Levels Of Habitat Disturbance Research Articles

Quantifying forest disturbance regimes within caribou (Rangifer tarandus) range in British Columbia.

Habitat disturbance is a major driver of the decline of woodland caribou (Rangifer tarandus caribou) in Canada. Different disturbance agents and regimes negatively impact caribou populations to different degrees. It is therefore critical that land managers and scientists studying caribou have a detailed understanding of the disturbance regimes affecting caribou habitat. In this work we use recent advances in satellite-based disturbance detection to quantify polygonal forest disturbance regimes affecting caribou ecotypes and herds in British Columbia (BC) from 1985 to 2019. Additionally, we utilize this data to investigate harvesting rates since the implementation of the Species at Risk Act (SARA) and publication of recovery strategies for caribou in BC. Southern Mountain caribou herds are the most threatened yet experienced the highest rates of disturbance, with 22.75% of forested habitat within their ranges disturbed during the study period. Over the study period, we found that in total, 16.4% of forested area was disturbed across all caribou herd ranges. Our findings indicate that caribou in BC face high, and in many cases increasing, levels of habitat disturbance. Our results provide a detailed understanding of the polygonal disturbance regimes affecting caribou in BC at the herd scale, and highlight the need for effective implementation of policies aimed at preserving caribou habitat.

Response of Odonata assemblages to disturbance in urban freshwater habitats

AbstractUrbanisation continues to increase at an alarming rate and its effects on the natural environment are very profound now more than ever. Moreover, studies on terrestrial urban landscapes seems to be more than that on urban freshwater habitats. Furthermore, studies have shown that the Odonata are effective indicators of the effects of urbanisation on freshwater habitats. However, not much is known about their responses to urbanisation in sub‐Saharan Africa, especially given the unique set of conditions that characterise the area. Therefore, this study was conducted to investigate differences in Odonata responses, measured as the proportion of habitat generalists, to three levels of habitat disturbance in the Cape Coast Metropolis of Ghana. Results showed that Phaon camerunensis was a potential indicator of habitat disturbance. Also, differences in habitat disturbance significantly affected Odonata composition. The most important variables that influenced Odonata responses were the individual and interaction effects of altitude and preservation of riparian vegetation. Therefore, conservation strategies that are targeted at reducing the impacts of urbanisation on Odonata must focus on these variables.

Terrestrial small mammal community structure in a relic forest and anthropogenic habitats in Man region, Western Côte d’Ivoire

Terrestrial small mammals play important ecological roles in tropical ecosystems. They are regularly used to measure the level of habitat disturbance. This study aimed to determine the impacts of human activities on the species composition and relative abundance of terrestrial small mammal communities in Man region. Four types of habitats, including a relic forest, a […]

Exploring the management and integration of national parks in Northern Ethiopia: The case of Kafta Shiraro National Park

The study was conducted in Kafta-Shiraro in Northern region of Ethiopia. The study uses two important parameters to realize the objective of the study investigating themanagement and integration of the park, one is studying and explaining the community perceptions towards elephant (flagship species) conservation in Kafta Shiraro National Park (KSNP) and secondly compare and contrast the population structure and density of the (economically important plant) Boswellia papyrifera (Del.) Hochst inside and outside of the protected areas and the study contribute to the scientific bases for improved management of biodiversity and its conservation system. A total of 100 households were selected from 10 villages using a stratified random sampling. A rapid vegetation assessment survey was conducted in two Boswellia stands, inside the park and outside the park at villages in order to examine the status of the resource base. A total of 40 sample plots of size 20 X 20 m were laid at regular interval along parallel transects with smaller sample plots of size 5 X 5 m nested in the center of each plot for regeneration count. The conflicts between humans and wildlife in KSNP have been getting worse over time and underline the need to find a workable solution to stop the progress of encroaching human activities that are core factors in the conflict. The underlying factors were found to be free encroachment into the wildlife home ranges, mainly for cultivation and dry wood collection. The factors that contributed to the poor conservation of African elephant included weak community awareness and understaffed anti-poaching and patrolling team of the KSNP. The improper land use by host settlers locally called “wefrizemet” as well as legal settlers maximizes the level of habitat disturbance (threat of the elephants in the park) due to illegal cultivation with high number of livestock crossing to the park. B. papyrifera population structure illustrates that natural regeneration is lacking in all two study areas. Additionally, the population of Boswellia in the study areas is unstable and under threat due to lack of recruitments through regeneration. Based on the stands structure analysis, it is hypothesized that lack of natural regeneration is primarily caused by livestock grazing pressure and the absence of recruitment is largely caused by lack of seed production by mother trees as the result of intensive tapping of the frankincense. KSNP is deteriorating due to a lack of integration and development cooperation between the Park and the surrounding local community as well as administration the minimal managerial and institutional capacity of the Park, minimal alternative livelihoods for the surrounding communities, inadequate commitment among all officials in taking the Park as an issue of development agenda, absence of legal procedures and understandings on expansion of large scale farms, unplanned and non-integrated land use systems, and a lack of appropriate outreach programs needed to change the attitudes of the surrounding communities. Collaborative Park management is urgently required to rescue KSNP; agreement should be made from National to Woreda level stakeholders.

Anthropogenic disturbance promotes the abundance of a newly introduced butterfly, the European common blue (Polyommatus icarus; Lepidoptera: Lycaenidae), in Canada

The frequency of introductions of non-native species is increasing worldwide, but only a few introduced species undergo rapid population growth and range expansion, and even fewer become invasive, leading to negative impacts on native communities. Predicting which non-native species are likely to become widespread and abundant can be difficult when there is a lack of species’ information in the early stages of colonization. Here, we investigate the ecology of a newly introduced butterfly in Canada, the European common blue (Polyommatus icarus (Rottemberg, 1775)), by modelling its local- and landscape-scale habitat suitability in Montréal, Quebec, Canada, and the surrounding region, and by assessing its dispersal ability using a mark–release–recapture study. At a local scale, we found that P. icarus abundance was highest at sites with moderate levels of habitat disturbance (e.g., mowed every 2–3 years), the presence of their preferred larval host plant and low proportional cover of grasses. At a landscape scale, P. icarus abundance increased with an increasing proportion of urban area and decreasing proportion of forests. We also found that P. icarus is a low to moderate disperser relative to other butterflies. Our results suggest that P. icarus may become widespread in disturbed and urban areas across Canada, but that further investigation into additional potential range-constraining factors (e.g., microclimate), especially larval preferences, and modelling of the trajectory of P. icarus range expansion is needed.

Pervasive cropland in protected areas highlight trade-offs between conservation and food security.

Global cropland expansion over the last century caused widespread habitat loss and degradation. Establishment of protected areas aims to counteract the loss of habitats and to slow species extinctions. However, many protected areas also include high levels of habitat disturbance and conversion for uses such as cropland. Understanding where and why this occurs may realign conservation priorities and inform protected area policy in light of competing priorities such as food security. Here, we use our global synthesis cropland dataset to quantify cropland in protected areas globally and assess their relationship to conservation aims and socio-environmental context. We estimate that cropland occupies 1.4 million km2 or 6% of global protected area. Cropland occurs across all protected area management types, with 22% occurring in strictly protected areas. Cropland inside protected areas is more prevalent in countries with higher population density, lower income inequality, and with higher agricultural suitability of protected lands. While this phenomenon is dominant in midnorthern latitudes, areas of cropland in protected areas of the tropics and subtropics may present greater trade-offs due to higher levels of both biodiversity and food insecurity. Although area-based targets are prominent in biodiversity goal-setting, our results show that they can mask persistent anthropogenic land uses detrimental to native ecosystem conservation. To ensure the long-term efficacy of protected areas, post-2020 goal setting must link aims for biodiversity and human health and improve monitoring of conservation outcomes in cropland-impacted protected areas.

Habitat disturbance modifies dominance, coexistence, and competitive interactions in tropical ant communities

1. Interspecific competition is a major structuring principle in ecological communities. Despite their prevalence, the outcome of competitive interactions is hard to predict, highly context‐dependent, and multiple factors can modulate such interactions.2. We tested predictions concerning how competitive interactions are modified by anthropogenic habitat disturbance in ground‐foraging ant assemblages inhabiting fragmented Inter‐Andean tropical dry forests in southwestern Colombia, and investigated ant assemblages recruiting to baits in 10 forest fragments exposed to varying level of human disturbance.3. Specifically, we evaluated how different components of competitive interactions (patterns of species co‐occurrence, resource partitioning, numerical dominance, and interspecific trade‐offs between discovery and dominance competition) varied with level of habitat disturbance in a human‐dominated ecosystem.4. Multiple lines of evidence suggest that the role of competitive interactions in structuring ground‐foraging ant communities at baits varied with respect to habitat disturbance. As disturbance increased, community structure was more likely to exhibit random co‐occurrence patterns, higher levels of monopolization of food resources by dominant ants, and disproportionate dominance of a single species, the little fire ant (Wasmannia auropunctata). At a regional scale, we found evidence for a trade‐off between dominance and discovery abilities of the 15 most common species at baits.5. Together, these results suggest that human disturbance modifies the outcome of competitive interactions in ground‐foraging ant assemblages and may promote dominant species that reduce diversity and coexistence in tropical ecosystems.

Lower levels of human disturbance correspond with longer-term persistence of Endangered Green Peafowl Pavo muticus populations

SummaryGalliformes are one of the most threatened groups of birds in South-East Asia, with 27% of the species threatened with extinction. Long term population viability and extinction probability studies, at different levels of threat and management, are lacking due to weak life history data. This study aimed to define the long-term viability and extinction risk of two populations of the endangered Green Peafowl Pavo muticus, facing different threat and protection levels, using Bayesian Population Viability Analysis (BPVA), which requires less data than traditional methods. The results showed an increasing trend in the Green Peafowl population in HuaiKhaKhaeng Wildlife Sanctuary (western Thailand), with a high protection level and low disturbance and high probability of assuring persistence for the next 100 years. By contrast, the population in YokDon National Park (south-central Vietnam), with a high habitat disturbance level and significant hunting pressure, is predicted to decline and has a high probability (99%) of extinction by 2097. Also, the BPVA showed minimum viable population (MVP) estimates of 250 and 450 calling males for the HuaiKhaKhaeng and YokDon populations respectively, assuring high probabilities of long-term persistence if the minimum numbers of males are available. The population size of 219 calling males at YokDon during the 2013 survey is lower than the MVP threshold of 450 calling males, which suggests the species has a low probability of long-term persistence in the area. Despite limited life history and population data, BPVA predicted the future of this population under site-specific conditions, and the results could be used to promote better management and population restoration.

Assessing the function of geophagy in a Malagasy rain forest lemur

AbstractGeophagy has been observed in nearly every long‐term study of folivorous primates. Yet despite frequent observations of this behavior, conclusive explanations for soil consumption remain ambiguous. This study tests the most frequently proposed hypotheses for geophagy using data collected on the geophagic behavior of the Milne‐Edwards’ sifaka (Propithecus edwardsi) living in two forests with varying levels of disturbance within Ranomafana National Park, Madagascar. Field data were collected from December 2002 to November 2003, during which time soil samples were collected for mineral analyses from 102 sites selected for geophagy and 42 control sites at which no geophagy was recorded. Results indicate that control soils differ significantly between the two study sites and that this difference is primarily attributable to varying levels of habitat disturbance. The frequency of soil consumption also does not vary significantly by sex or between logged and unlogged habitats. Soil consumption significantly correlated with fruit/seed consumption overall, but to a lesser degree in logged compared with unlogged sites. Clay minerals found in soils likely prevent absorption of dietary toxins in the gut and/or may mediate gut pH. This provides strong evidence for the protection hypothesis for geophagy, which may be especially important in areas where logging, or other forms of habitat disturbance, has been experienced.Abstract in French is available with online material.

The first comprehensive survey of habitat suitability and population size for the endangered Grande Comoro Scops Owl (Otus pauliani): implications for its conservation

The Grande Comoro Scops Owl (Otus pauliani) is an endangered, rare and elusive owl species restricted to the Karthala forest, Grande Comore. This scops owl species is listed among the most threatened animals of the Comoro archipelago. The species is subjected to strong anthropogenic pressures causing a high rate of habitat loss. Little is known about the species’ population size, habitat suitability and geographic distribution, making the establishment of relevant conservation strategies difficult. In this study we assessed the population density and abundance of the species using the distance sampling approach through (1) the conventional distance sampling method (CDS), and (2) density surface modeling (DSM). Based on DSM, we applied a species distribution modeling method to investigate habitat suitability and geographic distribution of the species to close this knowledge gap. Average population density was estimated to be ca. 27 individuals km−2. We estimated a global population size of 3452 individuals. Our DSM suggested that the Grande Comoro Scops Owl has a very limited distribution (133 km2), restricted to high elevations in Grande Comore’s remaining natural forests (between 800 and 2000 m altitude). However, the currently high level of habitat disturbance and conversion of natural forest into agricultural land could render the species vulnerable to extinction. To ensure the viability of the species and the biodiversity of the Karthala forest, we suggest (1) restoring forest and securing corridors in the Karthala remnant forest; (2) avoiding the conversion of secondary forest into agricultural land, and using existing agroforestry for plantation development; (3) involving a broad community of local individuals and entities in their conservation and management.

Flexible nest‐site selection under anthropogenic habitat change in an Afrotropical understorey insectivore

Human activities impact upon natural habitats used by birds for breeding and foraging, and lead to changes in the composition and spatial distribution of predator communities, mainly through loss, fragmentation and disturbance of formerly pristine habitat. Yet possible fitness consequences of such changes through impacts on bird nest‐site selection remain poorly known. Here we study nest‐site selection and reproductive success of Placid Greenbuls Phyllastrephus placidus in the Taita Hills, southeast Kenya. We show that habitat features associated with nest‐site selection by this insectivorous, open‐cup‐nesting bird species vary among forest fragments that are exposed to different levels of habitat disturbance. Such differences in sites selected for breeding result from a plastic response to fragment‐specific conditions or may be driven by fragment‐specific variation in the distribution and availability of certain habitat features. Given the overall high nest predation rates in our study area, we expected variation in nest‐site selection to correlate with reproductive success and nestling condition, but detected no such relationship. Because predator density and nest predation rates may vary strongly in space and time, a better understanding of spatio‐temporal variation in predator communities is needed to assess the possible adaptive value of nest‐site selection strategies for reducing the high predation rates that are typical for this and many other open‐cup‐nesting tropical passerines.

Landscape structure and composition define the body condition of dung beetles (Coleoptera: Scarabaeinae) in a fragmented tropical rainforest

Environmental disturbance generates changes in local abiotic and biotic conditions, which affect the physiological condition of the organisms. However, most of the studies dealing with environmental disturbance have focused only on species diversity, and often ignore the species’ health to evaluate habitat quality. Recently, through tools that evaluate the body condition of individuals, some studies have demonstrated that it is possible to know how species respond to environmental changes. In this study, we evaluated the effect of local and landscape parameters on different indicators of body condition and abundance of three dung beetle species in a fragmented Tropical rainforest in Mexico. We measured beetle’s body size and three indicators of physiological condition (body dry mass, lipid and muscle mass) in 15 sites with different vegetation configuration. In general, abundance, body size and physiological condition of all species were sensitive to different landscape features. Onthophagus rhinolophus, a species typically found in conserved forest, unexpectedly showed a positive relation of body condition with landscape diversity and amount of edge, and the presence of altered sites remnants favored its body dry mass, muscle mass and body size. Nevertheless, Onthophagus batesi and Canthon cyanellus, mostly found in disturbed areas, exhibited better body condition when there were conserved habitats nearby. Therefore, we showed that O. rhinolophus is a sensitive species supporting reduced levels of habitat disturbance, while O. batesi and C. cyanellus are tolerant species that need conserved forests nearby. We highlight the importance of understanding the effect of environmental disturbance on the species’ body condition in order to maintain not only abundant, but also healthy populations of wild animals in fragmented forests.

The role of protected area zoning in invasive plant management

As anthropogenic pressure on the landscape increases, invasive alien species (IAS) pose a growing threat to areas designed to protect high biodiversity habitats. In order to assess the present danger of IAS spread, we examined 23 Czech sites of community importance (SCI) within Natura 2000 protected areas (PA) over 2015 and mapped the occurrence of four IAS: Solidago spp. (goldenrod), Impatiens glandulifera (Himalayan balsam), Heracleum mantegazzianum (giant hogweed) and Fallopia spp. (Japanese knotweed). The model areas were divided into five monitoring zones, graded by conservation importance and habitat disturbance level (core area [A], broader core area [B], semi-natural habitat [C], anthropogenically affected habitat [D], anthropogenically degraded habitat [E]). Despite a high number of IAS occurrences (3222 localities), habitats of European importance (zone A) showed a relatively low level of invasion (< 0.3% total area). Highest IAS occurrence number was in SCI border areas and disturbed habitats (zones C and E). There was a significant positive correlation between level of invasion inside and outside SCIs, related to human activities such as logging and urbanisation. A strong effect for watercourse vicinity was noted for the occurrence of I. glandulifera and Fallopia spp.; but not for H. mantegazzianum and Solidago spp. A stratified management approach, employing zones delimitation to assess what threat pose IAS to the PA objects of conservation, can be useful to prioritize control measures in IAS local action plans.

Contrasting impacts of land‐use change on phylogenetic and functional diversity of tropical forest birds

Abstract Biodiversity conservation strategies increasingly target maintaining evolutionary history and the resilience of ecosystem function, not just species richness (SR). This has led to the emergence of two metrics commonly proposed as tools for decision making: phylogenetic diversity (PD) and functional diversity (FD). Yet, the extent to which they are interchangeable remains poorly understood. We explore shifts in and relationships between FD and PD of bird communities across a disturbance gradient in Borneo, from old‐growth tropical forest to oil palm plantation. We show a marked decline in PD, and an increase in phylogenetic mean nearest taxon distance from forest to oil palm, in line with declining SR across the gradient. However, phylogenetic mean pairwise distance is constrained by forest logging more than by conversion to oil palm, taking account of SR. The decline in FD across the gradient is less severe than in PD, with all metrics indicating relatively high trait diversity in oil palm despite low SR, although functional redundancy is much reduced. Accounting for SR, levels of functional over‐ or under‐dispersion of bird communities are strongly coupled to habitat disturbance level rather than to any equivalent phylogenetic metric. Policy implications. We suggest that while phylogenetic diversity (PD) is an improvement on species richness as a proxy for functional diversity (FD), conservation decisions based on phylogenetic diversity alone cannot reliably safeguard maximal functional diversity. Thus, phylogenetic diversity and functional diversity are related but still complementary. Priority setting exercises should use these metrics in combination to identify conservation targets.

Species Richness and Distribution of Primates in Disturbed and Converted Forest Landscapes in Northern Borneo

Knowledge of fundamental aspects of ecology such as species richness and distribution, and the factors affecting them, is increasingly used to identify priority areas for conservation and to effectively manage threatened species. We investigated the species richness and distribution pattern of nonhuman primate communities inhabiting 10 sampling sites in four different habitat classes corresponding to increasing habitat disturbance level, that is, old growth forest, twice logged forest, repeatedly logged forest, and oil palm plantation, in and around Kalabakan Forest Reserve, in central Sabah, Malaysian Borneo. By using direct and indirect survey methods, we confirmed the existence of 9 out of the total 10 primate species, found in Sabah, within the surveyed areas. Based on the monthly number of primate species detected, our results indicated a general trend of decreasing primate species richness with increasing habitat disturbance level. However, the response within the disturbed forest sites showed some variations with some sites in repeatedly logged forest displaying comparable primate species number to that of the undisturbed forest sites. We also found that within the forest habitats, tree density is a good predictor of the richness of the primate community with a positive effect. Hence, tree density may be a key indicator for evaluating primate communities in forest habitats. Overall, the results of our study suggest that although not equivalent to areas of undisturbed forest, degraded forests—including those that have been repeatedly logged—are still valuable for primate conservation. In contrast, oil palm plantations have mainly negative effects on the primate community.

Effects of Fragment and Vegetation Structure on the Population Abundance of Ateles hybridus, Alouatta seniculus and Cebus albifrons in Magdalena Valley, Colombia

Many primate species currently subsist in fragmented and anthropogenically disturbed habitats. Different threats arise depending on the species' life history strategy, dietary requirements and habitat preference. Additionally, anthropogenic disturbance is far from uniform and may affect individual forest fragments in a single landscape in differing ways. We studied the effects of fragmentation on three species of diurnal primate, Cebus albifrons, Alouatta seniculus and Ateles hybridus, in Magdalena Valley, Colombia. We tested the assumption that generalist species are more resilient than specialist species to habitat degradation by examining the fragments' vegetation and spatial structure and how these affected primate presence and abundance patterns. We found C. albifrons, a generalist, to be the most abundant species in 9 of 10 forest fragments, regardless of the level of habitat disturbance. A. hybridus, a large-bodied primate with a specialist diet, was either absent or low in abundance in fragments that had experienced recent disturbances and was found only in higher-quality fragments, regardless of the fragment size. A. seniculus, a species considered to have a highly flexible diet and the ability to survive in degraded habitat, was found in intermediate abundances between those of Cebus spp. and Ateles spp., and was more frequently found in high-quality fragments.

Parallel declines in species and genetic diversity driven by anthropogenic disturbance: a multispecies approach in a French Atlantic dune system.

Numerous studies assess the correlation between genetic and species diversities, but the processes underlying the observed patterns have only received limited attention. For instance, varying levels of habitat disturbance across a region may locally reduce both diversities due to extinctions, and increased genetic drift during population bottlenecks and founder events. We investigated the regional distribution of genetic and species diversities of a coastal sand dune plant community along 240 kilometers of coastline with the aim to test for a correlation between the two diversity levels. We further quantify and tease apart the respective contributions of natural and anthropogenic disturbance factors to the observed patterns. We detected significant positive correlation between both variables. We further revealed a negative impact of urbanization: Sites with a high amount of recreational infrastructure within 10km coastline had significantly lowered genetic and species diversities. On the other hand, a measure of natural habitat disturbance had no effect. This study shows that parallel variation of genetic and species diversities across a region can be traced back to human landscape alteration, provides arguments for a more resolute dune protection, and may help to design priority conservation areas.

Species Composition of Tropical Understory Birds in Threatened East African Coastal Forests Based on Capture Data

The East African coastal forests are subject of haphazard modification following anthropogenic pressures including tree cutting and clearing for agriculture. These activities, which are leading cause of habitat disturbance and species loss, are the major challenge in the management of sensitive wildlife species such as forest understory birds. This study investigated species composition of understory birds in the coastal forests of northeastern Tanzania to generate information for the management of the landscape and biodiversity in the area. Using mist nets, birds were trapped from core and edge habitats of representative forest patches. Trapped birds were classified to species level and categorized into bird guilds based on their levels of forest dependence. It was found out that species richness was influenced by forest patch size rather than level of habitat disturbance. Edge habitat was also found to be important in hosting higher number of forest understory birds, especially generalists—but this should be treated with caution because following habitat destruction that is ongoing in the study area, there is a danger of generalist wiping out specialist species due to competitive exclusion. Strict control measures to stop illegal tree cutting and agricultural activities near the forests were recommended for sustainable conservation of the understory birds in the forests.

Habitat disturbance effects on the physiological stress response in resident Kenyan white-bearded wildebeest (Connochaetes taurinus)

Regarded as a keystone species, white-bearded wildebeest (Connochaetes taurinus) are found across the grassland savannahs of eastern Africa. Over the past 40years, however, many local populations have become threatened with extinction. This is the first study connecting fecal glucocorticoid metabolites (i.e., stress hormones) in wildebeest with landscape variables of natural and anthropogenic disturbance. Using a validated technique, fecal samples (n=168) were collected from wildebeest over a 3-month study period and across three different study areas in Kenya with varying degrees of disturbance. The stress of sampled populations was similar between study areas, with a seasonal decline in stress hormones found between dry and wet season data collection periods. We used an information-theoretic approach to rank models of fecal glucocorticoid metabolites. Our highest ranking model included an interaction between locally collected plant biomass and disturbance, the number of calves in a group, and ΔNDVI (change in Normalized Difference Vegetation Index). A strong positive effect related to biomass and disturbance suggested that tall/standing biomass and high levels of disturbance contribute to elevated levels of stress in wildebeest. A strong negative effect related to ΔNDVI was also observed, suggestive that new growth lowers average stress levels. Our research suggests that increased levels of habitat disturbance may have an adverse effect on wildebeest populations across the region when habitat conditions deteriorate. Wildebeest likely avoid areas of high anthropogenic disturbance which may indirectly lead to lowered fitness.

Discovery of a New, Disjunct Population of a Narrowly Distributed Salamander (Taricha rivularis) in California Presents Conservation Challenges

A newly discovered population of Red-bellied Newts (Taricha rivularis) in the Stevens Creek watershed in Santa Clara County, California, represents a significant southerly range extension of this species, by approximately 130 km from the nearest records in Sonoma County, California. To investigate the origin of this population we sequenced two mitochondrial genes (ND1, cytochrome b) and one nuclear exon (POMC) from the Santa Clara County population and from the main portion of the range including Sonoma, Mendocino, and Humboldt Counties. Phylogenetic relationships, historical demography, and genetic diversity were used to infer the origin of the newly discovered population and to elucidate the evolutionary history of the species. This species exhibits the lowest genetic diversity of any salamander in coastal California, and we infer unique signatures of population expansion not found in sympatrically occurring salamander species. The newly discovered population, characterized by a ubiquitous mtDNA haplotype found throughout the main range, is not genetically divergent. Although we were unable to determine whether the Santa Clara population is natural or introduced, we consider it to be of potential conservation significance and to warrant management protection. Although it may be unconventional to protect a population that is possibly introduced, this newly discovered population might be a critical assurance colony that will aid in the long-term persistence of this declining species. Because T. rivularis lacks genetic variation, has a small geographic range, and has experienced high levels of habitat disturbance, we recommend that it receive protection throughout its range.