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Journal of Ornithology
Number of Followers: 25  Hybrid journal (It can contain Open Access articles)ISSN (Print) 2193-7192 - ISSN (Online) 2193-7206 Published by Springer-Verlag  [2468 journals]
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- Timing of migration and African non-breeding grounds of geolocator-tracked
European Pied Flycatchers: a multi-population assessment-
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Abstract: Abstract Using light-level geolocators, eight European Pied Flycatchers (Ficedula hypoleuca) from two breeding sites in Czechia were tracked. We also gathered all available geolocator tracks on 76 individuals from four European populations and compared the timing of annual cycle events and the African non-breeding sites among all populations. Individuals from both Czech breeding sites had overlapping migration events and non-breeding locations. Four individuals resided in the southwestern edge of Mali, two in Burkina Faso, one in Guinea, and the easternmost one in the Ivory Coast. On average, the birds left the Czech breeding grounds on 8 August and took between one to three stopovers during autumn migration. Birds crossed the Sahara on its western edge on average on 13 September. The mean arrival to the African non-breeding grounds was 47.5 days after departure on 2 October (range 10 September to 10 October). One bird showed intra-tropical movement within West Africa when after a 60-day residency it moved approximately 3° westwards. Estimated locations at the African non-breeding grounds overlapped among tracked birds from five European breeding sites. However, statistically, we could detect longitudinal segregation in two clusters. Birds from the British and Finnish breeding populations shared non-breeding grounds and were located in Africa west of the second cluster of the birds from the Czech and Dutch breeding populations. We show considerable population-specific differences in the timing of annual cycle events. Birds from Dutch breeding sites were the first in all three phases—departure from breeding sites, Sahara crossing and arrival to African non-breeding grounds, followed by the British, Czech, and Finnish birds, respectively. All tracked flycatchers so far fill only the western part of the African non-breeding range. For a complete understanding of the migration pattern in the species, we highlight the need for tracking studies from the eastern part of the range.
PubDate: 2023-10-01
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- Specialist or opportunist—the diet of the European bee-eater (Merops
apiaster)-
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Abstract: Abstract The European Bee-eater (Merops apiaster) is considered a foraging specialist for large flying insects, 80% or more of which are Hymenoptera, mainly bumblebees and other bees, including honeybees. Observations of bee-eaters foraging give rise to doubts about an almost one-sided Hymenoptera diet, as Lepidoptera, Odonata, large Diptera or Heteroptera are also regularly and frequently preyed upon and fed to nestlings and brood mates. In a meta-analysis of 56 studies on the bee-eater's diet, a total of 130,624 prey items from 115 food samples were evaluated. Total of 85 samples (74%) with 83,953 items (72%) came from Southern, Eastern and Central Europe; however, studies from North Africa, Central Russia, Ukraine, Turkmenistan, Uzbekistan, Saudi Arabia and South Africa were also included in the analyses. The collection methods significantly influence the results of the dietary composition. In studies of pellet and stomach contents, the diet was less diverse. It consisted of about 90% Hymenoptera and Coleoptera overall, whilst other arthropods were rarely detected. Studies based on direct observation or photo documentation showed that the diet was more diverse, and Hymenoptera were not always the most abundant, but could also include Odonata, Lepidoptera, Tabanidae, Syrphidae, Saltatoria, Heteroptera or Hemiptera in significant amounts. The proportion of Hymenoptera in these studies was 49%, about a third (20%pts – 30%pts) lower than in the pellet and stomach content studies, and the proportion of Coleoptera (13%) about a quarter lower. We assume that bee-eaters completely digest weakly sclerotised prey and that these are, therefore, not detected in pellets and stomachs, or only in low numbers. This means that 81% of published studies on the bee-eater's diet are based on methods that lead to quantitatively and qualitatively unrepresentative results and thus do not provide precise results of diet compositions. Observational and photographic methods have only been used to study the nestling diet. Therefore, a reliable statement about what adult bee-eaters eat themselves and how the diet is composed quantitatively is currently not possible. The diet of adult and juvenile birds could only be compared based on the poorly representative pellet and stomach content analyses. This analysis is limited to the abundance of Hymenoptera and Coleoptera, which are well detectable in pellets and stomachs. Hymenoptera were significantly more abundant in the nestling diet, whilst coleopterans were more abundant in the adult diet. The diet also varied regionally. Bumblebees, because of their sluggish flight and because they are already active at relatively low ambient temperatures, are important food animals in climatically less optimal and oceanic areas at the northern edge of the range. In other regions, Hymenoptera occur less frequently and less regularly, whilst Coleoptera, Odonata, Lepidoptera, large Diptera, Saltatoria, Isoptera or Hemiptera may occur locally in significant numbers as prey. The extent to which diet varies seasonally could not be clearly proven. Only one of five studies shows weakly significant changes in diet composition over the breeding season. This study is based on direct observation of prey fed to nestlings, whilst the other studies examined prey remains in pellets. Although the pellet studies also showed different food compositions over the course of the brood, trends between studies were inconsistent and not significant overall. We hypothesise that local influences (weather, habitats) affected diet composition. Further analysis is needed to determine whether food supply or demand changes during the breeding season. In addition to analysing the food composition, also the food supply must be surveyed, which has rarely been done so far. The opportunistic use of food resources can support the successful colonisation of breeding areas and is probably an important factor in the current successful expansion of the European bee-eater.
PubDate: 2023-10-01
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- Guess who' Evaluating individual acoustic monitoring for males and females
of the Tawny Pipit, a migratory passerine bird with a simple song-
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Abstract: Abstract Individual acoustic monitoring (IAM), based on the analysis of vocal cues, is particularly suitable for the identification and tracking of birds with temporally stable song or call characteristics. Unlike mark-recapture methods, IAM does not require the physical manipulation of individuals, which can have long-lasting behavioural effects. So far, IAM has usually focused on males, as singing females tend to be overlooked in temperate zones. Here, we evaluated the suitability of IAM for both sexes in an isolated population of the Tawny Pipit (Anthus campestris, Motacillidae), a migratory Palearctic species critically endangered in Central Europe, for which female singing has been occasionally documented. We confirmed that songs of all 101 studied individuals, both males and females, were individually distinct. Most individuals used only a single song type in their repertoires, with only three males using two. Of 45 ringed males (that could be unambiguously recognized visually), only two changed their song structure to some extent, either within or between seasons. Multiple individuals often sang structurally similar song types, which nevertheless consistently differed in minor characteristics; such differences were detectable by visual inspection and also affected quantitative analyses of song similarity. Songs sung by females did not have any apparent sex-specific characteristics. Unlike previously suggested, females did not adapt their vocalization to their breeding partner, and we presume their song is also temporally stable. Our findings support IAM as a reliable approach for studying the behaviour and ecology of this passerine species with a small repertoire and simple songs.
PubDate: 2023-10-01
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- Incubation behaviour of the Common Ringed Plover Charadrius hiaticula at
different latitudes-
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Abstract: Abstract In biparental Charadriinae plovers, male and female incubation duties often resemble daily routines, with males typically incubating at night and females incubating during the day. By analysing incubation behaviour in three Arctic populations of Common Ringed Plover Charadrius hiaticula, we show that these diel routines are lost in the 24-h sunlight of the Arctic. In contrast, a non-Arctic population in East Scotland exhibited significant daily routines, with males dominating incubation during the late afternoon and night, and females dominating incubation during the early morning and midday hours. These patterns suggest that clear light/dark cycles are necessary for daily incubation routines to form in the Common Ringed Plover, although further research is needed to understand the specific drivers of this behaviour.
PubDate: 2023-10-01
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- Brood survival in the Red-backed Shrike Lanius collurio in eastern Poland
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Abstract: Abstract Brood survival as an expression of breeding success is a component of bird fitness and the principal parameter underlying bird population dynamics. The main factor limiting brood survival is predation pressure, and birds have developed anti-predator strategies by selecting safer places for building nests and breeding. Here, we examined whether nest location affected the level of predation pressure. To do so, we analyzed brood survival in a Red-backed Shrike (RBS) Lanius collurio population breeding in the low-intensive agricultural landscape of eastern Poland. The mean survival probability for the whole nesting period was 0.540 and was higher for the incubation period (0.787) than for the nestling period (0.696). Cox’s proportional hazard model did not show any significant traits describing the location of the nesting shrub or the nest’s position in the shrub that could have affected RBS brood survival. We consider the composition of the local predator community to influence brood survival more than the location of a nest in the bush. The Eurasian Magpie Pica pica is mainly responsible for RBS brood predation. Red-backed Shrikes do not defend their broods against Magpies using acoustic signals and direct contact. Since Magpies search the bushes thoroughly, the shrikes’ nest concealment strategies are ineffective in the face of this predator.
PubDate: 2023-10-01
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- Dynamics of stress-induced changes of leukocyte profile in Great Tits:
testing effect of age-
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Abstract: Abstract Leukocyte profile parameters are often used as indicators of individual condition, long-term stress and immune system state in birds and other animals. Therefore, it is important to obtain baseline values of leukocyte profile parameters unaffected by stressful stimuli, including capture and handling. However, information about the timing of stress-induced changes in the leukocyte profile has been obtained only for a limited number of species, and there is little data on how various factors (e.g. environmental stimuli, life-history stage or age) affect these changes. In our study, we examined the dynamics of changes in leukocyte profiles following capture in male Great Tits (Parus major), and tested the effect of age on these dynamics. The numbers of lymphocytes, heterophils and heterophil to lymphocyte ratio (HL ratio) began to change between 30 and 60 min after capture, while significant changes in the total white blood cell (WBC) counts appeared later, 60–90 min after capture. Eosinophil numbers were stable within 90 min of capture. We did not observe an effect of age on the timing of stress-induced changes in the leukocyte profile. Overall, our results corroborate previous data obtained from Great Tits but disagree with data for some other avian species. We assume that the dynamics of leukocyte profile changes are likely to be species-specific. We conclude that to obtain baseline values of leukocyte profile parameters, blood samples should be preferably taken within 30 min after capture.
PubDate: 2023-10-01
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- Bursts of white noise trigger song in domestic Canaries
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Abstract: Abstract Acoustic communication is fundamentally constrained by noise. In birds, the masking of mating signals (songs) may reduce fitness and, hence, they have evolved various mechanisms to maintain communication in noise. One of these tactics is the adjustment of song timing to avoid overlap with masking sounds, but previous studies yielded contrasting results regarding the occurrence and magnitude of this behavioural plasticity. Here, we investigated how temporal noise avoidance varies with noise intensity. We exposed singing Canaries (Serinus canaria) to playbacks of masking noise of varying amplitude [60–80 dB(A) SPL]. Contrary to our prediction, the birds did not shift song onsets to the silent intervals between noise bursts at high noise amplitudes, nor did they increase singing outside the playback period. Rather, we found that noise generally triggered the onset of song: the Canaries preferentially sang during the noise bursts independent of the noise amplitude. This behaviour is somewhat paradox because it leads to the most unfavourable signal-to-noise ratios. Our results, together with findings from the current literature, indicate marked species differences in the noise-induced song plasticity of birds. Therefore, we suggest a more comprehensive conception of noise that incorporates both supressing and stimulating effects.
PubDate: 2023-10-01
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- Vulture perceptions in a socio-ecological system: a case study of three
protected areas in KwaZulu-Natal, South Africa-
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Abstract: Abstract Vultures are presently the most threatened raptor guild in the world. Threats to vultures are numerous and mainly anthropogenic. Understanding human communities' relationship with threatened species can guide and strengthen conservation initiatives. We assessed the awareness, benefits, beliefs, threats, and conservation perspectives of people surrounding protected areas accommodating the few remaining vulture strongholds in KwaZulu-Natal, South Africa. We conducted a total of 450 semi-structured interviews and seven focus group discussions. Respondents demonstrated a strong awareness of vultures and reportedly derived benefits from having these avian scavengers in their localities. The most cited benefit (65%) was carrion removal. A predominant belief amongst local people was that vultures are potent in traditional medicine (66%); this was regarded by the majority of respondents (79%) as the main driver for the illegal killing of vultures. Most participants (84%) viewed vulture populations to have declined. Overall, local people demonstrated complex but predominantly positive perceptions towards vultures. Mounting evidence of the use of vultures in traditional medicine compels urgent action. We recommend co-learning-based engagements between resource users and conservation scientists.
PubDate: 2023-10-01
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- Stopover-site feather isotopes uncover African non-breeding grounds of
migratory passerines-
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Abstract: Abstract The survival of migratory passerines depends considerably on conditions experienced on their non-breeding grounds. However, these critical non-breeding sites are generally poorly known, especially for species and populations using the eastern Afro-Palearctic flyway. To fill this gap, we measured hydrogen stable isotopes in winter-grown feathers (δ2Hf) of five long-distance migratory passerines (Eurasian Blackcap, Eastern Olivaceous Warbler, Eurasian Reed Warbler, Olive-tree Warbler, and Barred Warbler) collected during spring migration at a stopover site in Israel, a major migratory bottleneck in the Afro-Palearctic Flyway. We determined non-breeding origins of these species, for the entire migrating population and for early- and late-arriving individuals separately. We used a probabilistic model based on feather isotopes and isotopic distribution of precipitation δ2H (δ2Hp) in Africa, as well as range maps derived from species distribution models and expert opinion. While our results suggested that Reed Warbler and Olive-tree Warbler occupy most of their known range during the non-breeding season, Blackcaps migrating through Jerusalem, Israel, likely spent the non-breeding season specifically in Ethiopia and near areas, and Eastern Olivaceous Warbler concentrated in two regions in eastern tropical and central Africa. Barred Warblers’ non-breeding grounds were estimated in Kenya, but the species distribution model approach suggested additional regions. Our results further suggested that early- and late-arriving Reed Warblers spent the non-breeding season in separate areas, whereas early- and late-arriving Blackcaps migrated to the same area. Given the rapid decline in many migratory species, our results are important for a more accurate evaluation of the conditions experienced during the non-breeding season and our study is a template for refining migratory connectivity estimates for species using this important flyway.
PubDate: 2023-10-01
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- How common is hybridization in birds'
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Abstract: Abstract Hybridization—the interbreeding of different species—plays an integral role in the evolution of numerous bird species. However, it remains unclear how widespread this phenomenon is within and across different bird groups. Estimating the incidence of hybridization in different bird lineages can inform comparative analyses to uncover the evolutionary and ecological forces that promote or prevent the formation of hybrids. Estimates on a species level have varied from about 10% to almost 20% of hybridizing bird species. The variation among the latest estimates largely depends on the choice of global species checklists with differing decisions on the taxonomic status of certain (sub)species. However, the hybrid records in these estimates have generally been taken at face value. Detailed assessments of these records revealed that some cases are unreliable or incorrect. Removing of these faulty records and discovery of novel hybrids will result in a fluctuating percentage of hybridizing species that can best be captured in a living document (e.g., a regularly updated website or checklist). Estimating hybridization on an individual level is more challenging. A first attempt, using citizen science data from the eBird project, reported 0.064% hybrid individuals in the United States. This percentage is probably an underestimate due to underreporting of hybrids by birdwatchers and remains to be finetuned by considering other confounding factors, such as spatial and temporal variation in hybridization dynamics. Future efforts in estimating avian hybridization will need to rely on a combination of data sources and techniques, such as genetics, museum specimens, and citizen science.
PubDate: 2023-10-01
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- Amur Honeysuckle (Lonicera maackii) increases abundance and diversity of
shrub-dwelling arthropods and birds in forest edge habitat-
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Abstract: Abstract Amur Honeysuckle (Lonicera maackii) is an invasive species predominantly found throughout the eastern United States. While prior research has found that invasive honeysuckles negatively impact plant communities, there is conflicting evidence on whether honeysuckle has positive or negative impacts at higher trophic levels. Birds and arthropods living in invaded habitats may potentially be affected by this plant, with changes to the arthropod community leading to changes in the avian community, as they serve as a food source to many bird species during the breeding season. We investigated this question by comparing bird and arthropod abundance, richness, diversity, and species composition between invaded and uninvaded areas in forest edge habitat. Birds were counted at 20 sites and arthropods were collected from shrubs at each site using the beat sheet method. Differences between invaded and native sites were compared using Linear Mixed Models and Nonmetric Multidimensional Scaling. We found that both birds and arthropods were more abundant and diverse in honeysuckle-invaded habitat than uninvaded areas. While morphospecies composition of arthropods was similar between honeysuckles and native shrubs, avian species composition was significantly different between habitat types. Birds commonly found in more urbanized areas were associated with honeysuckle invasion, while more sensitive species were associated with sites free of honeysuckle. These findings suggest the honeysuckle is contributing to biotic homogenization and should be considered for avian management purposes. However, additional research into diet and foraging behavior is necessary to better understand the patterns we observed.
PubDate: 2023-10-01
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- Dynamics in spatial use by Ospreys (Pandion haliaetus) during the breeding
season revealed by GPS tracking-
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Abstract: Abstract The migratory behaviour of Ospreys (Pandion haliaetus) has been well studied using satellite telemetry, but studies on their behaviour in the breeding area are scarce. We caught and fitted 17 adult Ospreys with solar-powered GPS-enhanced satellite transmitters in northeast Germany and tracked them for up to 7 years. There was a high variation in home range size depending on sex, nesting site and breeding success. The home ranges of successfully breeding males (median 33.4 km2, 95% kernel density estimations) were significantly larger than those of females (median 4.6 km2) and varied in extent and shape between individuals. Some females made long excursions and sometimes spent the night at great distances to their nests after the juveniles had fledged but they also returned to the nesting area before they left for migration. The males’ home range areas were consistent during the breeding period. The proportion of water surfaces on the home range areas of males ranged between 9.6 and 29%. The overnight roosts were found in distances up to 7.83 km (median 980 m) for successfully breeding males and up to 105 km (median 568 m) for successfully breeding females. The correlation between overnight roost-nest distance and the corresponding home range area was significant for females but not for males. The overlap in the home ranges of individual males that occupied the same nests in different years varied between 37.3 and 54.7% of the mutual home ranges. Males partly included the same waterbodies in their home ranges, but they also visited different lakes. In the incubation and nestling phases, females are closely bound to the nest, whereas their mates can range over vast areas.
PubDate: 2023-10-01
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- Narrow-beaked trogons from the early Eocene London Clay of
Walton-on-the-Naze (Essex, UK)-
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Abstract: Abstract We describe multiple partial skeletons of a new trogon species from the early Eocene London Clay of Walton-on-the-Naze (Essex, UK), which are among the oldest fossils of the Trogoniformes. Eotrogon stenorhynchus, gen. et sp. nov. has a much narrower and more gracile beak than extant trogons, which denotes different ecological attributes of the fossil species. Eotrogon stenorhynchus already had the heterodactyl foot characterising extant trogons, even though the trochlea for the second toe is smaller than in crown group Trogoniformes. Differences to extant trogons in the wing and pectoral girdle elements suggest that E. stenorhynchus was less adapted to short-term hovering, which may indicate different foraging techniques. We also report a partial tarsometatarsus from the early Miocene of France that is likely to belong to Paratrogon gallicus, a species previously only known from humeri. P. gallicus is the earliest modern-type trogon, and we show that the newly identified tarsometatarsus does not support the proposed referral of this species to the African taxon Apaloderma. We identify skeletal features that suggest a sister group relationship between Apaloderma and all other crown group Trogoniformes, but the exact affinities of Paratrogon remain poorly resolved. (http://zoobank.org/urn:lsid:zoobank.org:pub:73B64B84-11C2-4D50-8540-099CF86B6CA1).
PubDate: 2023-10-01
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- The ethnomedicinal use of vultures by traditional health practitioners in
KwaZulu-Natal, South Africa-
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Abstract: Abstract African traditional medicine contributes to greater healthcare coverage by providing primary healthcare to rural dwellers, who often have limited access to modern medical services. However, the prevalence of traditional medicine use has been reported to put pressure on biological resources upon which it relies. Indigenous people have identified many wild animals as possessing curative properties. The use of animals and their body parts as ingredients in traditional medicine is often poorly regulated and therefore represents a major challenge for biodiversity conservation. We investigated traditional health practitioners’ ethnomedicinal use of vultures in KwaZulu-Natal, South Africa. In-depth interviews were conducted with 26 traditional health practitioners from two district municipalities. Data collected were analysed through qualitative and quantitative methodologies. We documented seven parts of the vulture that traditional health practitioners used in KwaZulu-Natal. When the Use Value (UV) index was calculated for each part, the head obtained the highest (0.92). Consensus on parts and their uses was generally low across the study group. Of the 21 uses reported for vulture parts, 71% were spiritual-based. The participants were aware of the hunting of vultures through the use of poison but demonstrated different views about the risks associated with using such material. Overall, our findings confirm the increasing use of African vultures in traditional medicine. Raising awareness and upscaling the active involvement of traditional health practitioners in natural resource management may benefit vulture conservation and that of other species commonly used in belief-based practices.
PubDate: 2023-10-01
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- Irruptions of Bohemian Waxwings in relation to population density and food
availability-
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Abstract: Abstract Bird irruptions are thought to be triggered by a combination of lack of food in the regular distribution range and high population density (push factors). Recent studies have also suggested that irruptions may be drawn towards areas with high food availability (pull factor). The Bohemian Waxwing (Bombycilla garrulus) is an irruptive species with large annual variation in the numbers reaching southern areas during winter. I used long-term (up to 41 years) data on annual number of waxwings observed during breeding in Finland and Sweden, during winter in Norway, Sweden, Denmark, UK and Poland, and data on their main winter food, Rowanberries (Sorbus aucuparia; masting occurs at 2–3 year intervals) from Norway (southern areas) and Finland (overlapping with northern breeding areas) to test the push and pull hypotheses. Winter numbers fluctuated in synchrony over large parts of northern Europe. In years with low food availability in Finland waxwings arrived to southern areas early, and early arrival to southern areas was linked to larger winter numbers in some countries. However, controlling for arrival time to southern areas, numbers were larger when there were more rowanberries in Finland. Thus, irruptions generally occurred with high rowanberry abundance, but sometimes occurred with the combination of low rowanberry abundance and early arrival. There was mixed evidence that irruptions were linked to high breeding population density. There was no support that irruptions were drawn towards high rowanberry abundance in southern areas. In conclusion, waxwing irruptions had complex relationships with food availability, but most irruptions occurred in years with high rowanberry abundance in autumn in northern areas. This is opposite to expectations from the current view that irruptions are triggered by lack of food, but irruptions departing late may still have been triggered by abundant food finally becoming depleted late in winter.
PubDate: 2023-10-01
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- The demography of the White-headed Petrel at Mayes Island, Kerguelen
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Abstract: Abstract The demography and factors affecting the population dynamics of gadfly petrels (Pterodroma spp.) remain poorly known, although they constitute the most diverse genus of Procellariiformes and many species are threaten. Using a long-term individual monitoring dataset over 35 years, this study provides estimates of state-specific demographic parameters of the White-headed Petrel (Pterodroma lessonii) from Mayes Island, Kerguelen archipelago, and tests for the effects of environmental factors. Age at first breeding was 8.7 ± 2.6 years and apparent adult annual survival was 0.941 ± 0.058. Annual breeding probability was 0.356 ± 0.036 for successful breeders and 0.988 ± 0.054 for individuals that took a sabbatical year after a successful breeding event. Successful breeders that bred during two consecutive years had a lower breeding success (0.574 ± 0.048) that individuals that bred after a sabbatical year (0.655 ± 0.036). The realized population growth rate (1.073 ± 0.011) suggested that the population is increasing. There was a slight evidence for a positive effect of the Southern Annular Mode on the breeding probability of successful breeders, but no effect of sea surface temperature, chlorophyll a or wind was detected on demographic parameters. This study revealed that White-headed Petrels had a particularly high adult survival coherent with a quasi-biennial strategy and late age at first breeding. According to life history theory, populations of White-headed Petrel are thus likely to be very sensitive to small variations in adult survival, and anthropogenic factors causing additive mortality such as introduced predators will constitute serious threats for this species.
PubDate: 2023-10-01
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- Male but not female Kentish plovers Charadrius alexandrinus modulate
foraging behaviour according to tide during incubation-
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Abstract: Abstract During breeding, birds have to find a balance between reproductive tasks and the need to recover their energy. Foraging movements are constrained in time and space by brood guarding and chick-rearing activities at the nesting site. Foraging behaviour differs among species according to their ecology but it can change, even markedly, among individuals of the same species according to intrinsic and extrinsic factors, such as sex, habitat, intra and inter-specific interactions. By means of individual GPS tracking, we assessed foraging behaviour of egg-incubating Kentish plovers breeding along a sandy beach bordering the Venice Lagoon. Both sexes foraged on the beach were they bred, but also in the lagoon, travelling up to 16 km far from the nest. In both habitats, individuals foraged in areas that were significantly separated from those used by other tagged conspecifics, likely lowering intra-specific competition. Males foraged mainly at daytime, in the lagoon at low tide and on the beach at high tide. Differently, females foraged mainly at night and in the lagoon, and less often on the beach exclusively during daytime, regardless of tide height. The avoidance of nocturnal foraging on the beach by females might be explained as antipredatory response to the presence of owls breeding in a pinewood adjacent the beach or to a possible diet specialization on prey that are available in the lagoon at night, irrespective to tide conditions. Overall, this study revealed an unexpected sexual difference in foraging behaviour of Kentish plover, with sexes likely facing different environmental pressures according to diurnal and nocturnal foraging.
PubDate: 2023-10-01
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- Leg coloration is associated with habitat type and social environment in
swallows and martins-
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Abstract: Abstract Plumage ornaments, such as colourful feathers and deeply forked tails, are classic examples of sexually selected ornaments, and are shown to be related to ecological factors on an evolutionary time scale. In contrast, although colourful bare skin could also be a visual ornament, few studies have examined the evolutionary relationship between colourful bare skin and ecological factors and its interrelationship with plumage ornaments. Using a phylogenetic comparative approach, we studied leg (and foot) coloration in relation to ecological factors, particularly in habitat type (montane or not), and to well-known sexually selected traits, deeply forked tails and reddish plumage coloration, in the subfamily Hirundininae. We showed that mountain species had redder legs than others. Although we also found that social breeders had redder legs than others, the relationship between habitat type and leg coloration remained significant even after controlling for this relationship. In contrast, tail fork depth and reddish plumage coloration were not significantly related to habitat type. Because leg coloration and these plumage ornaments were not significantly interrelated, they likely evolved partially independently. We also found that mountain species had longer nestling periods than others, indicating higher parental investment in montane area in these monogamous birds. Because bare skin coloration is a dynamic honest signal of the current body condition and parental care ability, birds might utilise this information for successful breeding, particularly in environments where extensive parental care is required.
PubDate: 2023-10-01
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- Cues to individuality in Greylag Goose faces: algorithmic discrimination
and behavioral field tests-
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Abstract: Abstract Cues to individuality, and the corresponding capacity for individual-level discrimination, can allow individually specific investment by conspecifics into offspring, partners, neighbors or competitors. Here we investigated possible cues to individuality via faces in an ancient avian lineage, the Greylag Goose (Anser anser). Konrad Lorenz could famously name each Greylag Goose in ‘his’ flock from a photograph. Confirming this anecdotal observation, we developed facial recognition software that can reliably (~ 97% accuracy) assign a goose face to a goose ID within a database, using bill morphology normalized during photo preparation. To explore conspecific detection of individuality cues, we erected life-size photos of geese and measured subjects’ responses to photos of themselves (unfamiliar goose), their partner, and another flock mate. Geese displayed significantly greater affiliative response to photos of their partners, providing evidence that geese can use two-dimensional images as cues to determine social category (partner/non-partner) and/or individual-level recognition. Our methods provide novel approaches to automatically detect and monitor geese and to test avian cognition. Our approach may also create new opportunities for species monitoring approaches more generally using photographic images and citizen-science engagement.
PubDate: 2023-09-27
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- The vocal repertoire and the daily calling activity of the Yellow-breasted
Barbet (Trachyphonus margaritatus)-
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Abstract: Abstract The Yellow-breasted Barbet (Trachyphonus margaritatus) is a group-living and chorusing bird species. However, its vocal repertoire remains poorly described. In this study, we measured the acoustic features of four distinct vocalisations as well as the daily calling activity of barbets at 11 roosting cavity sites. We found that bird’s peak of calling activity is early in the morning and at the end of the day. The cohesion calls and group vocal displays were the most common vocalisations. Moreover, cohesion calls were often used before the start of a group vocal displays which suggests a function in the intra-group cohesiveness.
PubDate: 2023-09-26
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