Inter-individual variation in provisioning rate,prey size and number,and links to total prey biomass delivered to nestlings in the Collared Flycatcher(Ficedula albicollis)

Background:In bird species where offspring growth and survival rely on parents’food provisioning,parents can maximise their fitness by increasing the quantity and/or the quality of preys delivered to their offspring.Many studies have focused on inter-individual variation in feeding rate,yet this measure may not accurately reflect the total amount of food(i.e.energy)provided by parents if there is large variation in the quantity and quality of preys at each feeding.Here,we explored the relative role of individual(sex,age,body condition),breeding(hatching date,brood size)and environmental(temperature)factors on feeding rate,prey number,size and quality,and their contribution to total prey biomass delivered to the nestlings of 164 Collared Flycatcher(Ficedula albicollis)parents in 98 nests.Results:Preys delivered to the nest were mainly larvae(53.6%)and flying insects(45.6%).Feeding rate increased with brood size and age,and was higher in males than females.Mean prey number decreased,but mean prey size increased,as the season progressed and parents feeding their brood with primary larvae brought more preys per visit.Relationships between feeding rate,mean prey number and size remained when taking into account the provision-ing quality:parents brought either a large number of small prey or a small number of larger items,and the force of the trade-offs between feeding rate and mean prey number and size depended on the quality of the provisioning of the parents.Whatever the percentage of larvae among preys in the provisioning,the variance in total prey biomass was foremost explained by feeding rate(65.1%to 76.6%)compared to mean prey number(16.4%to 26%)and prey size(2.7%to 4%).Conclusions:Our study shows that variation in feeding rate,prey number,size,but not quality(i.e.percentage of lar-vae),were influenced by individual factors(sex and age)and breeding decisions(brood size and timing of breeding)and that,whatever the provisioning strategy adopted,feeding rate was the best proxy of the total biomass delivered to the nestlings.

Activation of Auditory Centers during Freezing Response Depends on Visual Afferentation in Course of the Development of Pied Flycatcher Nestlings

The study of defense behavior development in pied flycatcher altricial nestlings has shown that preceding visual deprivation decreased the capability to freeze in the young. At the same time, auditory thresholds of deprived nestlings were lower than those of the nestlings developing in unaltered visual environment. Our goal in the present work was to study effects of visual input on the functional development of neural circuitry for flycatcher’s acoustically-guided defensive behavior. We compared the immunohistochemical response of transcription factors ZENK and c-Fos in the nestlings’ auditory telencephalic structures in visually deprived and non-deprived flycatcher nestlings to alarm calls emitted by adult birds. We have demonstrated that the development of flycatcher nestlings under the conditions of limited visual afferentation results in the decrease of induction of the immediate-early genes c-Fos and ZENK in auditory structures of 9-day-old nestlings performing auditory-guided defense behavior. The most marked decrease of induction of both genes is observed in Field L. Our data suggest that visual afferentation affects neuronal activations in higher auditory structures of nestlings’ brain that, in turn, may increase the efficiency of species-typical alarm call. Thus, the work demonstrated for the first time that visual affererntation facilitates the growth of efficiency of alarm call affecting the activity of neurons in auditory integrative structures.

Mate choice for major histocompatibility complex(MHC)complementarity in the Yellow-rumped Flycatcher(Ficedula zanthopygia)

Background:Genes of the major histocompatibility complex(MHC)are an important component of the vertebrate immune system and play a significant role in mate choice in animal populations.However,the MHC genetic targets of female mate choice have not been clearly identified,and whether female mate choice is based on neutral genetic characteristics remains an open question.Here,we focus on the effects of morphological traits and genetic similarity among individuals in MHC class IIB(MHC IIB)exon 2 on mating in a sexually dimorphic songbird that exhibits social monogamy with extra-pair paternity(EPP).Methods:We sequenced 64 parent-offspring triads sampled over a 3-year period using two MHC class II loci to detect disassortative mating in the Yellow-rumped Flycatcher(Ficedula zanthopygia).Results:We found that MHC similarity in social pairs was lower than that in random pairs.Extra-pair mate choice according to MHC IIB was observed,in which females’extra-pair mates had fewer MHC alleles than their within-pair mates,but there was no significant band-sharing between extra-pair sires and potential extra-pair mates.However,the interaction between the MHC diversity of females and that of the social males affected the occurrence of EPP.Conclusions:Our results support the“optimality hypothesis”of MHC-based social and extra-pair choice.Female choice probably maintains a certain level of MHC diversity in offspring in the Yellow-rumped Flycatcher.

The Black-winged Monarch(Monarcha frater):Geographic variation,taxonomy,a"new"population,and an enduring mystery in migration

The Black-winged Monarch(Monarcha frater)inhabits low-mid elevation forests across New Guinea and far northeastern Australia.Of its four recognized subspecies,M.f.canescens is migratory,breeding in tropical north-eastern Australia from approximately November–March.The non-breeding range of M.f.canescens,apart from some individuals overwintering in Australia,has been unknown for>100 years.Data from 194 New Guinean and Australian specimens and a literature review have not solved this mystery;the narrow latitudinal range of the intratropical migration may inhibit use of GPS loggers in resolving the migration route.Field work in central and western parts of southern New Guinea is needed.Specimen data,however,revealed an essentially overlooked population in north-western New Guinea east of the Bird's Head Peninsula phenotypically indistinguishable from nominate M.f.frater of that Peninsula.Future genomic analysis of the complex will be largely done from toepad skin because frozen tissue samples for DNA analysis exist only of four individuals of what we suggest should be elevated to species rank as M.periophthalmicus.We discuss how genomic analysis might distinguish among alternative taxonomic hypotheses of one,two or three species.We suggest English names for what we consider to be three diagnosable taxa worth recognizing at species rank in this group:Arfak Monarch corresponding to M.frater(Bird's Head Peninsula and the“new”population of north-western New Guinea);Pearly Monarch for M.canescens(Australia and still unknown non-breeding range),and Masked Monarch for M.periophthalmicus(including kunupi,elsewhere in New Guinea).

Inorganic Elements in Eggs of Two Cavity-Nesting Passerine Species at and around Los Alamos National Laboratory, Los Alamos, New Mexico

Los Alamos National Laboratory (LANL) was established in 1943 as part of the Manhattan Project to build nuclear weapons, and currently operates as a national research laboratory. As part of an ongoing assessment of site-related ecological risk at LANL, western bluebird (Sialia mexicana) and ash-throated flycatcher (Myiarchus cinerascens) eggs were collected from 1997 to 2012 and analyzed for 18 inorganic elements. Concentrations of many inorganic elements in eggs were below reporting limits. Between species comparisons revealed that western bluebird eggs had higher levels of barium while ash-throated flycatcher eggs had higher levels of mercury. No statistically significant differences were observed in concentrations of inorganic elements in western bluebird eggs collected from the study area (which consists of areas within the current and historic LANL boundary) and from a non-industrial reference site;nor were any statistically significant differences observed between two canyons of interest, known to have received effluents and storm water runoff from LANL facilities, and the non-industrial reference site. Inorganic element levels detected in western bluebirds were typically within the range measured in eggs of other passerine in the published literature. These data suggest that concentrations of inorganic elements in passerine eggs collected from the study area appear to be at levels causing negligible risks to local bird populations.

Responses of incubating females to female cuckoo calls in 2 hole-nesting bird species

Acoustic signals play an important role in animal communication systems,and these signals can transfer diverse and meaningful information from a signaler to a receiver(e.g.,Yu et al.2019).Animal signals tend to be honest;however,deception can occur when it is beneficial for receivers to send dishonest signals,such as by mimicking alarm calls to steal food from other individuals(Flower et al.2014).In birds,vocal mimicry is a widespread phenomenon that has 2 major functional explanation categories:intraspecific and interspecific communications(Dalziell et al.2015).Vocal mimicry in intraspecific communication mainly involves sexual selection and social affiliation(Dalziell et al.2015).In interspecific communication,studies on vocal mimicry are mostly related to predator–prey interactions(Dalziell et al.2015).Mimics could mimic calls of predators to scare off other predators or competitors.For example,some species of hole-nesting birds produce a snakelike hissing call to drive nest predators away(e.g.,Dutour et al.2020).Receiver should be particularly sensitive to the deceptive vocals of mimics if failing to respond to an actual model sound is costly.Therefore,the mimics could derive an advantage from mimicking the calls of predators of the receivers.A recent experimental study suggested that the bubbling calls of female common cuckoo Cuculus canorus mimic those of Eurasian sparrowhawk Accipiter nisus,and they primarily serve to distract regular hosts after laying eggs(York and Davies 2017).However,Xia et al.(2019)found that female cuckoo calls have other functions,including attracting mates and repelling rivals.