Andrew Hamer

Institute of Aquatic Ecology · Centre for Ecological Research

Cities can host significant biological diversity. Yet, urbanisation leads to the loss of habitats, species, and functional groups. Understanding how multiple taxa respond to urbanisation globally is essential to promote and conserve biodiversity in cities. Using a dataset encompassing six terrestrial faunal taxa (amphibians, bats, bees, birds, cara...

River–floodplain ecosystems play a crucial role in connecting landscape patches through hydrological connectivity, but they are among the most threatened ecosystems. Floodplains provide important habitat for amphibians by connecting aquatic and terrestrial habitats. Modifications to floodplain hydrology can impact amphibian communities, yet few stu...

Aim Changes to the extent and severity of wildfires driven by anthropogenic climate change are predicted to have compounding negative consequences for ecological communities. While there is evidence that severe weather events like drought impact amphibian communities, the effects of wildfire on such communities are not well understood. The impact o...

Road traffic often inflicts higher mortality rates on amphibians than other vertebrates, especially where roads bisect migration pathways. To facilitate safe movements by amphibians between non-breeding and breeding habitats, under-road tunnels are being increasingly installed together with barrier fencing or walls. However, few observational studi...

Urbanisation adversely affects the abiotic and biotic characteristics of watercourses, including freshwater streams that support the development of stream-breeding salamanders. We conducted a study over four years on an isolated fire salamander population inhabiting a stream valley northwest of Budapest, Hungary. Our aim was to understand aspects o...

Urbanisation threatens species through habitat loss, isolation and fragmentation. Greenspace in urban landscapes often provides connectivity and habitat for wetland-dependent species. Accessible greenspace measures the combined effects of movement barriers (e.g., roads) and the total amount of greenspace on populations. I determined whether accessi...

Movement is an ecological process that affects individual fitness and population dynamics of species. Understanding movement patterns is crucial for the effective conservation of amphibian populations isolated by urban development. Here, we conducted a capture–recapture study over 6 years in a population of the fire salamander ( Salamandra salamand...

Metacommunity ecology provides a basis for understanding how ecological communities are assembled. Metacommunity theory can be applied to assess the effects of anthropogenic disturbance on freshwater communities. However, few studies have examined how species-specific responses to environmental covariates can generate broader patterns in freshwater...

Life history theory provides a basis for understanding how amphibians persist within landscapes fragmented by urbanisation. To quantify the life history traits of a population susceptible to habitat disturbance, we implemented a capture-recapture study of an isolated population of the fire salamander (Salamandra salamandra) within an urbanised catc...

Roads threaten animal species through habitat loss, fragmentation and degradation, and direct mortality. It is crucial to understand how species respond to linear infrastructure for effective conservation of animal communities in fragmented landscapes. We assessed relationships between amphibian abundance and roads/ railways and habitat fragmentati...

A fundamental goal of community ecology is to understand species‐habitat relationships and how they shape metacommunity structure. Recent advances in occupancy modeling enable habitat relationships to be assessed for both common and rare species within metacommunities using multi‐species occupancy models (MSOM). These models account for imperfect s...

Populations of aquatic-breeding amphibians are declining from habitat loss, fragmentation and degradation. Identifying how populations are affected by landscape barriers such as roads is essential for conservation and requires understanding the processes underpinning species occupancy in fragmented landscapes. Here, I assessed relationships between...

Urbanisation is causing rapid land-use change worldwide. Populations of freshwater turtles are vulnerable to impacts of urbanisation such as habitat loss, fragmentation and degradation, because many species require interconnected aquatic and terrestrial habitats. Understanding the processes that underpin survival in urban areas is critical in manag...

ContextHabitat loss and habitat fragmentation negatively affect amphibian populations. Roads impact amphibian species through barrier effects and traffic mortality. The landscape variable ‘accessible habitat’ considers the combined effects of habitat loss and roads on populations. Objectives The aim was to test whether accessible habitat was a bett...

Environmental managers have the difficult task of ensuring species persistence despite considerable uncertainty about their response to management. Spatially explicit population models provide one solution for simulating the dynamics of species and evaluating alternative management regimes. We used a Bayesian model to investigate wetland occupancy...

Roads are detrimental to wildlife populations that require contiguous networks of terrestrial and aquatic habitats. Many species of freshwater turtles are sensitive to habitat fragmentation caused by roads, and are susceptible to road mortality during overland migrations. The common long-necked turtle (Chelodina longicollis) is an Australian freshw...

Two pervasive and fundamental impacts of urbanization are the loss and fragmentation of natural habitats. From a genetic perspective, these impacts manifest as reduced genetic diversity and ultimately reduced genetic viability. The growling grass frog (Litoria raniformis) is listed as vulnerable to extinction in Australia, and endangered in the sta...

Amphibian populations are at risk of adverse impacts from roads and traffic. Roads constructed in the vicinity of wetlands and streams often interrupt amphibian movement pathways and can prevent individuals from accessing critical habitats. High numbers of amphibians are either deterred from crossing or killed by traffic, contributing to population...

Urbanization is worldwide among the biggest threats to amphibian populations. However, hardly any studies have been conducted on the effects thereof in developing countries. Amphibian distribution and community assemblages are not well understood in aquatic and terrestrial habitats that are rapidly changing due to human modification. We conducted f...

Many amphibians in Europe and North America regularly use under-road tunnels during dispersal. However, such structures have not been shown to mitigate the impacts of road mortality on frog populations in Australia. We tested the behavioural response of three Australian frog species to a 12-m amphibian under-road tunnel in controlled ex situ condit...

Context Species vary broadly in their ability to adapt to urbanisation. Freshwater turtles are vulnerable to the loss and degradation of terrestrial and aquatic habitat in urban environments. There have been few publications investigating impacts of urbanisation on freshwater turtles in Australia. Aims We investigated the effects of urbanisation on...

While the principles and steps to be followed in the recovery of a declining species are relatively straightforward, there is often a considerable gap between the theory and practice. One example is the decline of the bell frog complex in eastern Australia, which is comprised of three species: Litoria aurea, L. castanea, and L. raniformis. There is...

Fish introduced into wetlands can impact amphibian populations through predation on eggs and larvae. While relationships among hydroperiod, habitat complexity and predation on amphibian larvae have been examined in relatively natural freshwater ecosystems, they have not been explicitly considered in urban landscapes. We examined these relationships...

Urbanisation is currently impacting frog and reptile species worldwide through the loss of native habitats. Broad changes in the distribution and abundance of frog and reptile species in the Melbourne area were assessed from 1850-2006 using historical sources and wildlife databases. A total of six species of frogs (out of 16 species) and 26 species...

Stormwater retention ponds in urbanizing catchments are constructed to collect and treat runoff from impervious surfaces. Amphibians often inhabit retention ponds, which may partly offset the loss of natural wetlands resulting from urbanization. We investigated the use of retention ponds by frogs in a rapidly-urbanizing region of south-eastern Aust...

Urbanization is currently responsible for widespread declines of amphibian populations globally through the loss, isolation, and degradation of habitat. However, it is not clear how urbanization affects amphibian communities at both local (pond) and landscape scales. We assessed the breeding distribution of frogs in ponds along an urban-rural gradi...

Amphibian populations have suffered declines and disappearances around the world. It is now recognized that many of the disappearances were the result of infection by the amphibian chytrid fungus Batrachochytrium dendrobatidis (Bd). Most global declines were first observed in the 1980s. Here, we used information from museum collections, natural-his...

Habitat loss and habitat isolation have contributed to declines in the green and golden bell frog (Litoria aurea) over much of its former range in south-eastern Australia. Understanding the parameters critical for the persistence of extant populations is required to halt further declines. We assessed waterbody occupancy in a local network of potent...

Urbanization involves the conversion of natural habitats into human-modified ecosystems and is known to reduce the diversity and abundance of indigenous plant and animal communities. Urbanization may lead to the extinction of indigenous species or facilitate the establishment of non-indigenous communities in cities and towns. We analysed sighting r...

Conservation of pond-breeding frogs requires information on movement patterns within populations. The Green and Golden Bell Frog (Litoria aurea) is endangered in New South Wales, Australia; yet little is known about its movement biology. To inform conservation planning and habitat restoration, we conducted a mark-recapture study to describe the mov...

Urbanisation currently threatens over one-third of the world’s known amphibian species. The main threats of urbanisation to amphibian populations are habitat loss, habitat fragmentation and isolation, and degradation of habitat quality. A complex array of interacting biotic and abiotic factors impact amphibians in urban and urbanising landscapes. T...

Populations of the threatened Growling Grass Frog Litoria raniformis in metropolitan Melbourne currently occur in human-made habitats and there is little information on their current status. We conducted systematic field surveys at 28 waterbodies within a population distributed over agricultural land in the Pakenham area, on the south-eastern urban...

We investigated the habitat correlates of five amphibian species and species-richness in freshwater ponds at a wetland site in New South Wales, Australia. The objective was to produce a simple model useful to wildlife managers in the area wishing to construct new ponds for the purpose of amphibian conservation. 43 ponds were surveyed in which we fo...

Declining species of vertebrates, including amphibians, have a life history that is characterised by low fecundity, long time to maturity, limited capacity to disperse and habitat specialisation. However, by studying aspects of the life history of an endangered amphibian in south-eastern Australia we show that a paradox may exist for some declining...

Evidence is provided that fertilizer use increased markedly from the 1960s in New South Wales (NSW), south-eastern Australia. The agrochemicals probably accumulated on agricultural land until 1974, when they were washed or leached after heavy rains into waterbodies that may have been occupied by the endangered green and golden bell frog (Litoria au...

Amphibians use a range of microhabitats as retreat sites to escape adverse climatic conditions. We conducted two outdoor experiments using a brick pile and shallow trays of water containing aquatic vegetation to assess retreat site selection during winter in the endangered frog Litoria aurea. A multivariate habitat model in the first experiment ind...

Increased production of frogs is expected as markets increase and wild stocks dwindle. With conventional rearing techniques, high tadpole densities lower metamorphosis weight, and increase metamorphosis time (MT) and variation. These problems result from low water quality and competition for feed. In this study, tadpoles of Litoria aurea, a species...

The introduction of fish has decimated many amphibian populations through increased predation, primarily on their larvae. Some amphibian species now occupy marginal habitats as a response to the presence of introduced fish predators. Such habitats may include ephemeral water bodies where fish do not usually occur, although breeding in these subopti...

The range of the green and golden bell frog (Litoria aurea) has undergone a widespread yet unexplained contraction in south-eastern Australia since the mid 1970s, and the species is now listed as endangered in the New South Wales Threatened Species Conservation Act 1995 and as vulnerable in the federal Environmental Protection and Biodiversity Cons...

The range of the green and golden bell frog (Litoria aurea) has undergone a widespread yet unexplained contraction in southeastern Australia since the mid 1970s, and the species is now listed as endangered in the New South Wales Threatened Species Conservation Act 1995 and as vulnerable in the federal Environmental Protection and Biodiversity Conse...

Twelve species were present, representing two families and six genera. Breeding activity data and relative abundance for each species was tabulated according to the species habitat preferences. The Melaleuca vegetation community contained the highest species abundance and diversity. The frog faunal assemblages of Redhead Lagoon is present in a regi...