Arjun Amar

Percy FitzPatrick Institute of African Ornithology | PFIAO · Biological Sciences

Given the current biodiversity crisis, understanding how animals move across a landscape dotted with different anthropogenic threats and the consequences of those threats for animals is paramount to devising evidence‐based conservation interventions. Vultures roam across large areas and are highly exposed to poisoning, which represents a particular...

Dietary studies are essential to better understand raptor ecology and resource requirements through time and space, informing species habitat use, interspecific interactions and demographic rates. Methods used to collect data on raptor diets can constrain how dietary analyses can be interpreted. Traditional approaches to study raptor diets, such as...

There is increasing recognition of the potential pleiotropic effects of melanin pigmentation, particularly on immunity, with reports of variation in haemoparasite infection intensity and immune responses between the morphs of colour-polymorphic bird species. In a population of the black sparrowhawk (Accipiter melanoleucus) in western South Africa,...

The conversion of natural habitats to farmland is a major cause of biodiversity loss and poses the greatest extinction risk to birds worldwide. Tropical raptors are of particular concern, being relatively slow-breeding apex predators and scavengers, whose disappearance can trigger extensive cascading effects. Many of Africa’s raptors are at conside...

Traditionally, demographic monitoring of birds has been undertaken by intensive monitoring of nesting sites. However, this is challenging for low-density species, whereby the effort and costs involved in locating and monitoring remote sites can be prohibitive or even bias research findings. We show that Global Positioning System (GPS) tracking can...

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...

The rapid development of wind energy in southern Africa represents an additional threat to the already fragile populations of African vultures. The distribution of the vulnerable Cape Vulture Gyps coprotheres overlaps considerably with wind energy development areas in South Africa, creating conflicts that can hinder both vulture conservation and su...

Raptor polymorphisms have played an important role in understanding how evolutionary forces within and between populations operate. However, within a population little is known about the history of the polymorphism, the effects of any population bottlenecks, and the overall stability of the polymorphism. We investigated the stability of a melanin-b...

Urban areas provide breeding habitats for many species. However, animals raised in urban environments face challenges such as altered food availability and quality, pollution and pathogen assemblages. These challenges can affect physiological processes such as immune function and antioxidant defences which are important for fitness. Here, we explor...

ABSTRACT Traditional methods to study raptor diet are usually limited temporally, e.g., prey remains at nesting sites, and are unsuitable to examine dietary changes throughout the year. Using web-sourced photography, we explore temporal patterns in prey size and key prey species between sexes of the sexually dimorphic Eurasian Sparrowhawk (Accipite...

Traditional methods to study raptor diet are usually limited temporally, e.g., prey remains at nesting sites, and are unsuitable to examine dietary changes throughout the year. Using web-sourced photography, we explore temporal patterns in prey size and key prey species between sexes of the sexually dimorphic Eurasian Sparrowhawk (Accipiter nisus)...

Climate change and urbanization are two of the most important current global change drivers. However, most studies have focused on these issues in isolation, limiting our ability to predict the impacts of the two in tandem. During hot conditions, many birds reduce foraging activity to minimise heat gain, which can result in costly trade-offs, affec...

Concentrations of organochlorine pesticides have been extensively monitored in birds, particularly from higher trophic guilds such as raptors. While monitoring of raptors has been ongoing for decades, patterns from monitoring activities have never been summarised on a global scale. In this study, we undertake a review to better describe the monitor...

Sustainable offtake of any threatened species and objective monitoring thereof relies on data-driven and well-managed harvest quotas and permit compliance. We used web-sourced images of African leopard (Panthera pardus pardus) trophy hunts to determine whether online photographs could assist in monitoring and documenting trophy hunting in Africa. O...

Data from wildlife rehabilitation centers (WRCs) can provide on-the-ground records of causes of raptor morbidity and mortality, allowing threat patterns to be explored throughout time and space. We provide an overview of native raptor admissions to four WRCs in England and Wales, quantifying the main causes of morbidity and mortality , trends over...

Knowledge of a species' diet is fundamental for understanding its ecology. Many pre-existing methods are unable to distinguish diet between sex and age groups. Resulting information may be inaccurate when studying the diet of sexually dimorphic species. Unlike most other vertebrates, raptors display reversed sexual dimorphism with the female being...

The provision of anthropogenic food undoubtedly influences urban bird fitness. However, the nature of the impact is unclear, with both benefits and costs of urban diets documented. Moreover, the influence of short-term fluctuations in food availability, linked to urban weekday/weekend cycles of human presence, is largely unknown. We explored whethe...

Animal movement is mainly determined by spatial and temporal changes in resource availability. For wetland specialists, the seasonal availability of surface water may be a major determinant of their movement patterns. This study is the first to examine the movements of Shoebills ( Balaeniceps rex ), an iconic and vulnerable bird species. Using GPS...

The black sparrowhawk (Accipiter melanoleucus) is a color-polymorphic sub-Saharan raptor, with adults occurring in two discrete color morphs: dark and light. It has previously been suggested that plumage coloration is determined by a one-locus two-allele system, with the light allele being dominant over the dark allele. Here, we revisit that assump...

Many falcons ( Falco spp.) exhibit a distinct dark plumage patch below the eye, termed the malar stripe. This stripe is hypothesized to reduce the amount of solar glare reflected into the eyes while foraging, thereby increasing hunting efficiency in bright conditions. Here, we use a novel, global-scale correlative approach to test this ‘solar glare...

Conditions experienced during early life can have long-term individual consequences by influencing dispersal, survival, recruitment and productivity. Resource allocation during development can have strong carry-over effects onto these key parameters and is directly determined by the quality of parental care. In the black sparrowhawk (Accipiter mela...

The global lockdown to mitigate COVID-19 pandemic health risks has altered human interactions with nature. Here, we report immediate impacts of changes in human activities on wildlife and environmental threats during the early lockdown months of 2020, based on 877 qualitative reports and 332 quantitative assessments from 89 different studies. Hundr...

Vultures and condors are among the most threatened avian species in the world due to the impacts of human activities. Negative perceptions can contribute to these threats as some vulture species have been historically blamed for killing livestock. This perception of conflict has increased in recent years, associated with a viral spread of partial a...

As with many areas in Africa, Kenya has witnessed rapid human development in recent decades, including an increase in urbanization and an intensification of agriculture. The impact of these land use changes on wildlife populations have, however, rarely been examined. The Augur Buzzard is a widespread raptor species, thought to adapt relatively well...

The use of poison to eliminate predators is causing African vulture populations to collapse. To understand the prevalence and motivations of this practice we conducted an extensive survey with South African commercial farmers. Using a specialised questioning technique and ad hoc quantitative methods we found that an estimated 22% and 31% of farmers...

Diet differences between the sexes and ages have often been recorded for bird species. Many raptor species show extreme sexual size dimorphism with females often considerably larger than the males and these differences may be reflected in their diets. Diet studies in raptors most frequently focus on analysing prey remains or pellets collected at ne...

With the rapid growth of wind energy developments world‐wide, it is critical that the negative impacts on wildlife are considered and mitigated. This includes minimising the number of large soaring raptors, which are killed when they collide with wind turbines. To reduce the likelihood of raptor collisions, turbines should be placed at locations wh...

The Bearded Vulture Gypaetus barbatus is a Critically Endangered species in Southern Africa whose entire range in the Southern Hemisphere falls within the Maloti-Drakensberg mountains of South Africa and Lesotho. Here we synthesize 20 years of research on this population to quantify the decline in the species, investigate the potential drivers for...

Protected areas are central to the conservation of biodiversity across the globe. However, their performance, especially in relation to highly mobile species, is largely dependent on the socio-ecological characteristics of the landscape that surrounds them. Here, we assess the patterns of avian scavenger distribution, including both obligate (i.e.,...

Blood parasites can impact host fitness and can, thus, act as selective agents in their host’s evolution. The melanocortin system linked to colouration of vertebrates may infer higher parasite resistance via pleiotropic properties of the genes involved. Black Sparrowhawks (Accipiter melanoleucus) are colour polymorphic (dark and light morph adults)...

Urban areas can be attractive to certain species because of increased food abundance and nesting availability, which in turn may increase productivity or breeding rates. However, there are also potential costs associated with urban living such as higher nest failure, poorer body condition, or increased prevalence of disease. These costs may result...

Disassortative mating in color-polymorphic raptors is a proposed mechanism for the maintenance of color polymorphism in populations. Selection for such a mating system may occur if there are fitness advantages of mating with a contrasting morph. In the black sparrowhawk (Accipiter melanoleucus), mixed-morph pairs may have a selective advantage beca...

As the world’s human population increases, transformation of natural landscapes into urban habitats continues to increase. In Africa, rates of human population growth and urbanisation are among the highest in the world, but the impacts of these processes on the continent’s biodiversity remain largely unexplored. Furthermore, the effects of ongoing...

Under the current African vulture crisis, supplementary feeding sites (SFS), which provide carrion resources, have become a popular conservation tool to address vulture declines. In South Africa, this practice is unregulated and the context in which SFS operate and their adherence to best management practices is currently unknown. In this study, we...

Aim Urban biodiversity, and its associated ecosystem services, is an important component of the quality of life of urban residents. The "luxury effect" posits a positive association between biodiversity and socioeconomic status in urban areas, and is thus reflective of environmental injustice, as the benefits associated with biodiversity are not eq...

The southern African population of Bearded Vultures Gypaetus barbatus has declined rapidly and it is threatened with extinction. In response to this decline and the additional threats of wind farm developments in the core of the species’ range, it has been proposed to establish a reintroduced population within their historic South African range as...

African White-backed Vultures were recently uplisted to ‘Critically Endangered’ by IUCN due to declines across their range. Poisoning is widely accepted as the major reason for these declines. Botswana supports a high number of this species (breeding pairs > c.1,200), but as yet no published information exists on their breeding success in the count...

In this study, we explore blood parasite prevalence, infection intensity, and co-infection levels in an urban population of feral pigeons Columba livia in Cape Town. We analyze the effect of blood parasites on host body condition and the association between melanin expression in the host's plumage and parasite infection intensity and co-infection l...

Old world vultures are the most threatened group of raptors globally. Supplementary feeding sites (SFS) are a popular conservation tool, widely used to assist vulture populations. Despite their popularity, the impact of SFS on vultures remains largely unstudied. A lack of knowledge on the number, distribution and management of SFS is a key factor h...

Within highly urban systems, anthropogenic activity often fluctuates cyclically, e.g. between weekdays and weekends. Thus, urban species may regularly experience significant changes in human activity and anthropogenic food abundance over very short time scales. Knowledge of how urban birds cope with such fluctuations may improve our understanding o...

In many vertebrates, productivity and survival usually increase with age and then start to decline above a certain age; processes known as reproductive and actuarial senescence. Senescence is widely believed to be driven by the accumulation of somatic damage or mutations. Thus, levels of such cellular damage, and therefore senescence could, in theo...

In many vertebrates, productivity and survival usually increase with age and then start to decline above a certain age; processes known as reproductive and actuarial senescence. Senescence is widely believed to be driven by the accumulation of somatic damage or mutations. Thus, levels of such cellular damage, and therefore senescence could, in theo...

The Moon cycle exposes nocturnal life to variation in environmental light. However, whether moonlight shapes the fitness of nocturnal species with distinct colour variants remains unknown. Combining data from long-term monitoring, high-resolution global positioning system tracking and experiments using prey, we show that barn owls (Tyto alba) with...

In many vertebrates, productivity and survival usually increase with age and then start to decline above a certain age; processes known as reproductive and actuarial senescence. Senescence is widely believed to be driven by the accumulation of somatic damage or mutations. Thus, levels of such cellular damage, and therefore senescence could, in theo...

To avoid predation, many species rely on vision to detect predators and initiate an escape response. The ability to detect predators may be lower in darker light conditions or with darker backgrounds. For birds, however, this has never been experimentally tested. We test the hypothesis that the response time of avian prey (feral pigeon Columbia liv...

In polymorphic species of birds, clinal variation in plumage coloration is frequently observed. These clines often follow Gloger’s ecogeographical rule, which predicts that greater numbers of dark morphs will breed in wetter areas. More recent research on polymorphic raptors has suggested this pattern might be due to a cryptic advantage of dark mor...

The Luxury Effect hypothesizes a positive relationship between wealth and biodiversity within urban areas. Understanding how urban development, both in terms of socioeconomic status and the built environment, affects biodiversity can contribute to the sustainable development of cities, and may be especially important in the developing world where c...

The near-threatened Lilian’s Lovebird Agapornis lilianae is a small parrot endemic to the Zambezi basin in south-east Africa. The species has a fragmented distribution predominantly within mopane woodlands and is widely referred to as a mopane specialist. The harvesting of mopane trees for charcoal production and timber are having widespread impact...

Vigilance is amongst the most universal of anti‐predator strategies and commonly declines with increasing group size. We experimentally manipulated predation risk in a system with a known relationship between group size and vigilance levels to explore whether this relationship changes in response to elevated predation risk. We investigated the vigi...

Identifying patterns of wildlife crime is a major conservation challenge. Here, we test whether deaths or disappearances of a protected species, the hen harrier, are associated with grouse moors, which are areas managed for the production of red grouse for recreational shooting. Using data from 58 satellite tracked hen harriers, we show high rates...

Understanding a species' diet can be critical for effective conservation. While several traditional methods for assessing raptor diet exist, many pose inherit biases and often require extensive fieldwork that can limit sample sizes and the geographic scope of studies. This is especially true for species that nest at low densities (e.g., large eagle...

In polymorphic species of birds, clinal variation in plumage coloration is frequently observed. These clines often follow Gloger's ecogeographical rule, which predicts that greater numbers of dark morphs will breed in wetter areas. More recent research on polymorphic raptors has suggested this pattern might be due to a cryptic advantage of dark mor...

Lead poisoning is an important threat to some raptor species, and the primary source of lead is through the ingestion of carcasses that have been shot with lead, which makes scavengers such as vultures particularly vulnerable. We examined the concentrations of lead in blood and bone tissue samples collected throughout the range of the Bearded Vultu...

Raptors provide critical ecosystem services, yet there is currently no systematic, global synthesis of their conservation status or threats. We review the International Union for the Conservation of Nature's Red List to examine the conservation status, distributions, threats, and conservation recommendations for all 557 raptor species. We further a...

Africa supports breeding populations of over 20% of all raptor species globally and over 20 regular Palearctic migratory raptors. Here, we discuss the importance of Africa in terms of the diversity of both resident and migrant species, the ecosystem services they provide, and the threats they face. We examine the state of knowledge of African rapto...

For many species, there is evidence that breeding performance changes as an individual ages. In iteroparous species, breeding performance often increases through early life and is expected to level out or even decline (senesce) later in life. An individual's sex and conditions experienced in early life may also affect breeding performance and how t...

Unlike smaller raptors, which can readily use flapping flight, large raptors are mainly restricted to soaring flight due to energetic constraints. Soaring comprises of two main strategies: thermal and orographic soaring. These soaring strategies are driven by discrete uplift sources determined by the underlying topography and meteorological conditi...

Across Africa, many raptor species, especially vultures, are in steep decline. Botswana is regionally important for numerous raptor species including vultures, but recent population trends of raptors within this country are totally unknown. In 2015-2016 we repeated road transects for raptors across northern Botswana that were first conducted in 199...

Global urbanization is rapidly increasing, specifically within Africa. However, the effects of these processes on Africa's wildlife are largely unexplored. For many species, the effects are detrimental, whereas others are able to colonize these human-altered environments and can even thrive. Raptors are positioned at the top of the food chain and t...

Lead (Pb) toxicity caused by the ingestion of Pb ammunition fragments in carcasses and offal is a threat to scavenging birds across the globe. African vultures are in critical decline, but research on whether Pb exposure is contributing to declines is lacking. In Africa, recreational hunting represents an important economic activity; however, Pb in...

Colour polymorphism may be maintained within a population by disruptive-selection. One hypothesis proposes that different morphs are adapted to different ambient light conditions, with lighter morphs having a selective advantage in bright conditions and darker morphs having advantages in darker conditions. The mechanism for this advantage is propos...