Diurnal brooding behavior of long-tailed tits （Aegithalos caudatus glaucogularis）

Brooding is a major breeding investment of parental birds during the early nestling stage, and has important effects on the development and survival of nestlings. Investigating brooding behavior can help to understand avian breeding investment strategies. From January to June in 2013 and 2014, we studied the brooding behaviors of long-tailed tits （Aegithalos caudatus glaucogularis） in Dongzhai National Nature Reserve, Henan Province, China. We analyzed the relationships between parental diurnal brooding duration and nestling age, brood size, temperature, relative breeding season, time of day and nestling frequencies during brooding duration. Results showed that female and male long-tailed tit parents had different breeding investment strategies during the early nestling stage. Female parents bore most of the brooding investment, while male parents performed most of the nestling feedings. In addition, helpers were not found to brood nestlings at the two cooperative breeding nests. Parental brooding duration was significantly associated with the food delivered to nestlings （F=86.10, dr=l, 193.94, P〈0.001）, and was longer when the nestlings received more food. We found that parental brooding duration declined significantly as nestlings aged （F=5.99, dr=-1, 50.13, P=0.018）. When nestlings were six days old, daytime parental brooding almost ceased, implying that long- tailed tit nestlings might be able to maintain their own body temperature by this age. In addition, brooding duration was affected by both brood size （F=12.74, dr=-1,32.08, P=0.001） and temperature （F=5.83, df=-l, 39.59, P=-0.021）, with it being shorter in larger broods and when ambient temperature was higher.

An unusual homing behavior found in the Sichuan Partridge during the early brooding period

In this study,we report an unusual homing behavior of the Sichuan Partridge(Arborophila rufipectus)at the Laojunshan National Nature Reserve,Sichuan Province,China.Hen Sichuan Partridges led the chicks back to the nests where they hatched in the evening and roosted there over night.This behavior lasted 6.7±4.3 nights(range=1–15;n=13)after the chicks hatched.At this stage,the hens became very vigilant to predators and human disturbance.If disturbed,they often abandoned the nests immediately and no longer returned thereafter.The ambient temperature at night during the early brooding period of Sichuan Partridge at our study site was^12.4°C.Our findings suggest that hen Sichuan Partridges may make trade-offs between nest predation risks versus the thermoregulatory needs of their young.

Key Techniques of Artificial Incubation and Brooding of Bonasa bonasia

The key techniques of artificial incubation and brooding of Bonasa bonasia during breeding technology promotion was summed up in the paper.Electric incubation and dielectric incubation,electric brooding and dielectric brooding were compared with each other.The results showed that the effect of dielectric inoculation was poor,and there were no significant difference between electric brooding and dielectric brooding.

Double-brooding and annual breeding success of great tits in urban and forest habitats

Urban areas differ from natural habitats in several environmental features that influence the characteristics of animals living there.For example,birds often start breeding seasonally earlier and fledge fewer offspring per brood in cities than in natural habitats.However,longer breeding seasons in cities may increase the frequency of double-brooding in urban compared with nonurban populations,thus potentially increasing urban birds’annual reproductive output and resulting in lower habitat difference in reproductive success than estimated by studies focusing on first clutches only.In this study,we investigated 2 urban and 2 forests great tit Parus major populations from 2013 to 2019.We compared the probability of double-brooding and the total number of annually fledged chicks per female between urban and forest habitats,while controlling for the effects of potentially confounding variables.There was a trend for a higher probability of double-brooding in urban(44%of females)than in forest populations(36%),although this was not consistent between the 2 urban sites.Females produced significantly fewer fledglings annually in the cities than in the forest sites,and this difference was present both within single-and double-brooded females.Furthermore,double-brooded urban females produced a similar number of fledglings per season as single-brooded forest females.These results indicate that double-brooding increases the reproductive success of female great tits in both habitats,but urban females cannot effectively compensate in this way for their lower reproductive output per brood.However,other mechanisms like increased post-fledging survival can mitigate habitat differences in reproductive success.

A novel method to collect sperm from brood parasitic cuckoos:Urodeum stimulation(UroS)method

Sperm competition has been studied in numerous species as a representative example of postcopulatory sexual selection,where sampling sperm from male is the most basic and important step.Sperm collection can be tricky in birds,however,because unlike mammals,the genitals of birds are generally latent in the cloacal region and their characteristics vary among species.Various methods to collect sperm from different birds have been tested,such as cloacal massage,feces collection,and electro-stimulation,but their applicability varies depending on species.In this study,we introduced the urodeum stimulation method(UroS method)to collect sperm from Cuculus cuckoos,such as the Common Cuckoo(C.canorus).These species are expected to have interesting patterns of pair bonding and sperm competition because of their unique breeding strategy called brood parasitism;however,it remains unexplored.In this study,we described the application of our new method to expel semen from male common cuckoos,measured the volume of semen collected,checked the presence of sperm in the semen sample,and finally estimated its success rate among 82 males.Samples were successfully collected from 76 cuckoos(approximately 93%)and the colors and volumes of the samples were very diverse.Sperm was present in 43 of these samples(57%),showing a sperm observation rate approximately twice as high as that of the conventional cloacal massage method.We believe that this novel method will contribute to a better understanding of postcopulatory sexual selection in avian brood parasites and facilitate the process of sperm collection and artificial insemination in other medium-sized birds.

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.

Observation on behavior of adult oriental white stork in nesting period

Based on the field observation on the parental behavior of Oriental White Stork (Ciconia boyciana) during their brooding period, this paper describes the breeding style, feeding behavior, water chicks, protect chicks, etc. A Ritual “behavior—Culmen Knocking/bill clattering” was observed and which is divided into three styles with deferent meanings. This behavior plays an important role during this season.

Thoreau's philosophy of “simplify”

The essay expounds the philosophy of Thoreau's "simplify" in aspect of meaning and reason.Closely connected with the relationship between human and nature,it enables us to see the point of a brooding,simple and sensible life of Thoreau.The end clarifies on a question:according to Thoreau,what is to have a simplify life? That's to care for little,listen to one's heart and do what one likes.The conclusion comes with an advocation that people keep a simple life with little greed,and take it as an ulti mate cure for the bothering life of today.

Using the nematode Caenorhabditis elegans as a model animal for assessing the toxicity induced by microcystin-LR

Among more than 75 variants of microcystin （MC）, microcystin-LR （MC-LR） is one of the most common toxins. In this study, the feasibility of using Caenorhabditis elegans to evaluate MC-LR toxicity was studied. C. elegans was treated with MC-LR at different concentrations ranging from 0.1 to 80 μg/L. The results showed that MC-LR could reduce lifespan, delay development, lengthen generation time, decrease brood size, suppress locomotion behavior, and decreases hsp-16-2-gfp expression. The endpoints of generation time, brood size, and percentage of the population expressing hsp-16-2-gfp were very sensitive to 1.0μg/L of MC-LR, and would be more useful for the evaluation of MC-LR toxicity. Furthermore, the tissue-specific hsp-16-2-gfp expressions were investigated in MC-LR-exposed animals, and the nervous system and intestine were primarily affected by MC-LR. Therefore, the generation time, brood size, and hsp-16-2-gfp expression in C. elegans can be explored to serve as valuable endpoints for evaluating the potential toxicity from MC-LR exposure.

Hawk mimicry does not reduce attacks of cuckoos by highly aggressive hosts

Background: Resemblance to raptors such as hawks(Accipiter spp.) is considered to be an adaptive strategy of cuckoos(Cuculus spp.), which has evolved to protect cuckoos against host attacks. However, the effectiveness of the mimicry remains controversial, and is not yet fully studied for highly aggressive hosts.Methods: We evaluated the effectiveness of sparrowhawk(Accipiter nisus) mimicry by common cuckoos(Cuculus canorus) in oriental reed warblers(Acrocephaus orientalis), which are highly aggressive hosts. Using a both the single and the paired dummy experiment, defense behaviors and attack intensities of oriental reed warblers against common cuckoos, sparrowhawks and oriental turtle doves(Streptopelia orientalis) were assessed.Results: Oriental reed warblers exhibit strong nest defense behaviors, and such behaviors do not change with breeding stage(i.e., egg stage and nestling stage). Furthermore, assistance from conspecific helpers may increase attack intensities. However, they were deterred from mobbing overall by the presence of the hawk.Conclusions: Oriental reed warblers are able to distinguish cuckoos from harmless doves. However, they may be deterred from mobbing by the presence of the predatory hawk, suggesting hawk mimicry may be ineffective and does not reduce attacks of cuckoos by highly aggressive hosts.

Geographic variation in parasitism rates of two sympatric cuckoo hosts in China

Rates of brood parasitism vary extensively among host species and populations of a single host species. In this study, we documented and compared parasitism rates of two sympatric hosts, the Oriental Reed Warbler （Acrocephalus orientalis） and the Reed Parrotbill （Paradoxornis heudei）, in three populations in China. We found that the Common Cuckoo （Cuculus canorus） is the only parasite using both the Oriental Reed Warbler and Reed Parrotbill as hosts, with a parasitism rate of 22.4%-34.3% and 0%-4.6%, respectively. The multiple parasitism rates were positively correlated with local parasitism rates across three geographic populations of Oriental Reed Warbler, which implies that higher pressure of parasitism lead to higher multiple parasitism rate. Furthermore, only one phenotype of cuckoo eggs was found in the nests of these two host species. Our results lead to two conclusions： （1） The Oriental Reed Warbler should be considered the major host of Common Cuckoo in our study sites; and （2） obligate parasitism on Oriental Reed Warbler by Common Cuckoo is specialized but flexible to some extent, i.e., using Reed Parrotbill as a secondary host. Further studies focusing on egg recognition and rejection behaviour of these two host species should be conducted to test our predictions.

Function of note strings in Japanese Tit alarm calls to the Common Cuckoo:a playback experiment

Background: Birds produce alarm calls to convey information about threats. Some Passerine alarm calls consist of several note strings, but few studies have examined their function. Previous studies have shown that Japanese Tits(Parus minor) can alter the calling rate and number and combination of notes in response to predators. We previously found the combinations of note types in Japanese Tit alarm calls to be significantly different in response to the Sparrowhawk(Accipiter nisus) and Common Cuckoo(Cuculus canorus).Methods: Through playback experiments, we tested whether the note strings in Japanese Tit alarm calls to the Common Cuckoo have different functions in conveying information. The note strings of selected alarm calls were divided into the categories of C and D, and different calls were then constructed separately based on the two note string categories. Original alarm calls(C–D), C calls and D calls were played back to male Japanese Tits during the incubation period.Results: Male Japanese Tits had a significantly stronger response to C calls than to C–D calls, and they showed a significantly stronger response to both C and C–D calls than to D calls, suggesting that Japanese Tits discriminated between the C and D calls.Conclusions: Our study demonstrated that the C-and D-category note strings of Japanese Tit alarm calls to the Common Cuckoo have different functions, which supports the previous finding that different note strings in an alarm call can provide different information to receivers. However, the exact meanings of these note strings are not yet known, and further investigation is therefore required.

Does nest sanitation elicit egg rejection in an open-cup nesting cuckoo host rejecter?

Background: Nest sanitation behavior is one of the most important means to ensure high reproductive efficiency. In avian brood parasitism, nest sanitation behavior may be a pre-adaptation of host birds that allows them to identify the parasitic eggs, so that egg discrimination behavior may have evolved from nest sanitation behavior. However, whether nest sanitation behavior could improve egg rejection in cuckoo hosts was inconclusive.Methods: In this study, we investigated the relationship between nest sanitation and egg discrimination behavior in a potential cuckoo host, the Brown-breasted Bulbul(Pycnonotus xanthorrhous) with two experimental groups. In the first group, we added a blue, non-mimetic egg to the nest of the host, while in the second group we added a blue, non-mimetic egg and a peanut half-shell.Results: The results showed that in the first group, the probability of rejecting the non-mimetic eggs was 53.8%(n = 26 nests). In comparison, all of the Brown-breasted Bulbuls in the second group were able to rapidly remove the peanut shells from the nest, but only 52.6%(n = 19 nests) rejected the non-mimetic eggs. The rejection rates of the non-mimetic eggs in both experimental groups were not significantly different.Conclusions: Our study indicated that nest sanitation behavior of Brown-breasted Bulbuls did not influence their egg recognition and that egg discrimination ability of Brown-breasted Bulbuls was not directly related to nest sanitation behavior.

Comparing vocal structures of the parasitic and nonparasitic groups in Cuculinae

Background: Avian brood parasitism is a breeding strategy in which brood parasites lay their eggs in the nest of other species.This behavior is closely related to aspects of the biological evolution of the parasitic species such as reduced female body size and plumage color polymorphism.However,not much is known whether it is associated with the evolution of vocalization.Methods: We collected samples of the typical male calls of 67 species belonging to the sub?family Cuculinae.Using the calls,we measured five acoustic parameters for each samples to test the differences in vocal structures between parasitic and nonparasitic species.To control for potential phylogenetic effects,we also performed phylogenetic independent contrast analyses.Results: We found that vocal structures were relatively similar among the parasitic species with a tendency to simple and low?frequency calls.In addition,harmonic structures were observed more frequently in the nonparasitic group.Conclusions: Overall,these results support the idea that brood parasitic behavior with associated ecological condi?tions may play a role in vocal evolution,a better understanding of which may greatly improve our knowledge of vocal diversification in non?oscine birds.

The breeding biology of endemic Spectacled Parrotbill(Sinosuthora conspicillatus) in Lianhuashan National Nature Reserve, Gansu Province, China

Background: Life history traits play critical roles in population survival and evolution.Breeding information should be particularly detailed in order to provide significant insights into the population status and the evolution of other traits.To our knowledge, there is still no information about the breeding biology of Spectacled Parrotbill(Sinosuthora conspicillatus), an endemic parrotbill in China.Methods: We searched the nests, checked all nests found and recorded the information of eggs, nestlings and nest sites of the Spectacled Parrotbill from 2013 to 2015 at Lianhuashan National Nature Reserve in Gansu Province, China.Results: A total of 16 nests were found.Nest trees were artificial young spruces and honeysuckles.Mean nest height was 0.89 ± 0.47 m(n = 16) above the ground level.All nests were cup-shaped and constructed using leaves, fine strips of barks and grasses by both parents.The mean clutch size was 4.42 ± 0.79(n = 12).The eggs were oval in pale blue without speckles, and the mean egg mass was 1.25 ± 0.07 g(n = 27).The egg length was 15.56 ± 0.46 mm(n = 27) and the width was 12.46 ± 0.29 mm(n = 27).Incubation period was 13 days and nestling period was 13–14 days.The breeding success rate was 46%, and among those failed nest, 71% were depredated and 29% were deserted.Conclusion: Detailed life history information about parrotbill is still limited.The breeding biology of Spectacled Parrotbill reported in the present study should be helpful for further research about population, breeding behavior and conservation of this bird.

Brood sex ratio in the Yellow-bellied Prinia(Prinia flaviventris)

Background:The adjustment of sex ratios in birds can occur at the egg and nestling stages. Previous studies showed that the sex ratio was affected by environmental factors and parental condition; it may result in seasonal and ecosystem differences.Methods:In this study, the brood sex ratio of the Yellow-bellied Prinia(Prinia flaviventris) in the Nonggang area, Guangxi, southwestern China, was investigated during the breeding season from May to June in 2013 using PCR amplification from whole-genome DNA extracted from blood samples. A total of 31 nests of Yellow-bellied Prinia, including 132 brood fledglings and 31 pairs, were sampled.Results:The results showed that the brood sex ratio of the Yellow-bellied Prinia was 1:1, and sex ratios of different nests were evenly distributed within the study area. No significant relationship was found between parental quality and nest characteristics with the brood sex ratio.Conclusions:The present study indicated that no brood sex ratio bias in the Yellow-bellied Prinia highlighted the complexity of sex ratio adjustment in birds. In spite of our negative results, the lack of an association between brood sex ratio and parental quality and environmental factors in the Yellow-bellied Prinia provides valuable information on the adjustment of sex ratios in birds.

Roles of interleukins in antibacterial immune defense of the brood pouch in the lined seahorse Hippocampus erectus

Seahorse embryos are brooded in the enclosed nutrient-rich environment of the male brood pouch,which may be prone to bacterial infection.The immune responses of interleukin(IL)genes in the brood pouch have not been well studied.We identifi ed 13 interleukins in the lined seahorse Hippocampus erectus.Tissue-specifi c expression analysis revealed increased mRNA expression levels of il-1β,il-18,and il-8 in the brood pouch.When challenged with lipopolysaccharide or Vibrio parahaemolyticus,il-1βand il-18 were active as part of the acute and chronic infl ammatory responses,respectively.Importantly,il-8 may be involved in powerful antibacterial immune responses and may be induced by il-1βand il-18 via a process involving the nuclear factor-κB signaling pathway.These results suggest that il-1β,il-18,and il-8 may play key roles in the antibacterial immune defense of the brood pouch in male seahorses.

Light matters:Nest illumination alters egg rejection behavior in a cavity-nesting bird

Egg discrimination by cavity-nesting birds that build nests under dim light conditions was presumed to depend on nest luminance,although this hypothesis has rarely been tested.Tests of egg discrimination ability by cavity-nesting tits under dim light conditions may reveal the selection pressure from brood parasitism that they encounter under natural interactions.We manipulated the intensity of luminance of nests of the Green-backed Tit(Parus monticolus),a potential cuckoo host that possesses a strong discrimination ability of non-mimetic foreign eggs.We performed experiments to test their egg discrimination ability under different light conditions.Our results showed that Green-backed Tits discriminate against non-mimetic foreign eggs under normal light conditions in nest boxes,and this ability persisted at nest luminance as low as 4.78±1.31 lux that is several times lower than normal luminance(38.11±24.02 lux).However,egg discrimination by Green-backed Tits disappeared when nest luminance was reduced to a minimum of 0.35±0.15 lux.The latter value represents total darkness for humans.The present study shows that nest luminance plays a key role in egg discrimination by Green-backed Tits that build nests under dim light conditions.This study provides strong experimental evidence for nest illumination altering egg rejection behavior in cavity-nesting birds.

Development and behavior of Plaintive Cuckoo(Cacomantis merulinus) nestlings and their Common Tailorbird(Orthotomus sutorius) hosts

Background:Our knowledge of avian brood parasitism is primarily based on studies of a few selected species.Recently,researchers have targeted a wider range of host–parasite systems,which has allowed further evaluation of hypotheses derived from well-known study systems but also disclosed adaptations that were previously unknown.Here we present developmental and behavioral data on the previously undescribed Plaintive Cuckoo(Cacomantis merulinus) nestling and one of its hosts,the Common Tailorbird(Orthotomus sutorius).Methods:We discovered more than 80 Common Tailorbird nests within an area of 25 km2,and we recorded nestling characteristics,body mass,tarsus length and begging display every 3 days for both species.Results:Plaintive Cuckoo nestlings followed a developmental pathway that was relatively similar to that of their well-studied relative,the Common Cuckoo(Cuculus canorus).Tailorbird foster siblings were evicted from the nest rim.The cuckoo nestlings gained weight faster than host nestlings,and required 3–9 days longer time to fledge than host nestlings.Predation was high during the early stages of development,but the nestlings acquired a warning display around 11 days in the nest,after which none of the studied cuckoo nestlings were depredated.The cuckoos' begging display,which appeared more intense than that of host nestlings,was initially vocally similar with that of the host nestlings but began to diverge from the host sound output after day 9.Conclusions:The developmental data on Plaintive Cuckoo nestlings and their tailorbird host builds an important foundation for future work on the co-evolutionary interactions in this parasite–host system.

Egg recognition in Cinereous Tits(Parus cinereus):eggshell spots matter

Background:Brood parasitic birds such as cuckoos(Cuculus spp.)can reduce their host’s reproductive success.Such selection pressure on the hosts has driven the evolution of defense behaviors such as egg rejection against cuckoo parasitism.Studies have shown that Cinereous Tits(Parus cinereus)in China have a good ability for recognizing foreign eggs.However,it is unclear whether egg spots play a role in egg recognition.The aims of our study were to investigate the egg recognition ability of two Cinereous Tit populations in China and to explore the role of spots in egg recognition.Methods:To test the effect of eggshell spots on egg recognition,pure white eggs of the White-rumped Munia(Lonchura striata)and eggs of White-rumped Munia painted with red brown spots were used to simulate experimental parasitism.Results:Egg experiments showed that Cinereous Tits rejected 51.5%of pure white eggs of the White-rumped Munia,but only 14.3%of spotted eggs of the White-rumped Munia.There was a significant difference in egg recognition and rejection rate between the two egg types.Conclusions:We conclude that eggshell spots on Cinereous Tit eggs had a signaling function and may be essential to tits for recognizing and rejecting parasitic eggs.