residents responded more aggressively towards strangers than towards neighbours on natural territories (the dear enemy phenomenon) and also in neutral arena encounters. Our results suggest that resident male collared lizards are able to recognize individuals regardless of context and respond to them according to the threat that they pose. Copyright 2003 The Association for the Study of Animal Behaviour. Published by Elsevier Science Ltd. All rights reserved.      

Intraspecific variation ofDrosophila buzzatii larval breeding success onOpuntia: A yeast-plant-insect relationship

The cactophilic species,Drosophila buzzatii, normally breeds in decaying pockets ofOpuntia cladodes, in which there is a complex interaction with the microbial flora, especially yeast species. Isofemale lines were used to estimate genetic variation among larvae reared on their natural feeding substrate. Four naturally occurring cactophilic yeast species isolated from the same Tunisian oasis as theDrosophila population were used. Two fitness components were studied for each line, viability and developmental time. Genetic variations amongD. buzzatii lines were observed for both traits. A significant yeast species x isofemale line interaction for viability was also evidenced, suggesting the occurrence of specialized genotypes for the utilization of breeding substrates. This genetic heterogeneity in the natural population may favor a better adaptation to the patchily distribution of yeasts.