Colleen T Downs

University of KwaZulu-Natal | ukzn · School of Life Sciences

Diadromous macrocrustaceans need connectivity between the ocean, estuary and river to complete their life cycle. Instream barriers in lower reaches of rivers threaten upstream migrations of diadromous macrocrustaceans. Varuna litterata migrate upstream after a spawning event out at sea. These migration events have been poorly documented. We documen...

Monitoring species' habitat selection and microhabitat requirements is vital for conservation and management, though studies on bird species' habitat selection at relatively fine scales are often limited. Camera traps are useful techniques for studying bird communities, particularly elusive species that are challenging to document using traditional...

Fish behaviour is one biological organisational level regularly used to assess the state of freshwater ecosystems and can be monitored using fish telemetry methods. The development of activity sensors incorporated into fish telemetered tags allows for non-spatial movement to be detected and is increasingly used to understand the energy budgets and...

Forest transformation has major impacts on biodiversity and ecosystem functioning. Identifying the influence of forest habitat structure and composition on avian functional communities is important for conserving and managing forest systems. This study investigated the effect of forest structure and composition characteristics on bird species commu...

Context Recreational angling has a history of species introductions causing significant loss of native biodiversity. Despite this, it represents a large economy supporting many livelihoods. The Mooi River, South Africa, supports trout fisheries in its upper reach. A weir was constructed to mitigate the loss of a natural barrier, now inundated by a...

The histology and growth of reptilian and crocodilian claws (ungues) have been extensively studied; however, Nile crocodile ( Crocodylus niloticus ) claws have not received adequate attention. Furthermore, age estimations for reptilian claws remain unexplored, despite Nile crocodile claws being used in long‐term dietary reconstruction studies, assu...

Generally, urbanisation affects biodiversity negatively; however, some species thrive in urban areas. One mammalian species thriving in the urban forest mosaic landscape is the vervet monkey (Chlorocebus pygerythrus), particularly in Durban, eThekwini Municipality, KwaZulu-Natal Province, South Africa. Vervet monkeys’ spatial use can provide import...

Bird song mediates speciation but little is known about its genetic basis because of the confounding effect of vocal learning in model systems. Rhythm, in particular, transcends acoustic communication across the animal kingdom and plays a fundamental role in sexual selection and species recognition in birds. Here we investigated the genomic underpi...

Human population increase and anthropogenic land-use changes are impacting biodiversity globally. Despite an increasing trend in urban wildlife studies, a systematic assessment of mammalian small carnivores in urban areas is still lacking. We evaluated urban studies in international peer-reviewed journals using a systematic review process. We asses...

The manual processing and analysis of videos from camera traps is time-consuming and includes several steps, ranging from the filtering of falsely triggered footage to identifying and re-identifying individuals. In this study, we developed a pipeline to automatically analyze videos from camera traps to identify individuals without requiring manual...

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 surro...

Context Protected areas are important in mitigating threats to biodiversity, including land conversion. Some of the largest protected areas are located in biodiverse savanna systems where a mosaic of land-uses exist beyond their borders. The protected areas located in such systems are often host to threatened species and diverse animal communities....

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 man...

Ground-nesting bird species are typically threatened when their natural habitats are removed or altered through urbanisation. Despite this, some species, like the Spotted Thick-knee (Burhinus capensis), persist in urban mosaic landscapes. Our study was undertaken to collect novel information on Spotted Thick-knee persistence in an urban mosaic land...

The manual processing and analysis of videos from camera traps is time-consuming and includes several steps, ranging from the filtering of falsely triggered footage to identifying and re-identifying individuals. In this study, we developed a pipeline to automatically analyze videos from camera traps to identify individuals without requiring manual...

Nest-building is an energetically expensive activity for birds. Consequently, some species opportunistically use other species’ nests. The Hamerkop Scopus umbretta, an endemic sub-Saharan African waterbird, constructs one of the largest nests of any bird in the world. Little is documented on the role of Hamerkop nests in the breeding biology of oth...

Microhabitats play a significant role in the persistence of mammalian species and communities. In South Africa, the forest biome is the smallest. It includes the naturally fragmented Southern Mistbelt Forest group, where little is known about contemporary mammalian assemblage dynamics concerning these forest's microhabitats. We determined the micro...

Corvids are known for their urban exploitation, often using artificial infrastructure to roost and nest. In many areas of its distribution range, the pied crow (Corvus albus) is often common in areas of anthropogenic land use, often breeding and foraging near human settlements. In this study, we monitored pied crow use of cellular telecommunication...

The common hippopotamus ( Hippopotamus amphibius ) is a driver of ecological processes in African savannah aquatic and terrestrial ecosystems. Recent studies have highlighted the ecological impacts of hippos in these systems; however, these lack behavioural data to contextualise their ecological inputs. We fitted global positioning system (GPS) tra...

Apex predators typically affect the distribution of key soil and vegetation nutrients through the heterogeneous deposition of prey carcasses and excreta, leading to a nutrient concentration in a hotspot. The exact role of central-place foragers, such as tropical raptors, in nutrient deposition and cycling, is not yet known. We investigated whether...

Storks are a conspicuous pan-global freshwater flagship taxon with 20 extant species, all of which have been accorded IUCN Red List status. Red List assessments use a combination of scientific evidence and expert inputs to develop species-level status, but there is little careful evaluation of whether these assessments are comparable across species...

Diurnal basking (“sunning”) is common in many ectotherms and is generally thought to be a behavioural mechanism for thermoregulation. Recent studies have reported the occurrence of nocturnal basking in a few distantly-related species of freshwater turtles, but the true extent of this behaviour is unknown, and it may be underreported due to sampling...

Continuous human expansion is affecting landscape composition, in particular through urbanisation. Wildlife persistence in the urban mosaic is generally negatively affected; however, many primate species show behavioural plasticity and thrive in the urban mosaic. Urban primates often show selective behaviours in the urban mosaic, e.g. responses to...

Conservationists speculated on potential benefits to wildlife of lockdown restrictions because of the COVID-19 pandemic but voiced concern that restrictions impeded nature conservation. We assessed the effects of lockdown restrictions on biodiversity conservation in South Africa, a biodiverse country with economic inequality and reliance on wildlif...

The Rose-ringed Parakeet Psittacula krameri has established feral populations in South African suburban areas. However, the information on the breeding biology of parakeets remains poorly documented in the country. We assessed parakeets' breeding status and behaviour by locating their roost and breeding sites in Durban, eThekwini Metropole, KwaZulu...

Background and Aims For the first time in Africa, two freshwater turtle species (hereafter terrapin) presence and temporal activity in their habitats were investigated using radio telemetry. Methods Telemeter tags were attached to Pelusios sinuatus ( n = 10) at Ndumo Reserve and Pelomedusa galeata ( n = 10) at Tala Reserve. Pelusios sinuatus tagge...

Murid rodents are considered globally important invasive species, yet they are still sold in the pet trade. Little is known about the genetic diversity of traded rodents, and many species are incorrectly identified in the pet trade. We used mitochondrial gene regions to assess the taxonomy and genetic diversity of 149 rodents sold in pet shops acro...

Resource selection functions (RSFs) are among the most commonly used statistical tools in both basic and applied animal ecology. They are typically parameterized using animal tracking data, and advances in animal tracking technology have led to increasing levels of autocorrelation between locations in such data sets. Because RSFs assume that data a...

Globally with the human population increase, urban expansion has increased, impacting biodiversity and ecosystem functions. Visitation of fruiting trees by vertebrate frugivores can influence the persistence of fleshy fruited trees and so further maintain frugivore communities in transformed landscapes. Figs (Ficus spp.) have been recognised as key...

Camera traps have been used increasingly as a research tool to monitor wildlife globally, and have become more advanced, thereby improving their performance and lowering costs. Their use has allowed researchers to study a range of species, including rare and elusive species, particularly in remote areas, in a non-invasive, reliable and cost-effecti...

This presentation displayed some different results to a previous upload due to past, constructive conference, reviewer commentary and a change in modelling procedure. The title encapsulates our most important findings but some simpler results are also displayed.

Gaping is a regularly observed behaviour in crocodilians globally but is still poorly understood in relation to external variables which could trigger this behaviour. The occurrence of gaping behaviour was investigated in a large wild population of Nile crocodiles (Crocodylus niloticus) during the dry and wet seasons at Nyamithi Pan, Ndumo Game Res...

Understanding changes in the population density of cryptic gamebirds may be useful for land managers when designing or adjusting grassland management regimes to conserve these species and the grasslands. The population density of Red-winged Francolin (Scleroptila levaillantii) indicates the presence of their preferred grassland habitat. Pointing do...

Invasive alien plants can use animal-plant interactions to increase their invasiveness. This study investigated the role of frugivorous birds in seed dispersal, germination success and germination time of the alien plant Pyracantha angustifolia (Franch.) C.K. Schneid. (Rosaceae) in South African high elevation grasslands. We monitored which bird sp...

African forests have been negatively affected because of human impacts. The use of forest products is high for lower-income communities. Excessive logging alters the forest patch structure and composition, causing degradation. In addition, increases in bushmeat hunting for sustenance and trade result in increased pressures on forest mammalian speci...

Many of the world’s most biodiverse regions are found in the poorest and second most populous continent of Africa; a continent facing exceptional challenges. Africa is projected to quadruple its population by 2100 and experience increasingly severe climate change and environmental conflict—all of which will ravage biodiversity. Here we assess conse...

Alien invasive plant species are a major problem globally, threatening ecosystem functioning and biodiversity. Native bird species facilitate their spread through mutualistic relationships. Studies of seed dispersal of alien invasive plants are important for effective management. In the present study, we investigated the role of native bird species...

Invasive alien plant species have been identified as a major threat to biodiversity and the relationship with native avian dispersers may increase their invasion potential. The impact of invasive plant species needs to be quantified using comparable assessment tools across different habitats and species to allocate limited resources to high-priorit...

Common hippopotamus (Hippopotamus amphibius) (hereafter hippos) are iconic and understudied ecological engineers in African aquatic and terrestrial systems. Temporal changes in hippo group size in response to changes in wading areas have been described in river systems, but hippo group dynamics remain generally understudied and have not been quanti...

Anthropogenic habitat conversion through urban sprawl is driving mesocarnivores to modify their behaviour and ecology. Thorough knowledge of their feeding ecology is fundamental in understanding the pressures imposed on mesocarnivores by urbanisation. The diet of the water mongoose Atilax paludinosus has been studied in natural habitats of KwaZulu-...

The Rose-ringed Parakeet Psittacula krameri (Scopoli, 1769) has become invasive in several countries, including South Africa, mainly through the pet trade releases and escapees. We conducted an online questionnaire survey targeting the residents in Durban, eThekwini Municipality, KwaZulu-Natal, South Africa. We aimed to determine the distribution,...

Urbanisation has increasingly encroached on numerous bird species' natural habitats, generally negatively affecting their persistence. Furthermore, increased human-wildlife interactions may benefit or be detrimental to the long term persistence of these species. The Spotted Thick-knee (Burhinus capensis), a ground-nesting species, persists in some...

Pointing dogs (Canis lupus familiaris) are primarily used to locate cryptic species or evidence thereof and often to establish their abundance. Environmental conditions at the time of search may influence the probability that a dog will detect a target. Here, we aimed to determine the environmental factors that affected the detection rate of a poin...

Most vulture species worldwide are in decline and of conservation concern. Despite the growing attention to vultures, relatively few studies have focused on their breeding behaviour. Understanding all aspects of a species’ behaviour and its behavioural needs could help to inform conservation efforts. Behavioural studies can be enhanced with the use...

Non‐native species have been translocated from their native to new geographic ranges through the pet trade. Consequently, some become threatened with extinction, while some establish and become invasive. We surveyed 117 physical pet stores across South Africa between September 2018 and September 2019 to determine avian species composition, availabi...

Context Forest loss and fragmentation are major drivers of biodiversity decline globally. However, with the widely recognised notion that biodiversity is multifaceted, few studies have assessed the responses of different diversity metrics to forest landscape changes. Objectives Here, we used a multifaceted approach to assess the effects of landsca...

Resource selection functions are among the most commonly used statistical tools in both basic and applied animal ecology. They are typically parameterized using animal tracking data, and advances in animal tracking technology have led to increasing levels of autocorrelation between locations in such data sets. Because resource selection functions a...

Protected areas are intended as tools in reducing threats to wildlife and preserving habitat for their long-term population persistence. Studies on ranging behavior provide insight into the utility of protected areas. Vultures are one of the fastest declining groups of birds globally and are popular subjects for telemetry studies, but continent-wid...

Four anguillid eel species occur in the western Indian Ocean rivers of Africa: Anguilla bengalensis , Anguilla bicolor , Anguilla marmorata and Anguilla mossambica . These catadromous fishes face multiple stressors, including habitat alteration and deterioration, barriers to migration, pollution and the adverse impacts of alien species, but knowled...

The sale of live non‐native animals has become a social norm and is of global concern. The pet trade industry has become one of the main pathways where non‐native small mammals are introduced worldwide. We conducted a questionnaire survey in South African pet shops from September 2018 to September 2019 to gain insights into non‐native small mammali...

Anthropogenic activities have resulted in habitat loss and fragmentation across different landscapes. Anthropogenic land-uses adjacent to forest patches may further influence the movement and occupancy of a species. Therefore, we investigated how dominant land-uses, i.e. grassland, human settlement and commercial exotic timber plantations surroundi...

Globally, the threats of habitat loss and disease on amphibian survival have necessitated the creation of ex-situ insurance populations as a conservation tool. We initiated a captive breeding project to create an insurance population for the endangered Pickersgill's reed frog (Hyperolius pickersgilli Raw, 1982) at the Johannesburg Zoo from parents...

Raptors have crucial functions, both ecologically and as environmental indicators. Currently, many raptor species worldwide are threatened, and the potential loss of functional groups will yield dire consequences. We identified the trends and causes of raptor admissions to the Moholoholo Wildlife Rehabilitation Centre, Limpopo province, South Afric...

Changes to natural environments as a consequence of human population growth are a major threat to biodiversity. Natural habitat modifications, changes in vegetation structure and habitat characteristics have resulted in decreased species richness and functional diversity in wildlife populations. Species’ distributions, abundance and persistence are...

Figs (Ficus spp.) are a diverse taxon of woody plants that play keystone ecological roles. They provide nutritional and aseasonal fruit crops that are consumed by many frugivores, often in times of fruit scarcity. In a mutually beneficial relationship, the plants also benefit from seed dispersal by birds and mammals away from the parent plants enha...

The ever-increasing human population, globalisation, and desire to keep pets have resulted in the translocation of many species into non-native environments. As a result, some of the non-native reptile species have been introduced to South Africa through the pet trade. However, little is known about the extent of trade in reptiles via online and ph...

With open-access publishing authors often pay an article processing charge and subsequently their article is freely available online. These charges are beyond the reach of most African academics. Thus, the trend towards open-access publishing will shift the business model from a pay-wall model, where access to literature is limited, to a pay-to-pub...

Tourism can be a powerful tool for wildlife conservation if well controlled and responsibly managed. Apex predators constitute particularly attractive subjects for tourism, but simultaneously they may generate conflict with local communities. Harpy Eagles Harpia harpyja are the largest eagle species and are highly sought-after by ecotourists. The l...

Low-cost uncrewed aerial vehicles (UAVs) have become ubiquitous, and advanced UAV systems are affordable for many field ecologists and wildlife managers. Many hobbyist UAVs have been applied to ecological studies, but proprietary software limits their widespread application with little quantification with regards to their accuracy and efficiency in...

The increase in anthropogenic stress on river ecosystems is of growing concern globally as demand for water increases and freshwater ecosystem degradation occurs. Understanding how the species respond to these stressors is important to manage ecosystem functioning, the conservation of species and the ecosystem services they provide. We used radio t...

Increasing beach sediment loss from erosion and high levels of crab Ocypode spp. predation are threatening turtle nests and nesting habitat. The 900 m long beach on Cousine Island, Seychelles, supports a nesting population of approximately 70–130 hawksbill turtle Eretmochelys imbricata nests each season. Seasonal and storm-related erosion and accre...

Documenting phylogenetic diversity for conservation practice allows elucidation of ecosystem functioning and processes by highlighting the commonality and divergence of species' functional traits within their evolutionary context. Conserving distinct evolutionary histories has intrinsic value, and the conservation of phylogenetically diverse commun...

Understanding population trends is important when managing wildlife in protected areas. The common hippopotamus, Hippopotamus amphibius (hereafter hippo), is an iconic African species that, in South Africa, is mainly restricted to protected areas. Ndumo Game Reserve (NGR), South Africa, was established as a sanctuary for hippos in 1924. However, NG...