The clutch size,incubation behavior of Reeves’s Pheasant(Syrmaticus reevesii) and their responses to ambient temperature and precipitation

Weather conditions play a pivotal role in embryo development and parental incubation costs,potentially impacting the clutch size and incubation behavior of birds.Understanding these effects is crucial for bird conservation.Reeves’ s Pheasant(Syrmaticus reevesii) is a threatened species endemic to China,which is characterized by female-only incubation.However,there is a lack of information regarding the impact of weather conditions on clutch size and incubation behavior in this species.Using satellite tracking,we tracked 27 wild female Reeves’ s Pheasants from 2020 to 2023 in Hubei Province,China.We explored their clutch size and incubation behavior,as well as their responses to ambient temperature and precipitation.Clutch size averaged 7.75 ±1.36,had an association with average ambient temperature and average daily precipitation during the egglaying period,and was potentially linked to female breeding attempts.Throughout the incubation period,females took an average of 0.73 ±0.46 recesses every 24 h,with an average recess duration of 100.80 ±73.37 min and an average nest attendance of 92.98 ±5.27%.They showed a unimodal recess pattern in which nest departures peaked primarily between 13:00 and 16:00.Furthermore,females rarely left nests when daily precipitation was high.Recess duration and nest attendance were influenced by the interaction between daily mean ambient temperature and daily precipitation,as well as day of incubation.Additionally,there was a positive correlation between clutch size and recess duration.These results contribute valuable insights into the lifehistory features of this endangered species.

Large-brained birds lay smaller but heavier clutches

The brain is among the most energetically costly organs in vertebrates,and thus trade-offs have been hypothesized to exert constraints on brain size evolution.The energy trade-off hypothesis(ETH) predicts that reducing the energy consumption of reproduction or other costly tissues should compensate for the cost of a large brain.Egg production in birds requires a large proportion of the total energy budget,and a clutch mass in some bird species can outweigh the body mass of the female.To date,this hypothesis has mainly been tested in mammals and ectothermic animals such as anurans and fishes.We collated data on adult brain size,body mass and eggproduction traits such as clutch size,egg mass and annual broods from published studies,and conducted a phylogenetic comparative test of the interplay between egg-production investment and brain size evolution across bird species.After controlling for phylogenetic relationships and body size,we find a negative correlation between brain size and clutch size across 1395 species,which favored ETH.However,when egg mass was integrated in models,positive associations were detected between brain size and mass of eggs(via egg mass,clutch mass and annual total egg mass).Our results suggest that brain size trades off against egg-production only via certain aspects(e.g.,clutch size).By contrast,a positive relationship between brain size and total egg reproduction(e.g.,clutch mass and annual total egg mass) implied increased total energy budget outweighing energy allocation across bird species.Our study shows that there is no general energy trade-off between brain size and eggreproduction investment,and suggests that brain size evolution follows mixed strategies across bird species.

Geographic Variation in Clutch and Egg Size for the Lizard Phrynocephalus przewalskii(Squamata:Agamidae)

In order to tease apart proximate vs. ultimate sources of variation in reproductive strategy, studies have increasingly focused on populations rather than species as the unit of interest. The reproductive parameters of Phrynocephalus przewalskii （Agamidae） in different populations within the same phylogenetic clade were compared in this study. Female SVL, clutch size, egg volume and clutch volume varied significantly among populations. With increase in latitude, clutch size increased, while egg size decreased. Relatively fewer but larger eggs were produced with increasing of population density. Food availability had positive effects on clutch size, but no effect on egg size. Our result indicated that latitude, food availability and population density may be the proximate factors affecting the reproductive parameters ofP. przewalskii.

Variation in egg and clutch size of the Black Redstart(Phoenicurus ochruros) at the northeastern edge of the Qinghai-Tibetan Plateau

Background: In birds, the trade-off between the quality and number of nestlings is one of the most important theories of the evolution of life history of birds, which is closely related with climate. We investigated variation in egg and clutch size of the Black Redstart(Phoenicurus ochruros) on the northeastern edge of the Qinghai-Tibetan Plateau in order to explore and test the relation between egg size and clutch size and the rules governing the variation in these two components with climate change.Methods: We monitored each located nest daily to determine the exact laying order of the eggs and measured their sizes. The variations in egg volume and clutch size between 2008 and 2009 were studied by independent sample t tests. The difference in egg volume in the sequence of the laying order was tested by Kendall's W test and we employed Pearson correlations to investigate the relation between egg size and laying order. All statistical analyses were performed with IBM SPSS Statistics, version 19.0Results: In 2008, the mean egg volume of the Black Redstart was 2.40 and clutch size wer± 0.20 cm^3(n e 2.26 = 50), and the mean clutch size 4.90 ± 0.57(n = 11). In 2009, the mean egg volumeation between eg± 0.18 cm^3(n g size and layin= 74) and 5.20 g order(r ± 0.26(n = 15) respectively. We found a significantly positive correl, while egg size was strongly and negatively correlated with clutch size(r = 0.397, p = 0.030) smaller eggs but a larger clutch in a brood in a resource-rich year, w= h-0.274, p ereas large= 0.002). Black Redstarts tend to layr eggs but smaller clutches are produced in a harsh year.Conclusions: The Black Redstart adopted a "brood survival strategy" to ensure that more offspring could survive. The Black Redstart' trade-off in egg volume and clutch size would guarantee that it will gain maximum benefit in any case.

Timing of breeding as a determinant of nest success of the vulnerable Chestnut Seedeater(Sporophila cinnamomea)in grasslands of southern South America

The breeding traits of Sporophila seedeaters have been relatively well studied in recent years;nevertheless,a group of ten species in the genus,known as southern capuchinos,remain understudied.That is the case with Chestnut Seedeater(Sporophila cinnamomea),a species vulnerable to extinction,which breeds in the grasslands of southeast South America and,after reproduction,migrates towards the Cerrado region in central Brazil.Here,we investigated breeding ecology and calculated average clutch size,productivity,the sex ratio of nestlings,and estimated nest success.Then we tested(1)whether there is a relationship between the number of active nests and environmental variables,(2)whether the nestling sex ratio deviates from the 1:1 ratio,(3)whether clutch size varies between breeding seasons,and(4)whether the nest success is related to starting date,nest age,plant support,nest height from the ground,and clutch size.During two breeding seasons(October-March 2018-2020),we monitored 98 nests.We generated survival models with five interacting covariates to assess the survival of the nests.We recorded the entire breeding period for Chestnut Seedeater,which was estimated to be 4.6 months,similar to other migratory seedeaters.Clutch size did not differ between breeding seasons.The sex ratio of nestlings was not significantly different from the 1:1 ratio.Nest success was 31%,and predation was the leading cause of unsuccessful nests(83%).The daily survival rate was 0.95±0.01.The main predictor of nest survival was the covariate starting date.These findings,added to other aspects of the species’natural history described here,may help illuminate the ecology and behavior of Chestnut Seedeater and other southern endangered capuchinos,and grassland-dependent species of South America.

Age Structure of Females in a Breeding Population of Echinotriton chinhaiensis(Caudata:Salamandridae) and Its Conservation Implication

Knowledge of life history is important for understanding possible connections to population declines. Here, we investigated the female age structure and fecundity of Echinotriton chinhaiensis, one of the most endangered salamanders in the world, using skeletochronology based on specimens collected in 2008 and 2009 from a population in Ruiyansi, northeast of Ningbo, Zhejiang, China. The results showed that most female salamanders were between 5 and 6 years of age, with the minimal reproductive age, predicted to be 3 years, and the clutch size correlated to the body size. We argue that both delayed attainment of sexual maturity and low fecundity make this species more vulnerable to extinction.

Nest-site selection and breeding ecology of Streaked Wren-Babbler(Napothera brevicaudata)in a tropical limestone forest of southern China

Background: The breeding information of most birds in Asian tropical areas,especially in limestone forests,is still poorly known.The Streaked Wren-Babbler(Napothera brevicaudata) is an uncommon tropical limestone bird with a small range.We studied its nest-site selection and breeding ecology,in order to understand the adaptations of birds to the conditions of tropical limestone forest in southern China.Methods: We used methods of systematical searching and parent-following to locate the nests of the Streaked Wren-Babbler.We measured characteristics of nest sites and rock cavities.Data loggers and video cameras were used to monitor the breeding behavior.Results: All the observed nests of the Streaked Wren-Babbler were placed in natural shallow cavities or deep holes in large boulders or limestone cliffs.The great majority(96.6%) of Streaked Wren-Babbler nests had three eggs with an average fresh weight of 3.46-± 0.43 g(n = 36,range 2.52-4.20 g).Most(80.4%) females laid their first eggs between March and April(n = 46).The average incubation and nestling period of the Streaked Wren-Babbler was 10.2 range 9-11 days),respectively.Most(87.9%) nests h± 0.4 days(n = 5,range 1011 days) and 10.5 ± 0.8 days(n = 6,ad at least one nestling fledge between 2011 and 2013(n = 33).Conclusions: Our study suggests that several features of the breeding ecology of the Streaked Wren-Babbler,including building nests in rocky cavities,commencing breeding earlier than most species,and reducing foraging times during the incubation period,are well-adapted to the unique habitat of tropical limestone forest.

Female Reproductive Cycles of Phrynocephalus przewalskii (Lacertilia:Agamidae) in the Tengger Desert,China

The timing of reproduction can significantly affect an offspring＇s fitness, thereby also influencing the fitness of the parents, especially in species inhabiting extreme environments, such as deserts. Female reproductive cycles in Phrynocephalus przewalskii were studied from April to September 2008. Significant cycles of gonadal volume were found in all studied populations and the cycles were similar among the various populations. Females began vitellogenesis in April and contained oviductal eggs form May to June. Gonad volume decreased significantly in July and reached minimum volume from August to September. The follicular growth was negatively correlated with increasing precipitation and temperature in all populations. Hatching occurs during summer and early fall, when most of the annual rainfall occurs. Mean clutch size based on all populations was 2.7 ± 0.9 SE （n = 71）.

Elevational Variation in Reproductive Strategy of a Widespread Lizard:High-Elevation Females Lay Fewer but Larger Eggs

Identifying how reproductive strategies such as the trade-off between clutch size versus egg mass vary with elevational gradients is essential for our understanding of life-history evolution.We studied lacertid lizards(Eremias argus)in China,from six populations at different altitudes,to assess elevational variation in reproductive strategy.We found significant between-population variation in maternal body size and clutch mass,but these variations were not explained by elevational differences.However,high-elevation females tended to produce smaller clutches of larger eggs compared with their low-elevation counterparts,demonstrating an elevational change in the trade-off between egg size and number.The egg size-number trade-off is a reproductive strategy that may favor large offspring,better enabling them to survive severe and unpredictable environments found at high elevations.

Breeding biology of the Green-backed Tit(Parus monticolus)in southwest China

Studies on breeding biology enable us to broaden our understanding of the evolution of life history strategies.We studied the breeding biology of the Green-backed Tit(Parus monticolus)to provide comprehensive data on nest and egg characteristics,parental behavior throughout egg laying and nestling periods,and reproductive outcome.Our study reveals adaptive behavioral patterns and reproductive strategies for P.monticolus.

Reproductive Strategy and Cycle of the Toad-headed Agama Phrynocephalus grumgrzimailoi(Agamidae) in Xinjiang,China

The reproductive strategy and cycle of Phrynocephalus grumgrzimailoi were studied at a locality close to Urumqi City, Xinjiang, China. The hatchlings of P. grumgrzimailoi need at least two years to reach sexual maturity, with the smallest mature male and female measured 48.02 mm and 47.01 mm snout-vent length(SVL), respectively. Adult females produce a single clutch per breeding season, with the clutch size ranging from 1 to 5. The clutch size and mass are significantly correlated with female SVL. There is no correlation of mean egg size with clutch size and relative fecundity in P. grumgrzimailoi, suggesting that the trade-off is absent between mean egg size and number. Females increase reproductive output mainly through increasing egg numbers. The copulation period lasts from April to June. Females begin vitellogenesis in April and lay eggs from May to July. Our results suggest that toad-headed lizards tend to select different reproductive strategies to adapt themselves to their arid or semi-arid habitats.

Covariation in Insular Life-history Traits of the Rice Frog(Fejervarya limnocharis)in Eastern China

Although shifts in life-history traits of insular vertebrates, as compared with mainland populations, have been observed in many taxa, few studies have examined the relationships among individual life-history traits on islands. Lifehistory theory also predicts that there is a trade-off between body size and reproductive effort, and between egg size and clutch size. We surveyed the rice frog, Fejervarya limnocharis, on 20 islands within the Zhoushan Archipelago and two nearby sites on the mainland of China to compare differences in life-history traits and to explore relationships among those traits. Rice frog females reached a greater body size on half of the smaller islands among the total 20 surveyed islands, and larger egg size, decreased clutch size and reduced reproductive effort on most of the islands when compared to the two mainland sites. Insular body size was negatively correlated with reproductive effort. There was a negative correlation between egg size and clutch size. Results suggest that life-history theory provides a good explanation for co-variation between body size and reproductive effort, and between egg size and clutch size in rice frogs on the islands.

Experimental evidence that cuckoos preferentially parasitize host nests early in their laying cycle

Brood parasites,such as the Common Cuckoo(Cuculus canorus),rely on manipulating hosts from other species to raise their offspring.Selection should favor individuals that are able to identify and choose host nests that closely match the incubation stage of their own eggs.While intuitive,and supported by the findings of numerous longterm monitoring studies,experimental evidence of this remains sparse.By using video monitoring,we used three experimental groups to explore whether Common Cuckoos preferentially choose host Oriental Reed Warbler(Acrocephalus orientalis)nests that are early in their laying cycle.We found that Common Cuckoos preferentially parasitize nests of the host Oriental Reed Warbler that are earlier in their laying(less vs.more eggs)or nesting cycle(eggs vs.chicks),and videos of our experiments provide direct insights into their decision making process.Our results provide strong experimental evidence that Common Cuckoos are able to assess nesting stage and strategically choose nests that increase the likelihood of successful parasitism.

Avian sibling cannibalism: Hoopoe mothers regularly use their last hatched nestlings to feed older siblings

Sibling cannibalism is relatively common in nature,but its evolution in birds and certain other vertebrates with extended parental care had been discarded.Here,however,we demonstrate its regular occurrence in two European populations of the Eurasian hoopoe(Upupa epops)and explore possible adaptive and non-adaptive explanations.Results showed that sibling cannibalism was more frequently detected in Spain(51.7%)than in Austria(5.9%).In these two populations,the hoopoes laid similar clutch sizes,resulting in similar fledging production,but hatching failures were more frequent in the northern population.Consequently,having more nestlings condemned to die in the southern population may explain the higher incidence of sibling cannibalism.In accordance with this interpretation,hatching span and failure,but not breeding date,explained the probability of sibling cannibalism in the Spanish hoopoes,while all three variables predicted brood reduction intensity.Furthermore,experimental food supply reduced the probability of sibling cannibalism,but not the intensity of brood reduction.Finally,females allocated fewer resources to the smallest nestlings when they were going to starve,but not necessarily when they were going to be used as food for their siblings.These results suggest that hoopoes produce extra eggs that,in the case of reduced hatching failure and food scarcity,produce nestlings that are used to feed older siblings.These findings provide the first evidence that sibling cannibalism occurs regularly in a bird species,thus expanding our evolutionary understanding of clutch size,hatching asynchrony,parent-offspring conflict,infanticide,and sibling cannibalism in the animal kingdom.

Breeding biology of a relictual Maghreb Magpie(Pica mauritanica)population in Tunisia

Background:The Maghreb Magpie(Pica mauritanica)is an endemic North African species.Available knowledge on this species is limited to historic descriptive data with no ecological information provided.Populations continue to dramatically decline in Tunisia,where only one relic population survives.Investigating the breeding biology of this species is essential for conservation purposes.The purpose of this study was to increase our understanding of the Tunisian relic population and provide detailed data on breeding biology over two breeding seasons(2017 and 2018).Methods:This study occurred on a private farm of 650 ha,located 10 km from Dhorbania village at Kairouan Governorate,in central Tunisia.Active nests were monitored weekly during egg laying period and twice a week during hatching period.The Ivlev's electivity index was used to assess whether the frequency of use of nesting trees and bushes matched their availability in the study area.We recorded nest measurements and positions,and compared them using Wilcoxon signed-rank test.Variations of breeding parameters as number of eggs laid,hatchlings,and fledglings over years were performed using Mann–Whitney U-test andχ^(2) tests.We used a Generalized Linear Mixed Model(GLMM)to investigate how egg volume varied with clutch size and laying date.Results:We investigated clutch size,egg size,hatching and fledging success,and evaluated how these parameters varied according to laying date and nest characteristics.Clutch size averaged 5.00±0.19 but was significantly greater nest.Causes of nest failure included the depredation of nestlings by shrikes,cobras and rats(e.g.Lanius meridionalis,Naja haje and Rattus rattus),death of parents by the Black-shouldered Kite(Elanus caeruleus)and nest parasitism by the Great Spotted Cuckoo(Clamator glandarius).Clutch size,brood size and fledgling success were unaffected by laying date,nest volume and nest elevation.Egg volume decreased with laying date but was unaffected by clutch.Conclusion:Our study provides the first and only detailed data on reproductive parameters of the Maghreb Magpie in its entire geographic range(North Africa).Information gleaned from this study provides valuable information for monitoring and long-term conservation plans of the endangered Tunisian Magpie population.Additionally,our data provide an avenue of large-scale comparative studies of the reproductive ecology of the magpie complex.

Egg investment strategies adopted by a desertic passerine, the Saxaul Sparrow(Passer ammodendri)

Background:As one of the reproductive strategies adopted by bird species,variation in investment in egg production and its influencing factors are important and well-studied subjects.Intraclutch changes in egg size associated with laying order may reflect a strategy of"brood survival"or"brood reduction"adopted by female birds in different situations.Methods:We conducted field studies on the breeding parameters of the Saxaul Sparrow(Passer ammodendri)in Gansu Province,China from 2010 to 2017,to clarify the factors affecting the egg investment and reproductive performance of this passerine species.Results:Our results revealed significant differences in clutch size,egg size and the fledging rate between the first and second brood of Saxaul Sparrows and suggested that this typical desert species allocates more breeding resources to the more favourable second brood period,leading to greater reproductive output.Female body size presented a positive relationship with egg size,and male body size presented positive relationships with clutch size and hatchability.The females that started their clutches later laid more eggs,and hatchability and the fledging rate also increased with a later laying date in the first brood period.With successive eggs laid within the 5-egg clutches(the most frequent clutch size),egg size increased for the first three eggs and then significantly decreased.Conclusions:Our results indicate that female Saxaul Sparrows increased egg investment because of good quality of paired males and good environmental conditions.The intraclutch variation of egg size suggests that this species inhabiting an arid environment adopts a"brood reduction"strategy.

Selective extinction and habitat nestedness are the main drivers of lizard nestedness in the Zhoushan Archipelago

Nested subset pattern(nestedness)is an important part of the theoretical framework of island biogeography and community ecology.However,most previous studies often used nestedness metrics or randomization algorithms that are vulnerable to type I error.In this study,we inves-tigated the nestedness of lizard assemblages on 37 islands in the Zhoushan Archipelago,China.We used the line-transect method to survey species occurrence,abundance,and habitat types of lizards on 37 islands during 2 breeding seasons in 2021 and 2022.We applied the nested metric WNODF and the conservative rc null model to control for type I error and quantify the significance of nestedness.Spearman rank cor relations were used to evaluate the role of 4 habitat variables(island area,2 isolation indices,and habitat diversity)and 4 ecological traits(body size,geographic range size,clutch size,and minimum area requirement)in generating nestedness.The results of WNODF analyses showed that lizard assemblages were significantly nested.The habitat-by-site matrix estimated by the program NODF was also significantly nested,support-ing the habitat nestedness hypothesis.The nestedness of lizard assemblages were significantly correlated with island area,habitat diversity.clutch size,and minimum area requirement.Overall,our results suggest that selective extinction and habitat nestedness were the main drivers of lizard nestedness in our system.In contrast,the nestedness of lizard assemblages was not due to passive sampling or selective colonization.To maximize the number of species preserved,our results indicate that we should protect both large islands with diverse habitats and species with largearea requirement and clutch size.

Does insect mother know under what conditions it will make their offspring live？

According to the optimal oviposition theory, the larval success of insects depends on the oviposition site selection by females. Females are expected to choose a site with many resources and few competitors or predators to allow the best performance for their progeny, assuming that ＂mother knows best.＂ However, this is not systematically observed. The Aphidoletes aphidimyza larvae are generalist aphid predators and females consequently lay their eggs near or inside aphid colonies. The goal of this study was to investigate the impact ofintraspecific competition on oviposition behavior of A. aphidimyza females. First, we counted the number of eggs laid by a female on a leaf with 20 aphids, in the presence of 0, 2, 4, or 6 conspecific eggs or in the absence of eggs but in presence of 3 virgin females. The same experiment was also performed under choice condition with 2 oviposition sites. Our results show that the presence of low densities ofconspecific eggs, or the presence of conspecific females, have no significant impact on the number of eggs laid by A. aphidimyza females. One of the hypotheses advanced to explain these results is the advantages of conspecifics presence. At low densities, the presence of eggs on an oviposition site can indicate the suitability of the site for the females. The conspecific presence can also insure a dilution effect against predator and increase the presence of potential mating partners for this monogenic species.

Latitudinal and seasonal variation in reproductive effort of the eastern fence lizard (Sceloporus undulatus)

Geographic variation in life-history traits among populations of wide-ranging species is influenced by both spa­tial and temporal aspects of the environment. Rarely, however, are the effects of both aspects examined concur­rently. We collected gravid female lizards (Sceloporus undulatus) from northern (Indiana), central (Mississippi) and southern (Florida) populations, spanning nearly the full latitudinal range of the species, to examine among-population differences in strategies of reproductive energy allocation. Adult females from the southern popula­tion were smaller, and produced fewer and smaller eggs in their first clutches than did females from the more northern populations. Southern females were more likely to produce a second clutch, and second clutches were smaller than first clutches for females from the 2 northern populations. Together these trends eliminated popu­lation differences in overall reproductive output after accounting for body size. The trend for greater reproduc­tive energy to be allocated to first clutches at higher latitudes, and to later clutches at lower latitudes is corrobo­rated by published data from field studies on multiple populations. Distributing reproductive effort by producing more clutches of smaller eggs may be an adaptive response to the long season available for egg incubation and lizard activity in sub-tropical southern environments. In contrast, allocating greater resources to early reproduc­tion may enhance maternal fitness in the relatively short activity seasons that characterize more northern sites.

Nest-site selection of the White Eared pheasant in southwestern Sichuan Province,China

From April to July 2003 and 2004,we surveyed the nest-site selection of the White Eared pheasant(Crossoptilon crossoptilon)in the Zhujie Monastery and in the mountain facing it in Sichuan Province,China.In this paper,we studied the nest characteristics and the clutch size of the pheasant.Habitat sampling method was used to determine the variables that might affect the nest-site selection of the White Eared pheasant.Chi-square test was used to identify which habitat type was likely to be preferred by the bird.Independent-samples t test and Mann–Whitney U test were used to find which variables were important for the birds’nest-site selection.A total of 13 nests were found.Oak shrub was greatly preferred as nest sites(84.62%).Nests under a rock wall(7.69%)and a fallen tree(7.69%)were also found.The average clutch size of a White Eared pheasant is 7.33±0.54(range,5–11;n=12).Laying period was between April 27 and May 21.In the Zhujie area,1 nest was in the forest and 11 nests were in oak shrubs.The species preferred oak shrub as its nesting habitat(χ^(2)=8.333,df=1,P<0.05).The bird was more likely to place its nest in sites with a high coverage,i.e.0.5,1,and 2 m above the ground(independent-samples t test,P<0.05),and with a large shrub diameter(Mann–Whitney U test,P<0.05).The species are more likely to prefer sites with plant cover,shrub cover(independentsamples t test,P<0.05),and shrub height(Mann–Whitney U test,P<0.05)in a relatively small range.