Does prey availability affect the foraging effort and breeding success in the Antarctic Shag (Phalacrocorax bransfieldensis)?

Information on diet composition, foraging effort and breeding success of the Antarctic Shag (Phalacrocorax bransfieldensis) was obtained at three colonies on the Antarctic Peninsula, dur-ing the 1997/98 breeding season. Fish was the most important prey at each of the colonies sampled, followed by octopods and gastropods. Among colonies, there were marked differences in the size of the fish consumed, which was smaller at Py Point. This was mainly due to the larger number of speci-mens of the smallest fish prey species consumed there. Shags from Py Point performed longer forag-ing trips and spent more time per day foraging. Although at the beginning of the study the number of chicks per nest observed at the three colonies was similar, the number surviving to fledge at Py Point was markedly lower. The relative higher foraging effort and lower breeding success observed at Py Point might be related to the differences in the fish consumed between colonies. My results suggest that the decline in the inshore fish populations observed around the South Shetland Islands could be one of the reasons explaining the steady decrease in the number of breeding Antarctic Shags observed at colonies monitored in this archipelago.

Long-term trends in the abundance and breeding performance in Adélie penguins:the Argentine Ecosystem Monitoring Program

In this work,we report long-term trends in the abundance and breeding performance of Adélie penguins(Pygoscelis adeliae)nesting in three Antarctic colonies(i.e.,at Martin Point,South Orkneys Islands;Stranger Point/Cabo Funes,South Shetland Islands;and Esperanza/Hope Bay in the Antarctic Peninsula)from 1995/96 to 2022/23.Using yearly count data of breeding groups selected,we observed a decline in the number of breeding pairs and chicks in crèche at all colonies studied.However,the magnitude of change was higher at Stranger Point than that in the remaining colonies.Moreover,the index of breeding success,which was calculated as the ratio of chicks in crèche to breeding pairs,exhibited no apparent trend throughout the study period.However,it displayed greater variability at Martin Point compared to the other two colonies under investigation.Although the number of chicks in crèche of Adélie penguins showed a declining pattern,the average breeding performance was similar to that reported in gentoo penguin colonies,specifically,those undergoing a population increase(even in sympatric colonies facing similar local conditions).Consequently,it is plausible to assume a reduction of the over-winter survival as a likely cause of the declining trend observed,at least in the Stranger Point and Esperanza colonies.However,we cannot rule out local effects during the breeding season affecting the Adélie population of Martin Point.

Nest-site Choice and Breeding Success among Four Sympatric Species of Passerine Birds in a Reedbed-dominated Wetland

The efficacy of nest-site choice ultimately determines the breeding success of birds. Comparisons of the reproductive strategies of various bird species which inhabit the same habitat may provide insights on the evolution of the diverse life-history strategies in birds. In this study, nest-site choice and breeding success of four species of passerine birds that rely on reeds for reproduction were investigated in a wetland in Hebei, China. The four species were the Oriental reed warbler(Acrocephalus orientalis)(ORW), the blunt-winged warbler(Acrocephalus concinens)(BW), the reed parrotbill(Paradoxornis heudei)(RP), and the vinous-throated parrotbill(Sinosuthora webbiana)(VP). Our results showed that breeding nests of the four species were distributed in a mosaic pattern within the same habitat, with similar nest shapes/structures and nest-sites in the reeds. The only characteristics which differed significantly among the species were nest height above the water surface, height of reeds where nests were placed, and density of reeds around the nest site. In addition, the starting time of reproduction clearly differed for the four species. The breeding success rates of the four species were 34.5%(86/249) for ORW, 35.3%(6/17) for BW, 38.5%(15/39) for RP, and 40.9%(9/22) for VP in the two study years. The main factors affecting the breeding success were nest predation and poor weather conditions, like heavy rainstorms and wind, while nest parasitism by the common cuckoo(Cuculus canorus) represented an important factor for breeding failure only in the Oriental reed warbler. Our study demonstrated that these four sympatric species of passerine birds inhabiting the same wetland exhibit differences in terms of nest-site choice and breeding phenology.

Integrative demographic study of the Iberian painted frog(Discoglossus galganoi):inter-annual variation in the effective to census population size ratio,with insights on mating system and breeding success

In the face of worldwide amphibian declines,integrative studies combining individual-based information and genetic data represent a powerful approach to produce robust,reliable,and comparable assessments of demographic dynamics.The Iberian painted frog(Discoglossus galganoi)is endemic to Spain and Portugal and shows decreasing population trends across its range,but few studies have attempted to estimate census sizes or assess genetic diversity in wild populations,and little is known about their reproductive biology.We applied an integrative approach based on the combination of capture-mark-recapture data and multilocus genotypes to monitor a breeding population of D.galganoi in central Spain during two consecutive breeding seasons,focusing on the estimation of demographic parameters and their temporal variation.Specifically,we estimated the number of adults(Na),the effective population size(Ne),and the effective number of breeders(Nb),as well as survival and migration rates.We documented a>50%decrease in the estimated number of adults of both sexes between the breeding seasons of 2018 and 2019,probably associated with reduced rainfall in the latter.Estimates of Nb and the Nb/Na ratio were low in both seasons,with a 20–30%decrease in Nb and a 47%increase in the Nb/Na ratio in 2019.Based on the reconstruction of pedigrees from larval and adult genotypes,we provide the first genetic evidence of polygamy in males and females of D.galganoi and the first estimates of breeding success in the species.

Habitat-dependent breeding biology of the Blue Tit(Cyanistes caeruleus)across a continuous and heterogeneous Mediterranean woodland

Mediterranean woodland environments are characterised by high spatial and temporal heterogeneity,which means the inhabiting species face a wide variety of selective pressures.Species may respond differently to habitat heterogeneity and so distinct eco-evolutionary scenarios may be responsible for the inter-habitat variability in reproductive strategies observed in certain species.The inter-forest variability of some reproductive traits in passerines has been examined by comparing forest patches or separated fragments.However,there is still little information regarding how such highly mobile animals adjust their breeding performance across continuous and heterogeneous woodlands.Here we studied the reproductive performance of a population of Blue Tits(Cyanistes caeruleus) in an area of continuous Mediterranean woodland that included two mountain slopes and four different types of forest,ranging from deciduous oak forests to perennial non-oak forests.We studied the habitat heterogeneity and inter-forest phenotypic variation in terms of reproductive performance and adult and nestling biometry,besides also exploring the effects of ectoparasites on Blue Tit reproduction.Eggs were laid earliest in deciduous Pyrenean Oak(Quercus pyrenaica) forests,while clutch size and the number of fledglings were highest in the humid Pyrenean Oak forest,which had the greatest tree coverage and most humid climate,and lowest in the coniferous Scots Pine(Pinus sylvestris) forest.There were no inter-forest differences in hatching(percentage of nests with at least one egg hatched) and fledging(percentage of nests in which at least one nestling fledged)success.Similarly,there were no inter-forest differences in adult and nestling biometry,but adults that raised more fledglings had a lower body mass,while males whose females laid larger clutches had smaller tarsi.Most ectoparasites did not affect Blue Tit reproduction,although Culicoides had a negative impact on nestling body mass.These results suggest that Blue Tits can adjust their reproductive effort to the forest where they breed even across a very small spatial scale.Different eco-evolutionary scenarios,such as phenotypic plasticity or genetic structuring and local adaptation,might explain the phenotypic differentiation in the reproductive strategies observed over small areas in woodlands.

Distribution and reproductive behavior of penguins on Ardley Island and their environmental impact factors

During the 2006/07 Antarctic summer,the species population,distribution and reproductive behavior of penguins in areas near the Great Wall Station were investigated.Five species of penguin were recorded：gentoo penguin（Pygoscelis papua）,adelie penguin（P.adeliae）,chinstrap penguin（P.antarctica）, King penguin（Aptenodytes patagonicus） and Emperor penguin（A.forsteri）. The first three species bred locally,while the other two species were observed occasionally.Ardley Island is one of the most important breeding areas for penguins.After the breeding season of 2006/07,there were a total of about 17 234 penguins and the breeding success rate was 0.40—1.41.Comparing with historical data,changes in penguin species populations and distribution were analyzed, and their relationships with the environment,climate change and human activity were investigated.

San Diego Zoo:Success in Breeding

Giant pandas have become very popular in U.S.zoos. One in particular, the San Diego Zoo, has been extremely successful at making the pandas feel at home and getting them to breed. In 1999, it became home tothe first surviving panda cub born in the United States.

Male-like testosterone levels inhibit oviposition in a female parrot： A breeding experiment in budgerigars

Studies in several songbird species have shown that treating females with the androgenic steroid hormone testoste- rone （T） can negatively affect female reproductive behaviors and breeding success. As the effects of T on females appear to be species-specific, it is not clear if similar effects of high T occur in non-songbird species. Here, we studied the effects of T supplementation on female reproductive behavior and oviposition in the budgerigar, Melopsittacus undulatus, a small monogamous parrot species with distinct sex differences in parental behavior. We experimentally increased T concentrations to male-like levels in T-treated females compared to controls and we allowed females to breed. We found no significant effects of treatment on the latency to enter the nestbox but T treatment significantly interfered with oviposition. Our results show that T-treated females were seven times less likely to produce a clutch than control females. As we found that T treatment had a strong inhibitory effect on oviposition, our results indicate that female budgerigars suffer fitness costs from male-like plasma T levels. Therefore, it may be possible that, also in non-songbird species, selection for higher T levels in males is constrained by a correlated response to selection which imposes fitness costs on females in terms of reproduction. Evaluating whether or not this is indeed the case requires further work combining different approaches to the study of the evolution of male and female testosterone levels [Current Zoology 61 （4）： 586-595, 2015].

Oral disease is linked to low nestling condition and brood size in a raptor species living in a highly modified environment

Anthropogenic stressors can favor the occurrence of noninfectious disease that can be worsened by the impact of opportunistic pathogens,making the epizootiology of environmental diseases difficult to unravel.The incidence and impact of oral lesions in nestlings of a facultative scavenger species,the black kite Milvus migrans,were examined over seven breeding seasons in the highly degraded environment close to Madrid,Spain.We found an overall prevalence of 31%of nestlings with oral lesions,with no clear spatial pattern in nests with affected and unaffected individuals.The occurrence and number of oral lesions were negatively associated with nestling body condition and brood size.Broods,where all siblings had oral lesions,were smaller than those where some or all siblings were apparently healthy,suggesting that oral disease could be causing nestling mortality and,consequently,brood size reduction.In turn,nestling body condition was negatively affected by lesion occurrence,brood size,and laying date.Although these relationships were bidirectional,piecewise structural equation modeling analyses showed a greater negative effect of body condition on lesion occurrence than vice versa,indicating that nestlings in poorer body condition were more likely to develop oral lesions(which could contribute to aggravate their state of deterioration)than those in better condition.Nestlings from small broods were also more likely to have oral disease(directly or indirectly through their lower body condition)than nestlings from large broods.Nestlings that hatched last in the broods showed greater development stress than those that hatched first.Anthropogenic stressors could trigger poor body condition,and contribute to microbiota dysbiosis-related diseases.Although further research is needed to determine the consequences for the long-term fitness of individuals,actions should be taken to mitigate adverse conditions that may favor the appearance of environmental diseases associatedwithperi-urbanareas,giventheirrapidexpansion overnatural areas.