Avian Behavior Research Articles

Parrots as overlooked seed dispersers

Parrots as overlooked seed dispersers

Stop and Smell the Pollen: The Role of Olfaction and Vision of the Oriental Honey Buzzard in Identifying Food.

The importance of olfaction for various avian behaviors has become increasingly evident. So far, the use of olfaction for food detection among raptors has only been demonstrated for Cathartes vultures. The Oriental honey buzzard (Pernis orientalis) is a resident and migrant in Taiwan and regularly forages in apiaries. One of its foods in apiaries is yellow pollen dough, a softball-sized mixture of pollen, soybeans, and sugar that beekeepers provide as a supplementary food for bees. Given that pollen dough is not similar to any naturally occurring food, we hypothesized that buzzards identify the dough’s nutritious contents using olfaction, perhaps in combination with vision. Using a series of choice experiments in which individuals could choose between two doughs, we showed that (1) buzzards almost unerringly chose pollen-containing over pollen lacking doughs when otherwise the doughs were identical in size, shape, and yellow color; (2) buzzards always preferred yellow over black or green doughs if both doughs contained pollen; (3) buzzards still preferred pollen-containing over pollen-lacking doughs when both doughs were black, but at a lower rate than in (1). We statistically excluded the possible influences of the doughs’ relative brightness or of repeat visits by the same individuals. Our experiments thus suggest the use of a ‘multi-modal foraging strategy’ among buzzards whereby olfaction and vision are likely to be both used in identifying food at close distances. We also estimated the olfactory receptor gene repertoire size in the buzzard’s genome which is almost five times as large as that of three other raptor species. Therefore, olfaction is likely of far greater ecological importance to this species than to other raptor species. We suggest that olfaction should be considered in the design of behavioral and genetic studies to better understand the use of multiple senses in avian behaviors.

A high-accuracy, time-saving method for extracting nest watch data from video recordings

Understanding inter- and intraspecific variation in parental care has been an important focus in studies of avian behaviour and evolution. Unfortunately, typical methods for quantifying parental care, such as field observation and video recordings, can be extremely time-consuming. Here, we demonstrate that utilizing behavioural analysis software, such as EthoVision XT, can reduce time required for video data extraction by 37−69 %. This method is highly accurate; results and error rates did not differ from those of manual observation. We suggest this method could be beneficial and time-saving for studies analyzing large amounts of video recordings.

Prospects for integrating avian behavior in the management of agroecosystems on tropical islands: the case of food crops in Martinique, French West Indies

Si les oiseaux sont consideres comme un enjeu patrimonial, leurs comportements alimentaires sont une menace potentielle pour les productions agricoles vivrieres. Leur prise en compte apparait primordiale pour repondre a des objectifs de gestion concertee associant la conservation de la biodiversite a une activite agricole economiquement viable. Cette double representation des oiseaux participe a en qualifier certains d’especes a risques pour les cultures. Or, l’avifaune des milieux agricoles se caracterise par la predominance d’especes ubiquistes dont les comportements alimentaires contribuent certes au developpement de comportements dommageables a la production agricole, mais permet aussi des comportements alimentaires benefiques ou sans effets. L’approche ethologique phenomenologique, retenue pour identifier les comportements, confirme que le registre comportemental d’une meme espece peut inclure des comportements alimentaires dommageables ainsi que d’autres sans impacts, voire meme benefiques a la production agricole.

Black Sparrowhawk brooding behaviour in relation to chick age and weather variation in the recently colonised Cape Peninsula, South Africa

Understanding the effects climate change may have on animal populations relies on establishing which environmental conditions shape their behaviour and subsequent reproductive output, fitness or survival. South Africa has seen significant warming trends and changes in precipitation over the last few decades; however, the ways in which these trends are likely to influence animal populations are still relatively poorly understood. The Black Sparrowhawk (Accipiter melanoleucus) has expanded its range in South Africa and recently colonised the Cape Peninsula in the Western Cape, a region that experiences a Mediterranean climate. In this study, we examined the brooding behaviour of this species, a vital trait for reproductive success, in the Cape Peninsula breeding population. We examined the influence of chick age as well as temperature, rainfall and wind speed on parental brooding. Additionally, the effect of prey provisioning on brooding was investigated. In our analyses, we used data on brooding from nest cameras together with weather data collected at a fine temporal scale (1 h). The variable with the strongest influence on parental brooding was chick age. This variable showed a non-linear relationship. Initially chicks were brooded >50 % of the time; however after 3 weeks brooding declined rapidly. The proportion of time spent brooding increased with decreasing temperatures, while rainfall and wind speed showed a positive correlation with the amount of brooding. Our model predicted that in common winter conditions of the Western Cape (15 °C, 10 km/h wind speed, 1 mm/h rainfall) A. melanoleucus breeding pairs spent nearly 100 % of their time brooding young chicks (7 days old) to protect them from detrimental weather. Our results highlight measurable effects of weather patterns on avian behaviour at a key stage of the life cycle. Changes in weather conditions predicted for this region will likely further benefit this range-expanding species.

Disjunct Nocturnal Roosting by a Yellow-rumped Warbler (Setophaga coronata) during Migratory Stopover

ABSTRACT Nocturnal roosting at locations disjunct from daytime foraging areas (hereafter disjunct nocturnal roosting) is a common avian behavior on both the breeding and wintering grounds but to our knowledge has not been documented in arboreal passerines during migratory stopover. We report observations of a spring migrant Yellow-rumped Warbler (Setophaga coronata) commuting to a nocturnal roost site 2.6–3.2 km north from its 5.1–9.0 ha daytime home ranges on two consecutive stopover days. We discuss the potential significance of this behavior in terms of roost habitat type, predator avoidance, and thermoregulation. We encourage those conducting telemetry studies on stopover migrants to examine existing data and, when possible, to use tracking methods that advance understanding of the behavioral ecology of nocturnal roosting and the prevalence of and causes for disjunct roosting.

Breeding origin and spatial distribution of migrant and resident harriers in a Mediterranean wintering area: insights from isotopic analyses, ring recoveries and species distribution modelling

Variation in avian migratory behaviour is widespread, not only among species but also within species, and can involve shifts from sedentary at low latitudes to migratory at high latitudes. This leads to a situation whereby non-migratory populations of a species at lower latitudes are periodically joined by migratory conspecifics during winter. Determining spatio-temporal dynamics in distribution and structure of different populations is crucial to our understanding of their ecology and interactions, but it is often difficult or impossible to separate resident from migrant populations. Here, we used the winter distribution of Marsh Harrier (Circus aeruginosus) in the Iberian Peninsula (southwest Europe) to analyse the potential of spatial distribution models and stable isotope analyses of feathers (deuterium, δ2H) to evaluate differences in spatial distribution of migrant and resident raptor populations in southern Europe. Overall, ring recoveries and isotopic assignment showed that most migrant harriers wintering in the Iberian Peninsula had a central and northern latitudinal European origin. Our results revealed segregation in the winter distribution of migrant and resident Marsh Harrier populations in the Iberian Peninsula. These results have important conservation implications, suggesting that ecological conditions and potential stressors could greatly differ among resident and migrant populations in winter. Our approach provided a useful methodological procedure to evaluate the wintering spatial segregation of European populations of a raptor species and presents a new challenge to the study of their ecological consequences.

The sources of diurnal variation in caching behaviour of South Island Robins (Petroica australis australis)

There have been few studies of the food-storing behaviour of short-term scatter-hoarding birds in relation to differences in ambient temperature. In this study we examined the patterns of caching behaviour of 13 male South Island Robins (Petroica australis australis) in relation to the time of day and ambient temperature. We predicted that cold conditions would cause a stress-induced increase in caching behaviour in birds. We also predicted that birds would cache the greatest number of food items (mealworms) in the morning and that the numbers of items cached would decline throughout the day. We found that there was a negative relationship between the numbers of mealworms cached and temperature and that the numbers of mealworms that birds cached throughout the day declined. Finally, we also found that there was a positive relationship between the total number of mealworms that birds cached and their daily gains in mass. This study shows that at low temperatures, energy is more valuable to birds when stored internally than it is for other caching species as other taxa (e.g. parids) increase caching as temperature decreases. Our results also support theoretical models of avian caching behaviour, which show that birds should reduce the absolute number of food items they cache throughout the day as they prepare for their nightly fasts.

Temporal and environmental influences on the vocal behaviour of a nocturnal bird

Temporal and environmental variation in vocal activity can provide information on avian behaviour and call function not available to short‐term experimental studies. Inter‐sexual differences in this variation can provide insight into selection effects. Yet factors influencing vocal behaviour have not been assessed in many birds, even those monitored by acoustic methods. This applies to the New Zealand kiwi (Apterygidae), for which call censuses are used extensively in conservation monitoring, yet which have poorly understood acoustic ecology. We investigated little spotted kiwi Apteryx owenii vocal behaviour over 3 yr, measuring influences on vocal activity in both sexes from time of night, season, weather conditions and lunar cycle. We tested hypotheses that call rate variation reflects call function, foraging efficiency, historic predation risk and variability in sound transmission, and that there are inter‐sexual differences in call function. Significant seasonal variation showed that vocalisations were important in kiwi reproduction, and inter‐sexual synchronisation of call rates indicated that contact, pair‐bonding or resource defence were key functions. All weather variables significantly affected call rates, with elevated calling during increased humidity and ground moisture indicating a relation between vocal activity and foraging conditions. A significant decrease in calling activity on cloudy nights, combined with no moonlight effect, suggests an impact of light pollution in this species. These influences on vocal activity provide insight into kiwi call function, have direct consequences for conservation monitoring of kiwi, and have wider implications in understanding vocal behaviour in a range of nocturnal birds.

Real-time in vivo uric acid biosensor system for biophysical monitoring of birds

Research on birds has long played an important role in ecological investigations, as birds are relatively easily observed, and their high metabolic rates and diurnal habits make them quite evidently responsive to changes in their environments. A mechanistic understanding of such avian responses requires a better understanding of how variation in physiological state conditions avian behavior and integrates the effects of recent environmental changes. There is a great need for sensor systems that will allow free-flying birds to interact with their environment and make unconstrained decisions about their spatial location at the same time that their physiological state is being monitored in real time. We have developed a miniature needle-based enzymatic sensor system suitable for continuous real-time amperometric monitoring of uric acid levels in unconstrained live birds. The sensor system was constructed with Pt/Ir wire and Ag/AgCl paste. Uricase enzyme was immobilized on a 0.7 mm sensing cavity of Nafion/cellulose inner membrane to minimize the influences of background interferents. The sensor response was linear from 0.05 to 0.6 mM uric acid, which spans the normal physiological range for most avian species. We developed a two-electrode potentiostat system that drives the biosensor, reads the output current, and wirelessly transmits the data. In addition to extensive characterization of the sensor and system, we also demonstrate autonomous operation of the system by collecting in vivo extracellular uric acid measurements on a domestic chicken. The results confirm our needle-type sensor system's potential for real-time monitoring of birds' physiological state. Successful application of the sensor in migratory birds could open up a new era of studying both the physiological preparation for migration and the consequences of sustained avian flight.

Simulated Birdwatchers’ Playback Affects the Behavior of Two Tropical Birds

Although recreational birdwatchers may benefit conservation by generating interest in birds, they may also have negative effects. One such potentially negative impact is the widespread use of recorded vocalizations, or “playback,” to attract birds of interest, including range-restricted and threatened species. Although playback has been widely used to test hypotheses about the evolution of behavior, no peer-reviewed study has examined the impacts of playback in a birdwatching context on avian behavior. We studied the effects of simulated birdwatchers’ playback on the vocal behavior of Plain-tailed Wrens Thryothorus euophrys and Rufous Antpittas Grallaria rufula in Ecuador. Study species’ vocal behavior was monitored for an hour after playing either a single bout of five minutes of song or a control treatment of background noise. We also studied the effects of daily five minute playback on five groups of wrens over 20 days. In single bout experiments, antpittas made more vocalizations of all types, except for trills, after playback compared to controls. Wrens sang more duets after playback, but did not produce more contact calls. In repeated playback experiments, wren responses were strong at first, but hardly detectable by day 12. During the study, one study group built a nest, apparently unperturbed, near a playback site. The playback-induced habituation and changes in vocal behavior we observed suggest that scientists should consider birdwatching activity when selecting research sites so that results are not biased by birdwatchers’ playback. Increased vocalizations after playback could be interpreted as a negative effect of playback if birds expend energy, become stressed, or divert time from other activities. In contrast, the habituation we documented suggests that frequent, regular birdwatchers’ playback may have minor effects on wren behavior.

Causes of extra-pair paternity and its inter-specific variation in socially monogamous birds

Based on molecular technology, researchers find that extra-pair paternity (EPP) prevails among socially monogamous bird species. This phenomenon challenges traditional views of sexual selection and mating system, and has become one of the hot-spots in the avian behavior ecology. This review focuses on the evolutionary causes leading to EPP and the potential factors affecting it. Early studies of EPP in birds used a wide variety of tools, including plumage color polymorphism, polymorphic enzymes, and sex-differences in estimation of the heritability of morphological traits. Although each of these methods can be used to estimate the likelihood that EPP are present or absent in a population, none of them provide enough accurate estimation to allow meaningful cross-species comparison. Currently, studies of EPP mainly use “DNA-methods”, namely multi-locus mini-satellite fingerprints, single-locus mini-satellite fingerprints, and micro-satellite genotyping, because they can provide accurate outcome of paternity identification and their results are reproducible. From the point of the female, the driving forces for EPP are that females may gain direct benefits or indirect genetic benefits from EPP. Hypotheses explaining the benefits include fertility assurance, good genes, genetic compatibility, and genetic diversity. Despite large numbers of theoretically plausible explanations for EPP, there have been few direct empirical tests that can provide unambiguous support for only one type of explanation. The most straightforward test of the genetic benefit hypothesis of extra-pair copulation is a comparison of the performance of maternal half-siblings from multiply sired broods. Some highly-cited landmark studies spectacularly support the genetic benefit hypothesis, while other studies failed to reveal any systematic differences in maternal half-sibling performance, even in the same species or in taxonomically closely-related species. Briefly, the point that purpose of extra-pair copulation is to gain genetic benefits is still facing great challenges. Therefore, some researchers suggest that more attention should be focused on the interactions between parties involved in the extra-pair paternity phenomenon. Others, however, believe that such interactions can also be of a cooperative nature, and involve exchange of direct benefits. In brief, an approach focusing on interactions (involving either conflict or cooperation) seems to be the most promising direction to improve our understanding of the phenomenon of extra-pair paternity. As for the factors leading to intra- and inter-specific variation in the level of EPP, current researches mainly focus on the breeding density, breeding synchrony, the complexity of the habitat, paternal care, adult mortality, food availability, and genetic diversity. Explaining intra- and inter-specific variation in the extent of EPP has been difficult, but an appreciation of the problems of small sample sizes, and an ever-increasing comparative database have led to several recent advances. It now seems probable that differences between species in the rate of EPP are due to a combination of differences in life history, pattern of parental care, and local opportunities for promiscuity. In a word, although there have been a lot of theoretical and empirical researches about EPP of birds, no consensus on the basic questions has been received in this area. Thus, more scientific statistical analysis method and more empirical experiments are still badly needed to improve the theoretical system.

Avian foraging behaviour in relation to provision of ecosystem services in a highland East African agroecosystem

Capsule Most birds in a Kenyan highland agroecosystem foraged from the ground, potentially contributing to weed regulation, and invertebrate intake rates by aerial foraging insectivores were high, indicating that birds could contribute to pest regulation. Aims Bird foraging behaviour and its implications for provision of ecosystem services and crop damage was investigated. Methods Detailed observations of foraging birds in relation to substrates used and food items consumed were undertaken within cultivated areas during dry and wet seasons. Results Most birds foraged from the ground, often consuming seeds, fruits and flowers from weeds rather than crop plants. The relatively high rate of invertebrate intake by two aerial foraging species and the high number of insectivorous bird species recorded in the area suggest that invertebrate predation could also be high and potentially contribute to pest regulation. Species-specific differences in the habitats birds used and prey taken were also identified, providing an indication of species likely to contribute to invertebrate and weed pest control and those likely to cause crop damage. Conclusion The results describe species-specific avian foraging behaviour in African farmland that may be used in informing agricultural management practices to enhance beneficial species and reduce impacts of crop-damaging ones.

The effects of climate change on avian migratory patterns and the dispersal of commercial poultry diseases in Canada - Part I

Many birds are able to modify migratory strategies when selection favours an adjustment. Climate change is provoking a range of responses from avian migrants and affecting their relationship with other biological systems. This is the first part of a two-part review that aims to summarise the available literature on the impact of climate change on migratory birds and how those changes will subsequently affect the spread of poultry diseases. Part I reviews the effects of climate change on the ecology of avian migrants; it was found that climate change has evoked several changes in birds, including changes in avian phenology, poleward shifts in avian distributions, modification of migratory distances, direction and activity, and alterations to movement patterns and destinations. Based on predictions for future climatic trends, climate change will continue to favour changes in avian migratory strategies and behaviour, emphasising the importance of investigating how these adjustments will affect the relationship between avian migrants and bird-borne pathogens.

Zebra Finches Build Nests that do not Resemble their Natal Nest

Nests are built by nearly all bird species and can be extremely varied in their structural characteristics, both within and among species. As with a number of other avian behaviours, it seems plausible that early learning might be important in producing adult nest-building behaviour. To examine whether preferences that adults have for nest materials are related to their early-life experience, we experimentally manipulated the colour of the nest in which Zebra Finch pairs built and raised chicks. We then tested these chicks at maturity to determine whether they preferred the colour of the nest from which they had fledged or preferred the same colour as their father. We also examined the overall structure of nests that fathers and their sons built to determine whether the nest a male builds resembles that from which he hatched. When males and females naïve to building were paired as adults and tested for their nest material preferences, they did not prefer the colour of their natal nest. When these males were re-paired and their preference tested a second time, the majority then preferred the colour that their father had preferred (which was also the colour preferred by most of the males). The structural components of a male's nest did not resemble the nest built by his father, but neither did his father's nests resemble each other. We found no evidence that the experience of the nest from which a bird fledges influences his preferences for the colour of nest material or the structure of his first nest.

Predator Vocalizations Alter Parental Return Time at Nests of the Hooded Warbler

Abstract. A growing body of evidence indicates that vocalizations of predators and perceived risk of predation can significantly alter avian nesting behavior and reproductive performance. However, it is currently unclear whether birds acoustically discriminate among different types of predators and adjust their short-term behavioral responses accordingly. We investigated this issue via playback experiments in which nests of the Hooded Warbler (Setophaga citrina) were exposed to vocalizations of two nest predators, the Blue Jay (Cyanocitta cristata) and Eastern Chipmunk (Tamias striatus), and a dangerous predator of adults and nestlings, Cooper's Hawk (Accipiter cooperii). We used songs of a common nonpredatory passerine, the Red-eyed Vireo (Vireo olivaceus), as a control. In comparison to responses observed during control trials, adult Hooded Warblers delayed their return to the nest following playback of Cooper's Hawk but returned more quickly after playback of the Eastern Chipmunk, probably because Coop...

The Application of Temperature Data Loggers for Remotely Monitoring the Nests of Emei Shan Liocichla (Liocichla omeiensis)

Temperature data loggers (TDL) are mostly used to monitor avian incubation behavior in bird studies. In this paper we demonstrate how TDL can also be used to determine different breeding stages and nest success of the vulnerable Emei Shan Liocichla (Liocichla omeiensis). All nests that contained at least one egg were divided into two groups. Group I included six nests monitored traditionally by the observers' visits, while Group II included eight nests monitored by TDL. Group I and Group II were visited every 1-4 days and 7 days, respectively, to check nest contents and status (e.g., active vs. inactive, and the breeding process) until fledging or nest failure. The time of each observation was recorded to verify the interpretation of TDL. The data recorded by TDL were converted into line graphs of temperature against time and assessed visually. The results indicated that TDL can reliably identify different breeding stages and estimate daily nest survival rates (DSR) and total nest success. The nest success of Group II (0.3015) was higher than that of Group I (0.2387), suggesting that deployment of TDL did not negatively influence nest survival rate of Emei Shan Liocichla. In contrast to traditional nest visits, TDL minimized disturbance by observers and provided a more precise estimate of nest survival. We suggest that TDL should be used more widely in studies of the breeding ecology of rare and endangered birds.

The bird of time: cognition and the avian biological clock

Avian behavior and physiology are embedded in time at many levels of biological organization. Biological clock function in birds is critical for sleep/wake cycles, but may also regulate the acquisition of place memory, learning of song from tutors, social integration, and time-compensated navigation. This relationship has two major implications. First, mechanisms of the circadian clock should be linked in some way to the mechanisms of all these behaviors. How is not yet clear, and evidence that the central clock has effects is piecemeal. Second, selection acting on characters that are linked to the circadian clock should influence aspects of the clock mechanism itself. Little evidence exists for this in birds, but there have been few attempts to assess this idea. At its core, the avian circadian clock is a multi-oscillator system comprising the pineal gland, the retinae, and the avian homologs of the suprachiasmatic nuclei, whose mutual interactions ensure coordinated physiological functions, which are in turn synchronized to ambient light cycles (LD) via encephalic, pineal, and retinal photoreceptors. At the molecular level, avian biological clocks comprise a genetic network of “positive elements” clock and bmal1 whose interactions with the “negative elements” period 2 (per2), period 3 (per3), and the cryptochromes form an oscillatory feedback loop that circumnavigates the 24 h of the day. We assess the possibilities for dual integration of the clock with time-dependent cognitive processes. Closer examination of the molecular, physiological, and behavioral elements of the circadian system would place birds at a very interesting fulcrum in the neurobiology of time in learning, memory, and navigation.

Factors Influencing Behavior of Wetland Birds in the Rainwater Basin during Spring Migration

As little is known about specific factors influencing wetland birds during migration, the effects of time period, hunting pressure, and year on wetland bird behavior were evaluated during spring migration. Avian behavior was quantified on 36–40 playa wetlands in the Rainwater Basin region of Nebraska, during springs 2002–2004. Multivariate analysis of variance was used to test for differences in behavior among time periods, hunting categories (closed to hunting, hunted wetlands in-season, and hunted wetlands post-season), and years for geese, dabbling ducks, diving ducks, and shorebirds, as well as among two species of management concern; Greater White-fronted Geese (Anser albifrons) and Northern Pintails (Anas acuta). Overall, goose behavior did not differ among time periods or years; however, a greater percentage of geese were observed feeding in wetlands closed to hunting (11%) than on hunted wetlands in-season (5%). A smaller percentage of dabbling ducks was observed feeding on hunted wetlands in-season (19%) than on wetlands closed to hunting (24%) or on hunted wetlands post-season (28%). Diving duck and shorebird behavior did not differ among time periods, years, or hunting categories. Although spring hunting was implemented to reduce the light goose population, it may also be negatively influencing habitat quality at migration stopover sites for geese and dabbling ducks. Managers should consider limiting spring hunting disturbance on temporary and seasonal wetlands, where dabbling ducks spend more time foraging, than on semi-permanent wetlands.

Changing Perception of Avian Influenza Risk, Hong Kong, 2006–2010

Changing Perception of Avian Influenza Risk, Hong Kong, 2006–2010