Crotophaga Ani Research Articles

Offspring sex ratio in a communal breeding bird is male‐biased when pre‐breeding rainfall is low

Offspring sex ratios may deviate from parity when the fitness benefits of producing male or female offspring vary. We tested for sex ratio bias in smooth‐billed anis Crotophaga ani, a communal laying cuckoo with low within‐group relatedness and high offspring dispersal. One male group member performs nocturnal incubation and sires more offspring than other males in the group, suggesting males may have greater reproductive variance than females. We hypothesized that pre‐breeding rainfall influences food availability and offspring sex ratio, predicting that breeding females skew production towards the sex with higher reproductive variance (males) in high food years. Females may also adjust sex ratio across the hatching order to increase survival of the more competitive sex, especially when clutches are larger and within‐brood competition is higher. As adults, male smooth‐billed anis are larger than females, so we assumed male nestlings are more competitive than females and predicted a male‐bias in first hatched chicks in larger broods. Contrary to our first prediction, offspring sex ratio was male biased when pre‐breeding rainfall was lower. In partial support of our second prediction, marginally more first hatched chicks were male in larger broods. To our knowledge, this is the first evidence of offspring sex ratio bias in a communal laying bird species. Future work in this system will attempt to uncover the mechanisms by which co‐breeding females adjust offspring sex ratio and test alternative hypotheses to explain male‐biased offspring sex ratios under different conditions.

Understanding the chromosomal evolution in cuckoos (Aves, Cuculiformes): a journey through unusual rearrangements.

The Cuculiformes are a family of over 150 species that live in a range of habitats, such as forests, savannas, and deserts. Here, bacterial artificial chromosome (BAC) probes (75 from chicken and 14 from zebra finch macrochromosomes 1-10 +ZW and for microchromosomes 11-28 (except 16)) were used to investigate chromosome homologies between chicken and the squirrel cuckoo (Piaya cayana). In addition, repetitive DNA probes were applied to characterize the chromosome organization and to explore the role of these sequences in the karyotype evolution of P. cayana. We also applied BAC probes for chicken chromosome 17 and Z to the guira cuckoo (Guira guira) to test whether this species has an unusual Robertsonian translocation between a microchromosome and the Z chromosome, recently described in the smooth-billed ani (Crotophaga ani). Our results revealed extensive chromosome reorganization with inter- and intrachromosomal rearrangements in P. cayana, including a conspicuous chromosome size and heterochromatin polymorphism on chromosome pair 20. Furthermore, we confirmed that the Z-autosome Robertsonian translocation found in C. ani is also found in G. guira, not P. cayana. These findings suggest that this translocation occurred prior to the divergence between C. ani and G. guira, but after the divergence with P. cayana.

Chemical Profiles Differ between Communal Breeding Groups in a Highly Social Bird.

AbstractGregarious species must distinguish group members from nongroup members. Olfaction is important for group recognition in social insects and mammals but rarely studied in birds, despite birds using olfaction in social contexts from species discrimination to kin recognition. Olfactory group recognition requires that groups have a signature odor, so we tested for preen oil and feather chemical similarity in group-living smooth-billed anis (Crotophaga ani). Physiology affects body chemistry, so we also tested for an effect of egg-laying competition, as a proxy for reproductive status, on female chemical similarity. Finally, the fermentation hypothesis for chemical recognition posits that host-associated microbes affect host odor, so we tested for covariation between chemicals and microbiota. Group members were more chemically similar across both body regions. We found no chemical differences between sexes, but females in groups with less egg-laying competition had more similar preen oil, suggesting that preen oil contains information about reproductive status. There was no overall covariation between chemicals and microbes; instead, subsets of microbes could mediate olfactory cues in birds. Preen oil and feather chemicals showed little overlap and may contain different information. This is the first demonstration of group chemical signatures in birds, a finding of particular interest given that smooth-billed anis live in nonkin breeding groups. Behavioral experiments are needed to test whether anis can distinguish group members from nongroup members using odor cues.

Predation on a Roughskin Anole (Anolis trachyderma) by a Smooth-billed Ani (Aves: Cuculidae)

Predation on a Roughskin Anole (Anolis trachyderma) by a Smooth-billed Ani (Aves: Cuculidae)

Symbiotic microbiota vary with breeding group membership in a highly social joint-nesting bird

Abstract Symbiotic microbes affect the health, fitness, and behavior of their animal hosts, and can even affect the behavior of non-hosts. Living in groups presents numerous benefits and challenges to social animals, including exposure to symbiotic microbes, which can mediate both cooperation and competition. In social mammals, individuals from the same social group tend to share more similar microbes and this social microbiome, the microbial community of all hosts in the same social group, can shape the benefits and costs of group living. In contrast, little is known about the social microbiome of group living birds. We tested the predictions that communally breeding smooth-billed anis (Crotophaga ani) belonging to the same breeding group share more similar microbes and that microbial community composition differs between body regions. To test this, we used 16S rRNA gene sequencing to characterize the preen gland and body feather microbiota of adult birds from 16 breeding groups at a long-term study site in southwestern Puerto Rico. As predicted, individuals from the same breeding group shared more similar microbiota than non-group members and preen gland and body feathers harbored distinct microbial communities. Future research will evaluate whether this social microbiome affects the behavior of group living birds.

A 10-year collection of roadkilled avifauna in a stretch of the BR-040 highway in southeastern Brazil

ABSTRACT In Brazil, the number of animals killed by vehicle collision surpasses 475 millions/year, but the actual number may be even higher since roadkill data in the country is scarce and punctual. Using a standard protocol, the project Caminhos da Fauna monitored since 2006 the avifauna roadkill in the BR-040 (RJ/MG) highway, southeastern Brazil. Here, we present a checklist of the avifauna registered during the 10-year monitoring program, including the list of roadkills, indicating threatening status at regional, national, and global levels, and the number of records/species. We registered 1,317 individuals belonging to 180 species, 21 orders, and 48 families. Another 247 individuals could not be identified. For seven families roadkills were higher than 50 individuals: Thraupidae, Cuculidae, Strigidae, Tyrannidae, Psittacidae, Columbidae, and Turdidae. The most collected species were Crotophaga ani (n = 106; Cuculidae), followed by Psittacara leucophthalmus (n = 61; Psittacidae), Piaya cayana (n = 56; Cuculidae), and Asio clamator (n = 44; Strigidae). Five species were under threat: Penelope obscura, Primolius maracana, Pteroglossus bailloni, Ramphastos vitellinus, and Sicalis flaveola. Most species were geographically widespread, while other 13 (7.2%) were endemic. Given the considerable amount of data obtained, further efforts of the same motivation in other Brazilian roads and express transportation systems should be encouraged.

Nesting Success and Nesting Height in the Critically Endangered Medium Tree Finch (Camarhynchus pauper)

When different introduced species across trophic levels (parasite, predator) invade island systems, they may pose significant threats to nesting birds. In this study, we measure nesting height and infer causes of offspring mortality in the critically endangered Medium Tree Finch (Camarhynchus pauper), an island endemic restricted to Floreana Island on the Galápagos Archipelago. Considering all nests at which a male built a nest, sang and attempted to attract a female (n = 222 nests), only 10.4% of nests produced fledglings (5% of nests had total fledging success, 5.4% of nests had partial fledging success). Of the 123 nests chosen by a female, 18.7% produced fledglings and of 337 eggs laid, 13.4% produced fledglings. Pairing success was higher for older males, but male age did not predict nesting success. All nests with chicks were infested with avian vampire fly larvae (Philornis downsi). We attributed the cause of death to avian vampire fly if chicks were found dead in the nest with fly larvae or pupae (45%) present. We inferred avian (either Asio flammeus galapagoensis or Crotophaga ani) predation (24%) if the nest was empty but dishevelled; and black rat (Rattus rattus) predation (20%) if the nest was empty but undamaged. According to these criteria, the highest nests were depredated by avian predators, the lowest nests by rats, and intermediate nests failed because of avian vampire fly larvae. In conclusion, there is no safe nesting height on Floreana Island under current conditions of threats from two trophic levels (introduced parasitic dipteran, introduced mammalian/avian predators; with Galápagos Short-Eared Owls being the only native predator in the system).

Can guava monocultures (Psidium guajava L.) function as refuge for bird conservation?

Agricultural intensification negatively affects bird communities, and the response of birds to these changes varies from those that survive and increase their populations (disturb-tolerant species) to those that cannot adapt to new conditions and are regionally extinct (disturb-sensitive species). Thus, the present study sought to investigate the bird community in 39 guava orchards in the semiarid region of the state of Sergipe, northeast Brazil. Field observations were made between July and October 2017, through a one-hour visit to each orchard. Samplings were conducted using the MacKinnon’s List method. In addition to bird sampling, walks were carried out in the orchards to observe nesting. Seventy-six species of birds belonging to 30 families were recorded using the guava orchards. The most frequent species wereVanellus chilensis,Columbina talpacoti,Columbina picui,Crotophaga ani,Pitangus sulphuratusandSporophila albogularis. Of the 186 nests recorded in the orchards, the majority (n = 144 nests; 77.4%) belonged toColumbina picui,Columbina talpacotiandColumbina minuta. The results demonstrate that the bird community in the guava orchards is formed only by disturb-tolerant species, showing that the studied guava orchards are not favorable to the conservation of disturb-sensitive birds of the Caatinga domain.

Vocal repertoire and group-specific signature in the Smooth-billed Ani, Crotophaga ani Linnaeus, 1758 (Cuculiformes, Aves)

Vocal plasticity reflects the ability of animals to vary vocalizations according to context (vocal repertoire) as well as to develop vocal convergence (vocal group signature) in the interaction of members in social groups. This feature has been largely reported for oscine, psittacine and trochilid birds, but little has been investigated in birds that present innate vocalization. The smooth-billed ani (Crotophaga ani) is a social bird that lives in groups between two and twenty individuals, and which presents innate vocalization. Here we analyzed the vocal repertoire of this species during group activities, and further investigated the existence of a vocal group signature. The study was conducted in the Southeast of Brazil between May 2017 and April 2018. Two groups of smooth-billed anis were followed, Guararema and Charqueada groups, and their vocalizations were recorded and contextualized as to the performed behavior. The vocal repertoire was analyzed for its composition, context and acoustic variables. The acoustic parameters maximum peak frequency, maximum fundamental frequency, minimum frequency, maximum frequency and duration were analyzed. To verify the vocal signature of the group, we tested whether there was variation in the acoustic parameters between the monitored groups. We recorded ten vocalizations that constituted the vocal repertoire of the Smooth-billed Ani, five of which (“Ahnee”, “Whine”, “Pre-flight”, “Flight” and “Vigil”) were issued by the two groups and five exclusive to the Charqueada group. There were significant differences in the acoustic parameters for “Flight” and “Vigil” vocalizations between the groups, suggesting vocal group signature for these sounds. We established that the Smooth-billed Ani has a diverse vocal repertoire, with variations also occurring between groups of the same population. Moreover, we found evidence of vocal group signature in vocalizations used in the context of cohesion, defense and territory maintenance.

The El Niño – Southern Oscillation dramatically influences the probability of reproduction and reproductive rate of a tropical forest bird

Although climate change has been implicated in population declines of tropical forest birds, there is a critical lack of data on the mechanisms underlying these declines. Attempts to link climatic factors to variation in adult survival, fecundity or nest success have been largely inconclusive. Recent community‐scale analyses have suggested that tropical birds may be less likely to breed under adverse conditions, but long‐term data on individual reproduction are needed to test this hypothesis. Here we leverage 12 years of data on a lowland forest bird, the greater ani Crotophaga major, to investigate how demographic parameters vary with phase of the El Niño – Southern Oscillation (ENSO), a major driver of climatic conditions in tropical wet forest. The likelihood of breeding and annual reproductive rate both decreased dramatically in El Niño‐like years, with only 37.5% of adults attempting breeding in 2015 (a strong El Niño year). For birds that did breed, however, clutch size and daily nest predation rate were unaffected by climate. Of the local climate variables investigated, dry season length and the frequency of high temperatures were most closely associated with reproductive failure. These results indicate that El Niño conditions alter the demography of greater anis by reducing the likelihood of reproduction, a response that may be more widespread than currently recognized. We suggest that reduced reproduction under adverse conditions represents an important and understudied aspect of the life histories of tropical forest birds.

Chromosomal Analysis in Crotophaga ani (Aves, Cuculiformes) Reveals Extensive Genomic Reorganization and an Unusual Z-Autosome Robertsonian Translocation.

Although cytogenetics studies in cuckoos (Aves, Cuculiformes) have demonstrated an interesting karyotype variation, such as variations in the chromosome morphology and diploid number, their chromosome organization and evolution, and relation with other birds are poorly understood. Hence, we combined conventional and molecular cytogenetic approaches to investigate chromosome homologies between chicken and the smooth-billed ani (Crotophaga ani). Our results demonstrate extensive chromosome reorganization in C. ani, with interchromosomal rearrangements involving macro and microchromosomes. Intrachromosomal rearrangements were observed in some macrochromosomes, including the Z chromosome. The most evolutionary notable finding was a Robertsonian translocation between the microchromosome 17 and the Z chromosome, a rare event in birds. Additionally, the simple short repeats (SSRs) tested here were preferentially accumulated in the microchromosomes and in the Z and W chromosomes, showing no relationship with the constitutive heterochromatin regions, except in the W chromosome. Taken together, our results suggest that the avian sex chromosome is more complex than previously postulated and revealed the role of microchromosomes in the avian sex chromosome evolution, especially cuckoos.

Contribución al conocimiento de la distribución de aves poco comunes de los talares del noreste de la provincia de Buenos Aires

En el marco de un programa de monitoreo de las aves que utilizan los talares del noreste de la provincia de Buenos Aires como sitio de nidificación, presentamos registros de aves poco comunes en este hábitat y brindamos información sobre las fechas y tipo de hábitat donde se produjeron estos registros. Nos enfocamos en especies cuya distribución no incluye regularmente a los talares del noreste bonaerense (Halconcito Gris Spiziapteryx circumcincta, Tingazú Piaya cayana, Carpintero Blanco Melanerpes candidus, Anó Chico Crotophaga ani, Loro Choclero Pionus maximiliani, Catita Chirirí Brotogeris chiriri, Atajacaminos Tijera Hydropsalis torquata y Viudita Blanca Fluvicola albiventer) y de este modo contribuir con datos de campo para una mejor comprensión de la distribución de estas especies de aves.

Identification of two novel adenoviruses in smooth-billed ani and tropical screech owl.

Avian adenoviruses (AdVs) are a very diverse group of pathogens causing diseases in poultry and wild birds. Wild birds, endangered by habitat loss and habitat fragmentation in the tropical forests, are recognised to play a role in the transmission of various AdVs. In this study, two novel, hitherto unknown AdVs were described from faecal samples of smooth-billed ani and tropical screech owl. The former was classified into genus Aviadenovirus, the latter into genus Atadenovirus, and both viruses most probably represent new AdV species as well. These results show that there is very limited information about the biodiversity of AdVs in tropical wild birds, though viruses might have a major effect on the population of their hosts or endanger even domesticated animals. Surveys like this provide new insights into the diversity, evolution, host variety, and distribution of avian AdVs.

FIRST RECORD OF VOCAL MIMICRY IN SCARLET-HEADED BLACKBIRD Amblyramphus holosericeus (AVES: PASSERIFORMES) IN THE SOUTHEASTERN BRAZIL

Vocal mimicry is the ability of some bird species to copy heterospecific vocalizations in order to establish deceptive or non-deceptive interactions between an emitter and a receiver. This kind of vocal behavior is well documented in several species of New World Blackbirds (Icteridae family), but not in Scarlet-headed Blackbird ( Amblyramphus holosericeus ). Here we report the first event of vocal mimicry of this species, where a single individual imitated the vocal signals of Smooth-billed Ani ( Crotophaga ani ; Cuculiformes, Cuculidae). We argue that such behavior could have a deceptive role, increasing the predation avoidance and foraging efficiency of A. holosericeus by luring heterospecific individuals to form a mixed-flock.

Drought leads to reproductive quiescence in smooth‐billed anis: Phenotypic evidence for opportunistic breeding and reproductive readiness

Previous studies have suggested that the smooth-billed ani (Crotophaga ani, Linnaeus, 1758) breeds opportunistically following unpredictable rainfall in drought areas. To obtain proof of this phenomenon, the present study described and compared reproductive morphology and cell proliferation in the gonads of free-living smooth-billed anis during a wet season (April to June 2012) and the following dry season (July to September 2012) in a semiarid area using light and electron microscopy (transmission and scanning) and the AgNOR method. The morphological findings indicated distinct levels of reproductive activity related to seasonal changes. Morphological and morphometric analyses of the gonads confirmed intense gametogenic activity during the wet season, whereas gonadal involution occurred after rainfall ceased. The sizes of the testes and ovaries were significantly reduced compared to those in the wet season. The volumetric fraction of the seminiferous tubules in the testis decreased considerably, and no preovulatory follicles were detected in the ovary in the dry season. Moreover, the AgNOR count in the gonads revealed a significant decline in cell recruitment for gametogenesis after rainfall ceased. The histological findings indicated partial gonadal activation throughout the dry season. The analysis of the seminiferous epithelium confirmed the early testicular recrudescence phase, and sporadic postovulatory follicles indicated random ovulation during this time. The excurrent ducts and the oviduct also underwent remarkable involution in the dry season. Taken together, these findings confirm opportunistic breeding by smooth-billed anis in a semiarid habitat and suggest that gonadal recrudescence has been established as a reproductive strategy to cope with unexpected precipitation events.

The perceptual and chemical bases of egg discrimination in communally nesting greater anis Crotophaga major

The eggshells of communally breeding greater anis Crotophaga major consist of a blue‐green pigmented calcite matrix overlaid by a chalky white layer of vaterite, both of which are polymorphs of calcium carbonate. The white vaterite layer is intact in freshly laid eggs and may function in protecting the eggs from mechanical damage, but it also abrades during incubation to reveal the blue calcite shell underneath. Previous research has shown that this color change serves a visual signaling function: nesting greater anis can discriminate between eggs that are freshly laid and those that have already been incubated, which allows them to reject asynchronous eggs laid by extra‐group parasites. Here we use avian visual modeling and pigment extraction to assess the perceptual and chemical bases of such egg recognition. We found that there was no overlap between the avian perceptual space occupied by ani eggshells with and without vaterite, and that vaterite lacked both of the pigments found in the eggshell's calcite matrix, bililverdin and protoporphyrin. The visual contrast between the unpigmented vaterite and the blue‐pigmented calcite appears to pre‐date the evolution of the signaling function, since the related guira cuckoo Guira guira, also a communal breeder, lays similarly structured and pigmented eggs but does not use the visual contrast as a signal to detect parasitism.

Testing for sentinel coordination in Smooth-billed Anis (Crotophaga ani)

Sentinel behaviour has been widely described, but whether or not it is coordinated among group members requires careful examination. The Smooth-billed Ani, Crotophaga ani, a joint-nesting cooperatively breeding bird, appears to have a sentinel system; however, it is unknown whether that vigilance is coordinated, the defining feature of sentinel behaviour. We followed social groups during two breeding seasons to observe and time their individual sentinel bouts. We then tested for coordination by quantifying the observed and expected proportions of time during which (1) no sentinel was present during observations, and (2) two or more sentinels were present. The majority of social groups spent less time than expected, under the coordination hypothesis, with at least one sentinel, indicating evidence against coordinated vigilance. This was significant for social groups observed in 2015, but not in 2002. Across both years, temporal overlap in sentinel behaviour between two individuals occurred significantly less than expected under the coordination hypothesis. This study contributes to a gap in our knowledge of sentinel behaviour and suggests that Smooth-billed Anis lack organized vigilance, possibly due to low within-group relatedness and group instability.

Group size, but not manipulated whole-clutch egg color, contributes to ovicide in joint-nesting Smooth-billed Anis

Reproductive competition in the form of ovicide is common in some joint-nesting birds, species in which multiple females lay eggs in a single nest. Joint-nesting Smooth-billed Anis (Crotophaga ani) often bury eggs under a new nest floor prior to laying their own eggs. Anis apparently cannot recognize their own eggs, which raises the question of how individuals can minimize their loss of young due to egg burial or consequences of hatching asynchrony. Newly laid eggs are coated with a white layer of vaterite (calcium) while older eggs may be almost entirely blue. Leaving older, bluer eggs in the nest presumably leads to a more competitive nest environment for the female's own young because newer eggs hatch later, producing smaller chicks at risk of getting trampled or bumped out of the nest. We hypothesized that Smooth-billed Anis use egg color as a cue for egg age. We predicted females not yet laying would bury older-looking blue eggs and tested this by removing the vaterite layer from all eggs in selected nests. Contrary to our prediction, altering egg color of whole clutches to make them look bluer, and thus older, did not trigger egg burial. The number of eggs buried increased with increasing female group size, however, consistent with previous work on this species.

Male parental effort predicts reproductive contribution in the joint-nesting, Smooth-billed Ani (Crotophaga ani)

Co-operative breeders provide parental care to non-filial offspring—a behaviour known as ‘alloparental care’. While inclusive fitness benefits are a widely accepted driver of alloparental care in kin-based social groups, such indirect benefits are lost in non-kin societies. Among such societies, theory predicts that the degree of parental and alloparental effort should therefore be proportional to an individual’s genetic contribution to mixed broods—depending upon reproductive options. Using genotyping data across five to 12 microsatellite loci for individuals from 20 social groups (67 adults and 153 nestlings), we assessed whether kinship or proportional reproductive success explained trends in parental and alloparental effort in the Smooth-billed Ani (Crotophaga ani), a joint-nesting cuckoo species. Nocturnal incubation in this species appears to be performed almost exclusively by a single male. We first report significantly higher degrees of relatedness between adults within social groups (\(\bar{r}\) = 0.208, n = 114 dyads), than between social groups (\(\bar{r}\) = 0.120, n = 893 dyads), suggesting that inclusive fitness benefits may in part explain uneven allocation of parental effort. Second, we show that nocturnal incubation status is a significant predictor of reproductive success in males, as nocturnal incubators sire a greater proportion of nestlings in mixed-parentage broods. While patterns of reproductive skew appear high at 80% paternal confidence (\(\bar{B}\) = 0.052, p = 0.061), we report no significant deviation from an egalitarian breeding framework. Our results revealed similar patterns of reproductive allocation to closely related Groove-billed Anis (Crotophaga sulcirostris); however, differences in male reproductive skew and within-group relatedness across crotophagids are highlighted and offer insight into social evolution among anis.

Impact of the functioning of a thermeletry in the bird fauna of the brazilian semiarid

The thermoelectric generate a large amount of pollutants, due to the type of fuel used for electric power generation, damaging in this way, the environment, human health, as well as the surrounding biodiversity. Based on this premise, the objective of this work was to identify the bird species present in the surroundings of a thermoelectric. The study was carried out in the surroundings of the Borborema Energética SA Thermoelectric, in the region of the northeast of Brazil, from January to December 2016, where used the technique of observation by transects and use of mist net to capture images of the birds fauna. In the study area, 29 bird species belonging to 10 orders and 21 families were registered. The order with the most representatives was the Passeriformes, and the families were Tyrannidae, followed by Furnariidae. Of the total number of journeys performed during the daytime of the research, the species with the highest observation frequency was Crotophaga ani. On the abundance, more representatives were the species Crotophaga ani, Coragyps atratus and Thlypopsis sordida. In this context, there was a low abundance and diversity of birds fauna in the region, demonstrating a precarious state of conservation and ecological integrity, which may reflect the impacts of industrialization, installation and operation of the thermoelectric in the area.