Species Status Assessment Research Articles

Status of a Marginal Dugong (Dugong Dugon) Population in the Lagoon of Mayotte (Mozambique Channel), in the Western Indian Ocean

The dugong (Dugong dugon) is one of the most endangered mammal species in eastern Africa. Dugongs are exposed to many human-induced threats, such as by-catch in fishing gears and deliberate killing. In order to understand the conservation and management issues surrounding this species status assessments are needed. An assessment was conducted in Mayotte (Comoros, Mozambique Channel) in 2003 to determine the status and distribution of the dugong. Questionnaire surveys were carried out in August 2003 with local fishermen. Results of opportunistic sightings were collected from 1999 to 2005 (n=53), and aerial surveys were undertaken between July and November 2005. The three data sources provide historical and actual data on the status of the species. Dugongs were common in the lagoon before the 1980’s, and then declined significantly due to hunting pressure and by-catch in fishing nets. In the 2000’s, opportunistic sightings have been made regularly by recreational dive operators and microlight aircraft pilots. Recent sightings indicate calving in the lagoon of Mayotte, with several observations of mother-calf pairs. Measures to protect Mayotte’s marine biodiversity, such as establishing a network of Marine Protected Areas, banning fishing nets and developing pelagic fisheries is expected to help ensure the future survival of the dugong in this area.

An Objective Means of Species Status Assessment: Adapting the Delphi Technique

A status assessment for wildlife species is necessary for many states in the United States with the authority to list species as endangered and threatened. Status may confer legal protection or conservation priority within a state. The methods used to define species status vary across states, but most rely on subjective determinations made by a group of experts. We adapted the Delphi Technique, a systematic method of reaching consensus, to achieve greater objectivity in determining the relative endangerment or stability of a species' population. We used the method to determine the status of birds native to New Jersey by having experts choose a status, enumerate their confidence in it and justify their choice, on forms via mail. We compiled results and sent them back to all participants to review the information anonymously provided by others and vote again on each status based on this information, as well as their own experience and opinion. We continued this process for 4 rounds, reaching consensus on the status of 91% of 283 species in breeding and nonbreeding seasons. We used the results to assign legal status of bird species in the state. We present this as an appropriate technique to attain greater objectivity in species status assessment.

Designatable Units for Status Assessment of Endangered Species

Abstract: Species status assessment and the conservation of biological diversity may require defining units below the species level to portray probabilities of extinction accurately and to help set priorities for conservation efforts. What those units should be has been debated in the scientific literature largely in terms of evolutionarily significant units (ESUs), but this discourse has had little impact on government policy with regard to status assessment. As with species concepts, the variously proposed ESU concepts have not been resolvable into a single approach. The need for a practicable procedure to identify infraspecific entities for status assignment is the motivation behind employing designatable units (DUs). In aid of a policy to prevent elements of biodiversity from becoming extinct or extirpated, DUs are determined during the process of resolving a species' conservation status according to broadly applicable guidelines. The procedure asks whether putative DUs are distinguishable based on a reliably established taxonomy or a well‐corroborated phylogeny, compelling evidence of genetic distinction, range disjunction, and/or biogeographic distinction as long as extinction probabilities also differ. The language of the DU approach avoids wording that implies value judgments concerning evolutionary importance or significance. Because species conservation status assessment is not science but, rather, the use of science to further policy, DUs contribute to a precautionary approach to listing whereby status may be assessed even though knowledge of systematic relationships below the species level may be lacking or unresolved. The pragmatic approach of using DUs has been adopted by the Committee on the Status of Endangered Wildlife in Canada for status assessment of species under the Canadian Species at Risk Act.

Can landscape composition changes predict spatial and annual variation of little bustard male abundance?

We studied variables affecting spatial and inter-annual variations in presence/absence and abundance of little bustard (Tetrax tetrax) males in extensive cereal farmland in central Spain. Both variables were positively influenced by the percentage of arable surface and also by substrate heterogeneity. In addition, male abundance varied significantly between years and among sectors of the study area, even when taking into account variation in landscape variables. A significant interaction between year and sector showed that abundance variations did not follow a fixed pattern, meaning that interannual variation in male abundance among sectors cannot be predicted. We discuss potential alternatives to explain such variation, as well as the implications of our results for the species' population estimates, status assessment and conservation.

4 - The Use of Human Placental Lactogen in the Antepartum Monitoring of Pregnancy

Spatial synchrony—correlated abundance fluctuations among distinct populations—is associated with increased extinction risk but is not a component of widely-used extinction risk assessments (e.g., IUCN Red List, U.S. Fish and Wildlife Service's Species Status Assessment). Alongside traditional viability metrics (i.e., the number of populations, their spatial extent, the status of each population), consideration of spatial synchrony in these assessments may provide additional insight into extinction risk as well as the relative importance of intrinsic and extrinsic factors on population dynamics. We demonstrate a method for estimating abundance trends in populations of the endangered freshwater fish, the amber darter (Percina antesella), while simultaneously assessing empirical support for existence of spatial synchrony among its two populations in the Conasauga and Etowah rivers in Georgia, U.S.A. Our analysis was performed using multivariate autoregressive state-space (MARSS) models with annual sampling data from 1996 to 2018 at 16 sites distributed between the two rivers. Our results indicate that amber darter populations have declined substantially, with 9% annual losses in both the Conasauga and Etowah rivers, suggesting rangewide imperilment. Furthermore, model selection indicated little support for models with fully independent dynamics between rivers, which may compound overall extinction risk. This analysis demonstrates the utility of tools such as MARSS models for assessing spatial synchrony and long-term population trajectories of imperiled species, resulting in improved vulnerability assessments that do not assume independence among separate populations.