Avian Taxa Research Articles

Preliminary evidence that eye appearance in parrots (Psittaciformes) co-varies with latitude and altitude

External eye appearance in avian taxa has been proposed to be driven by social and ecological functions. Recent research in primates suggests, instead, that, photoprotective functions are important drivers of external eye appearance. Using similar methods, we examined the variation in external eye appearance of 132 parrot species (Psittaciformes) in relation to their ecology and sociality. Breeding systems, flock size and sexual dimorphism, as well as species’ latitude and maximum living altitude, and estimated UV-B incidence in species’ ranges were used to explore the contribution of social and ecological factors in driving external eye appearance. We measured the hue and brightness of visible parts of the eye and the difference in measurements of brightness between adjacent parts of the eye. We found no link between social variables and our measurements. We did, however, find a negative association between the brightness of the inner part of the iris and latitude and altitude. Darker inner irises were more prevalent farther away from the equator and for those species living at higher altitudes. We found no link between UV-B and brightness measurements of the iris, or tissue surrounding the eye. We speculate that these results are consistent with an adaptation for visual functions. While preliminary, these results suggest that external eye appearance in parrots is influenced by ecological, but not social factors.

Effects of body mass and taxonomic order on the masses of functionally classified groups of the jaw musculature in birds

Abstract There is increasing interest from evolutionary biologists in the evolution of avian bill shape, how the bill is used during feeding and, in particular, the bite forces the bill can deliver. Bite force exhibits isometry with the total mass of the jaw musculature, but there is variation in the functional categories of the jaw muscles in different avian taxa. Qualitative descriptions of the jaw musculature do not allow analysis of the relative contributions that adductor or retractor muscles play in generating a bite force. This study is a meta-analysis of published data for body mass and the mass of the jaw musculature in 66 bird species from 10 orders. The masses of the different muscles contributing to adduction and retraction in closing the jaw, and to depression and protraction in opening the jaw, were summed and allometric relationships explored before investigating the effects of taxonomic order on these relationships. The categories of muscles, and the masses of each category of jaw musculature varied among avian orders. Some species, such as the flightless ratites, had relatively small jaw muscle mass but parrots had an additional adductor muscle. Phylogenetically controlled relationships between body mass and the mass of each muscle category irrespective of taxonomic order were isometric. However, analysis of covariance revealed significant interactions between body mass and taxonomic order. Most orders had low values for body-mass-specific muscle masses in the jaw with the notable exceptions of the Passeriformes (songbirds) and Psittaciformes (parrots). The values of these orders were 3–4 times greater, although the relative amounts of muscles contributing to adduction and retraction were similar in Psittaciformes, but adduction was markedly higher in Passeriformes. The results of these analyses highlight the lack of species-specific data for most birds, which is adversely impacting our understanding of the anatomical features that are determining the functional properties of the bill during feeding.

Individual foraging site fidelity persists within and across stopover seasons in a migratory shorebird, Numenius phaeopus (Whimbrel)

Abstract Site fidelity—returning repeatedly to the same site—can help many migratory species reduce uncertainty in their environment, especially when migratory stopover periods leave little time to explore and evaluate new habitat. Avian taxa, though, have shown wide variation in their levels of site fidelity during migration, and few studies have been able to examine individual-level fidelity at fine spatiotemporal scales. We used a high-resolution GPS tracking dataset of Numenius phaeopus (Whimbrel), a long-distance migratory shorebird, to assess levels of fidelity to specific foraging and roosting sites during migration, both within and between stopover seasons. We found that individuals are almost exclusively faithful to one shared roost site at night, but disperse to individual foraging territories during the day that overlap with each other by <20%. Individuals remain faithful to these distinct territories over time, on average shifting the center of their daily home ranges by <1.5 km within a single season, and overlapping with their previous season’s home range by 70% when they return during subsequent stopovers. Our findings reveal for the first time that a shorebird species exhibits fine-scale, individual foraging site fidelity during and between migratory stopovers—an important insight to inform effective conservation and management action.

Diel and Vertical Niche Differentiation of Frugivore Communities Feeding on Ficus nota (Blanco) Merr.

Ficus species are keystone species in tropical ecosystems for frugivores. Nonetheless, ecological aspects of fig frugivory such as niche differentiation are understudied, leading to huge gaps in the knowledge of fig-frugivore interactions. We used camera traps to monitor the vertical and diel activity of frugivores feeding on a Ficus nota tree in Cavite, the Philippines for 70 d to determine vertebrate species feeding on Ficus nota and their niche differentiation mechanisms. We observed several mammalian taxa (pteropodid fruit bats, Rattus sp. and Paradoxurus philippinensis) and several avian taxa (Hypsipetes philippinus, Pycnonotus goiavier, Lanius cristatus, and Centropus viridis). All of the detected species were observed to be perching on, inspecting, or eating fruits. However, based on existing literature, two of the four bird species detected (L. cristatus and C. viridis) are known to be carnivorous. Diel niche differentiation was evident from the diurnal and nocturnal activity patterns of birds and mammals, respectively. We also detected temporal activity differences between pteropodids and P. philippinensis, hence suggesting temporal niche differentiation. Pteropodids were also more active in the terrestrial stratum, whereas non-pteropodids were more active in the arboreal stratum, hence suggesting vertical niche differentiation. Diel niche differentiation may be attributed to differences in food acquisition adaptations, whereas vertical niche differentiation may be attributed to differences in tree morphology between strata and in frugivore adaptations for mobility. These results show that Ficus nota acts as a food source and habitat for frugivores and non-frugivores and that interspecific interactions are mediated by niche differentiation. Our findings underscore the potential of Ficus nota as a species in restoration efforts to support seed-dispersing frugivores and other wildlife species, as well as the utility of camera trapping to survey frugivores in understudied habitats.

The impact of diet on sperm length in the long‐tailed finch (Poephila acuticauda)

Sperm traits are important in determining fertilisation success and are metabolically expensive to produce. There is little known about how energy acquisition and allocation affect sperm traits in avian taxa. This study assesses the impact of experimentally manipulated diet on long‐tailed finch sperm by comparing the length of sperm components (head, midpiece, flagellum and total sperm) between the treatment groups (homogenous diet and diverse diet) and across time points (before and after the experiment). Diet homogeneity was manipulated as this may impact diet quality in a species that is usually fed a diversity of seed species to thrive in captivity. Our results showed no impact of diet on the length of different sperm components. These results contrast with findings of a similar recent study of the zebra finch which found a significant level of diet‐affected plasticity in midpiece length. For both diet treatment groups in this study there was a slight but significant increase in head, flagellum and total sperm length over the treatment period. Despite this, all sperm components were highly repeatable, consistent with the finding from observational studies in passerine birds. The efficacy of our dietary manipulation was confirmed by a significant reduction in the saturation of bill colour in the long‐tailed finches as a result of the homogenous diet, and a difference in body mass across the treatment groups.

Divorce rate in monogamous birds increases with male promiscuity and migration distance.

Socially monogamous birds may break up their partnership by a so-called 'divorce' behaviour. Divorce rates vary immensely across avian taxa that have a predominantly monogamous social mating system. Although various factors associated with divorce have been tested, broad-scale drivers of divorce rate remain contentious. Moreover, the influence of sexual roles in divorce still needs further investigation because of the conflicting interests of males and females over mating and fertilization. Here, we applied phylogenetic comparative methods to analyse one of the largest datasets ever compiled that included divorce rates from published studies of 186 avian species from 25 orders and 61 families. We tested correlations between divorce rate and a group of factors: 'promiscuity' of both sexes (propensity to polygamy), migration distance and adult mortality. Our results showed that only male promiscuity, but not female promiscuity, had a positive relationship with divorce rate. Furthermore, migration distance was positively correlated with divorce rate, whereas adult mortality rate showed no direct relationship with divorce rate. These findings indicated that divorce might not be a simple adaptive (by sexual selection) or non-adaptive strategy (by accidental loss of a partner) in birds but it could be a mixed response to sexual conflict and stress from the ambient environment.

The relationships of breeding stage to daytime singing behaviour and song perch height in Bermuda white‐eyed vireos Vireo griseus bermudianus

Bird song is crucial for attracting mates and defending territories, but different types of song or different singing behaviours may be involved in acquiring or maintaining each resource. Furthermore, male songbirds may adjust when and where they sing throughout the breeding season, depending on their breeding stage. However, such relationships remain untested in several avian taxa. Here, we studied male Bermuda white‐eyed vireos Vireo griseus bermudianus, a passerine with two distinct song types (discrete and rambling), to test the mate attraction and territory defence hypotheses. We compare song production and song perch height among different stages of the breeding season and during the non‐breeding season. We show that male vireos produce both song types during the breeding and non‐breeding seasons, suggesting dual roles in mate choice and territorial defence. Song production did not differ significantly between the breeding and non‐breeding seasons, but, within the breeding season, males without nesting duties sang significantly more songs than males with nesting duties. Song perch height was higher during the breeding season versus non‐breeding season, among males without nesting duties compared to males with nesting duties, and when males produced discrete versus rambling songs. Our findings suggest that male vireos increase their conspicuousness to prospecting females by increasing song production and song perch height, and that they sing during the breeding and non‐breeding seasons to defend year‐round territories. Collectively, our study supports the mate attraction and territory defence hypotheses of bird song.

Interactive effects of rising temperatures and urbanisation on birds across different climate zones: A mechanistic perspective.

Climate change and urbanisation are among the most pervasive and rapidly growing threats to biodiversity worldwide. However, their impacts are usually considered in isolation, and interactions are rarely examined. Predicting species' responses to the combined effects of climate change and urbanisation, therefore, represents a pressing challenge in global change biology. Birds are important model taxa for exploring the impacts of both climate change and urbanisation, and their behaviour and physiology have been well studied in urban and non-urban systems. This understanding should allow interactive effects of rising temperatures and urbanisation to be inferred, yet considerations of these interactions are almost entirely lacking from empirical research. Here, we synthesise our current understanding of the potential mechanisms that could affect how species respond to the combined effects of rising temperatures and urbanisation, with a focus on avian taxa. We discuss potential interactive effects to motivate future in-depth research on this critically important, yet overlooked, aspect of global change biology. Increased temperatures are a pronounced consequence of both urbanisation (through the urban heat island effect) and climate change. The biological impact of this warming in urban and non-urban systems will likely differ in magnitude and direction when interacting with other factors that typically vary between these habitats, such as resource availability (e.g. water, food and microsites) and pollution levels. Furthermore, the nature of such interactions may differ for cities situated in different climate types, for example, tropical, arid, temperate, continental and polar. Within this article, we highlight the potential for interactive effects of climate and urban drivers on the mechanistic responses of birds, identify knowledge gaps and propose promising future research avenues. A deeper understanding of the behavioural and physiological mechanisms mediating species' responses to urbanisation and rising temperatures will provide novel insights into ecology and evolution under global change and may help better predict future population responses.

Accelerating declines of North America’s shorebirds signal the need for urgent conservation action

Abstract Shorebirds are declining to a greater extent than many other avian taxa around the world. In North America, shorebirds, along with aerial insectivores and grassland birds, have some of the highest proportions of declining species of any group. Here, we apply a new hierarchical Bayesian model to analyze shorebird migration monitoring data from across North America, from 1980 to 2019, and present the most recent available estimates of trends for 28 species. Point estimates for survey-wide trends in abundance were negative for 26 of 28 species (93%). Despite challenges with low precision associated with migration count data, trends for 19 species had 95% credible intervals that were entirely negative. More than half of the species were estimated to have lost >50% of their abundance. Furthermore, estimated rates of decline have accelerated during the last three generations for most species. Point estimates of trend were more negative for 18 species (64%) during the most recent three-generation period in comparison to the previous three-generation period. Many species now exceed international criteria for threatened species listing. The analytic approach used here allows us to model regional variation in trends, although survey coverage and strength of inference were greatest in the eastern portions of North America (east of 100°W). We found the greatest declines at staging sites along the Atlantic Coast from North Carolina to Nova Scotia, and lesser declines along the Gulf Coast and in the midcontinental United States. The declines in shorebird populations reported here are worrisome and signal the urgent need for conservation action. In addition, it would be beneficial to validate these results through the collection and analysis of complementary data, and to initiate demographic studies throughout the annual cycle to determine where and when declines are most likely to originate. This improved information will allow for the development of more targeted efforts to reverse declines through conservation action.

Range shift and loss of genetic diversity under climate change in the red-backed fairywren (Malurus melanocephalus), an Australian endemic bird species

AbstractClimatic variability is the most important force influencing the distribution dynamics of common and widespread species, with significant effects on their current biogeographical patterns. In this study, phylogeography was integrated with ecological niche modelling to understand the range dynamics of an Australian bird species, the red-backed fairywren (Malurus melanocephalus), under various climate change scenarios. Specifically, an ecological niche modelling approach with Bayesian-based phylogeographical analysis was used to develop robust inferences regarding the demographic history of the species. The predictions of the model were mostly consistent with the present distribution of the species. However, under the Last Interglacial bioclimatic conditions, the model predicted a significantly narrower distribution than today, indicating the existence of allopatric refugia. Predictions for the Last Glacial Maximum indicated that the species had a wider distribution, extending northwards. Additionally, predictions for the future (2050 and 2070) indicated that the species will probably have a narrower distribution than at present, which will be shifted eastwards. The extended Bayesian skyline plot analysis, which provides a robust analysis of fluctuations in the effective population size throughout the evolutionary history of a species, produced results highly consistent with the ecological niche modelling predictions for the red-backed fairywren. This is the first study to investigate the Late Quaternary history of an endemic avian taxon from Australia using ecological niche modelling and Bayesian-based demographic analysis.

Temporal shifts in avian phenology across the circannual cycle in a rapidly changing climate: A global meta‐analysis

AbstractThe alteration of the timing of biological events is one of the best documented effects of climate change, with overwhelming evidence across taxa. Many studies have investigated the phenology of consumers, especially birds. However, most of these studies have focused on specific phenophases, whereas a global analysis of avian phenological trends during recent climate change across different phases of the circannual cycle is still lacking. Here, we performed a comprehensive meta‐analytic synthesis of the phenological responses (temporal shifts in days year−1) of birds across different phenophases (prebreeding migration, breeding, and postbreeding migration) by summarizing more than 5500 time series from 684 species from five continents during 1811–2018. Our results confirm that avian taxa have advanced prebreeding migration and breeding by ~2–3 days per decade, whereas no significant temporal changes in the timing of postbreeding migration were documented. Advancement in the timing of prebreeding migration and breeding strongly depended on migratory behavior, with the advance being the weakest for long‐distance migrants and the strongest for resident species. Diet generalists and primary consumers tended to advance prebreeding migration timing more than species with different dietary specializations. Increasing body size resulted in a larger advancement in the onset (but not in the mean date) of prebreeding migration and breeding, whereas phenological advances were larger in the northern than in the southern hemisphere. Our synthesis, covering most of the world, highlighted previously unappreciated patterns in avian phenological shifts over time, suggesting that specific life‐history or ecological traits may drive different responses to climate change.

Annual egg productivity predicts female-biased mortality in avian species.

Among avian species, the differential cost entailed by either sex in competition for mates has been regarded as the main evolutionary influence on sex differences in mortality rates. However, empirical evidence suggests that sex-biased adult mortality is mainly related to differential energy investment in gamete production, with a greater annual mass devoted to egg production leading to higher female mortality. We explicitly tested the generality of this pattern in a comparative framework. Annual egg production can be relatively large in some species (up to 200% of female body mass) and annual mortality is generally biased toward females. We showed that greater annual egg productivity resulted in higher mortality rates of females relative to males. Mating system was secondarily important, with species in which males were more involved in mating competition having more equal mortality rates between the sexes. However, both traits explained only a limited fraction of the interspecific variation in female-biased mortality. Other traits, such as sexual size dimorphism and parental care, had much weaker influences on female-biased mortality. Our results suggest that both annual mass devoted to gamete production by females and mating system contribute to the evolution of the fundamental life-history trade-off between reproduction and survival in avian taxa.

High Prevalence of Plasmodium Infection in Fighting Cocks in Thailand Determined with a Molecular Method.

Avian malaria caused by Plasmodium and the malaria-like parasites of the genus Haemoproteus has been regularly described in multiple regions worldwide. These parasites significantly affect many avian taxa, including domestic chickens and fighting cocks. There are limited epidemiological studies of these blood parasites in vertebrate hosts, especially in Thailand. This study used microscopic examination of blood samples and PCR amplification exploiting primers for nucleotide sequences of Plasmodium or Haemoproteus species based on the cytochrome b gene to determine the occurrence of Plasmodium spp. in fighting cocks. Examination of 249 blood samples of fighting cocks revealed that 41.37% (103/249) were positive for malaria by microscopic examination and 88.76% (221/249) were positive by DNA amplification. Sequencing and DNA analysis of 61 PCR products revealed that infection by Plasmodium juxtanucleare was the most common avian malaria in fighting cocks in Thailand followed by infections by Plasmodium gallinaceum; however, Haemoproteus infection was not discovered. This study indicated that plasmodiasis is widespread in fighting cocks in Thailand although the prevalence was not clearly determined; therefore, prevention and control strategies for these protozoa should be improved, especially those for avoiding vector exposure and eliminating mosquito breeding sites.

Updating splits, lumps, and shuffles: Reconciling GenBank names with standardized avian taxonomies

Abstract Biodiversity research has advanced by testing expectations of ecological and evolutionary hypotheses through the linking of large-scale genetic, distributional, and trait datasets. The rise of molecular systematics over the past 30 years has resulted in a wealth of DNA sequences from around the globe. Yet, advances in molecular systematics also have created taxonomic instability, as new estimates of evolutionary relationships and interpretations of species limits have required widespread scientific name changes. Taxonomic instability, colloquially “splits, lumps, and shuffles,” presents logistical challenges to large-scale biodiversity research because (1) the same species or sets of populations may be listed under different names in different data sources, or (2) the same name may apply to different sets of populations representing different taxonomic concepts. Consequently, distributional and trait data are often difficult to link directly to primary DNA sequence data without extensive and time-consuming curation. Here, we present RANT: Reconciliation of Avian NCBI Taxonomy. RANT applies taxonomic reconciliation to standardize avian taxon names in use in NCBI GenBank, a primary source of genetic data, to a widely used and regularly updated avian taxonomy: eBird/Clements. Of 14,341 avian species/subspecies names in GenBank, 11,031 directly matched an eBird/Clements; these link to more than 6 million nucleotide sequences. For the remaining unmatched avian names in GenBank, we used Avibase’s system of taxonomic concepts, taxonomic descriptions in Cornell’s Birds of the World, and DNA sequence metadata to identify corresponding eBird/Clements names. Reconciled names linked to more than 600,000 nucleotide sequences, ~9% of all avian sequences on GenBank. Nearly 10% of eBird/Clements names had nucleotide sequences listed under 2 or more GenBank names. Our taxonomic reconciliation is a first step towards rigorous and open-source curation of avian GenBank sequences and is available at GitHub, where it can be updated to correspond to future annual eBird/Clements taxonomic updates.

Patterns of single limb forces during terrestrial and arboreal locomotion in rosy-faced lovebirds (Psittaciformes: Agapornis roseicollis).

The biomechanical demands of arboreal locomotion are generally thought to necessitate specialized kinetic and kinematic gait characteristics. While such data have been widely collected across arboreal quadrupeds, no study has yet explored how arboreal substrates influence the locomotor behavior of birds. Parrots - an ancient arboreal lineage that exhibit numerous anatomical specializations towards life in the trees - represent an ideal model group within which to examine this relationship. Here, we quantifiy limb loading patterns within the rosy-faced lovebird (Agapornis roseicollis) across a range of experimental conditions to define the circumstances under which arboreal gaits are triggered, and how, during arboreal walking, gait patterns change across substrates of varying diameter. In so doing, we address longstanding questions as to how the challenges associated with arboreality affect gait parameters. Arboreal locomotion was associated with the adoption of a sidling gait, which was employed exclusively on the small and medium diameter poles but not terrestrially. When sidling, the hindlimbs are decoupled into a distinct leading limb (which imparts exclusively braking forces) and trailing limb (which generates only propulsive forces). Sidling was also associated with relatively low pitching forces, even on the smallest substrate. Indeed, these forces were significantly lower than mediolateral forces experienced during striding on terrestrial and large diameter substrates. We propose that the adoption of sidling gaits is a consequence of avian foot morphology and represents a novel form of arboreal locomotion where inversion/eversion is impossible. Such movement mechanics is likely widespread among avian taxa and may also typify patterns of arboreal locomotion in humans.

The impact of diet quality on the velocity, morphology and normality of sperm in the zebra finch Taeniopygia guttata

ABSTRACTSperm traits can influence fertilisation success, but there is still much we do not understand about sperm condition dependence, that is, how much sperm traits depend on the male's energy acquisition and allocation. This is especially pronounced in avian taxa, despite extensive observational studies and sampling in wild populations. In this study, we collected sperm samples before and after experimentally reducing diet quality of wild-derived captive zebra finches in small mixed-sex groups, which we compared with individuals on a control diet. We measured the length of sperm components (head, midpiece, flagellum and total sperm length), the proportion of sperm with normal morphology, the proportion of sperm that were progressively motile and sperm swimming velocity (curvilinear velocity; VCL). The only sperm trait we found to be impacted by reduced diet quality was a significant decrease in sperm midpiece length. This is consistent with emerging evidence in other non-model systems, as well the fact that diet can alter mitochondrial density and structure in other tissue types. There was also a significant decrease in sperm velocity and the proportion of motile sperm over the course of the experiment for both experimental groups (i.e. unrelated to diet). This decrease in sperm velocity with largely unchanged sperm morphology emphasizes that there are other important determinants of sperm velocity, likely including seminal fluid composition.

Cooperative breeding behavior emerges early in restored populations of the Brown-headed Nuthatch (Sitta pusilla)

We monitored the emergence of cooperative breeding behavior in 2 Brown-headed Nuthatch (Sitta pusilla) populations that were reintroduced to formerly occupied sites in south Florida. Individuals from presumed family groups were captured and moved (n = 48) in the first reintroduction attempt (1998–2001) on Everglades National Park, Florida, USA. Two cooperative breeding groups were observed in the second breeding season (2000) and the proportion of cooperative breeding groups increased to ∼20% of the territories present in year 5. The second reintroduction attempt focused on capture and release of juveniles (n = 30) onto Jonathan Dickinson State Park, Florida, USA. A cooperative breeding group was observed in the first breeding season (2019) of this second attempt and in the 2 breeding seasons that followed (2020–2021). Cooperative breeding behavior was observed in both reintroduction attempts when nuthatches occupied a small fraction of the available habitat. Habitat saturation has been linked to cooperative breeding behavior in other avian taxa, but our observations point to the potential influence of other factors in promoting cooperation in the nuthatch. Recent studies suggest these factors might include mate limitations, benefits derived from group activities, and direct benefits of co-breeding among >2 adults.

The Enigmatic Avian Oogenus Psammornis: A Review of Stratigraphic Evidence

Psammornis rothschildi is an avian taxon established by Andrews in 1911 on the basis of eggshell fragments surface-collected near the city of Touggourt, in the north-eastern part of the Algerian Sahara. Since the initial discovery, a number of Psammornis specimens have been reported from various localities in North Africa (Algeria, Tunisia, Libya, Mauritania) and the Middle East (Saudi Arabia, Iran). Most of the finds lack a stratigraphic context, which has resulted in considerable confusion about the geological age of Psammornis, with attributions ranging from the Eocene to the Holocene. A review of the available evidence shows that only two groups of localities provide reasonably reliable stratigraphic evidence: the Segui Formation of SW Tunisia, apparently of latest Miocene age, and the Aguerguerian (Middle Pleistocene) of NW Mauritania. This suggests a fairly long time range for Psammornis. Psammornis eggs are, in all likelihood, those of giant ostriches, although the lack of associated skeletal material makes it difficult to interpret the eggshell fragments in evolutionary terms. However, the oological record suggests that giant ostriches have been present in Africa since the late Miocene, which leads to the reconsideration of some hypotheses about the palaeobiogeographical history of the Struthionidae. The lack of Psammornis eggs transformed by humans suggests that this giant ostrich did not survive until Epipalaeolthic or Neolithic times.

Diurnal activity patterns, habitat use and foraging habits of Egyptian goose (Alopochena egyptiacus Linnaeus, 1766) in the Boyo wetland, southern Ethiopia

Egyptian goose (Alopochena egyptiacus) is a resident bird species in Africa South of the Sahara occurring throughout the entire Nile Valley. Despite the wide distribution, the available information on its behavioral ecology is limited in Ethiopia. A study on the activity patterns, habitat use and foraging habits of Egyptian goose was carried out in and around Boyo wetland, Ethiopia, during the dry and wet seasons. Scan sampling method was used to study the activity patterns and habitat use of Egyptian goose in grassland, mudflat and shallow water habitats of the wetland. The feeding behavior of Egyptian goose was also observed in the surrounding farmland habitats using scan sampling method. Generally, Egyptian geese spent most of their time resting (39.81%) followed by foraging (32.64%). They spent 10.43% of their time in comfort movement preening or stretching. The rest of their time was allocated for locomotion (6.63%), vigilance (5.75%), and social behavior (1.59%), and other activities (2.86%). Most of the birds were engaged in foraging activity in the morning (07:00-9:00 h) and afternoon (16:00 - 18:00 h) hours both during the wet and dry seasons. About 39% of Egyptian geese were scanned in mudflat, 31.5% in grassland, and 30.05% in shallow water habitats engaged in different activities. Most individuals used the grassland habitat for foraging during the dry (59.5%) and wet (74%) seasons, while they used shallow water and mudflat habitats for resting both during the wet and dry seasons seasons. The birds were observed foraging mainly grass during the dry (93.62%) and wet (59.52%) seasons. The Egyptian geese show diurnal activity pattern with feeding peaks in early morning and late afternoon hours as is observed in many other avian taxa. The Boyo wetland is also as an important foraging ground for this species and other birds in the area. Further ecological studies on the species and impact of human activities on the Boyo wetland should be conducted for the conservation of the avifauna.

Nutrient sources for offspring formation: diet–mother and mother–offspring isotope discrimination in domesticated gallinaceous birds

ABSTRACT Stable isotope techniques can be used to assess nutrient acquisition and allocation strategies used to produce offspring. Before stable isotope techniques can be employed, researchers need reliable isotope discrimination values. In this context, isotope discrimination compares the difference in the isotope ratio between the maternal–offspring tissue that occurs during nutrient transfer prior to egg laying. Currently, isotope discrimination values are unknown between the maternal blood constituents – that reflect different temporal scales of integration – and downy feathers of their offspring. In this study, we experimentally derive isotope discrimination relationships between maternal diet–blood constituents for egg laying, and between maternal blood constituents–down feathers of offspring in an experiment with 3 types of domesticated gallinaceous birds raised on known diets. Our experiment is the first to report isotope discrimination values for maternal blood constituents–down of offspring in avian taxa and provides a new sampling technique that is less invasive than previously available as collecting down does not require sampling viable eggs or individuals. Future researchers can use these results to assist in identifying nutrient sources used by adult birds to produce young.