Occupancy and detectability of a critically threatened lizard endemic from sandy coastal plains areas of Rio de Janeiro State, Brazil

Liolaemus lutzae is a small liolaemid lizard critically endangered and restricted to coastal restinga (salty sand dune habitats covered by herbaceous and shrubby vegetation by seaside) habitats of the state of Rio de Janeiro in Brazil. This lizard has been predicted to be extinct by 2080. We studied some of the environmental factors that influence occupancy by the species and detectability by the observer, in addition to investigating which populations remain occupying the areas along its original geographical distribution. We sampled 25 different beach habitats of restinga areas in the state, by 100-meter replicates of linear transects. The estimated probability of occupancy was 69% (0.69 +/- 0.05), and the estimated detectability was 50% (0.50 +/- 0.03). The detection model with the best fit contained only the air temperature variable. Occupancy was best described by four variables: number of disturbance sources on the transect, vegetation cover in a 50-meter buffer, exposed sand cover substrate in a 20-meter buffer, and built-up area cover in a 50-meter buffer. No observations of L. lutzae were made in eight of the 25 restinga areas sampled along the original distribution of the lizard. In seven of these areas, the species had its populations extirpated many years ago, based on the 2007/2008 monitoring data. Conversely, in one area where the species was frequently observed during field surveys and different ecological studies on the species made in last decade, it was not recorded in the present study, indicating a possible recent population extirpation. We recommend that conservation measures be urgently implemented to mitigate anthropogenic impacts on the areas of the remaining populations of this lizard throughout its range, especially preserving the structure and functions of the remaining vegetation of beach habitat along restinga areas. Liolaemus lutzae e um pequeno lagarto liolaemideo criticamente ameacado e restrito aos habitats de restinga (habitats de dunas costeiras cobertas por vegetacao herbacea e arbustiva) do estado do Rio de Janeiro no Brasil. Este lagarto tem previsoes de ser extinto ate 2080, caso medidas nao sejam tomadas. Estudamos alguns dos fatores ambientais que influenciam a ocupacao pela especie e a detectabilidade pelo observador, alem de investigar quais populacoes deste lagarto permanecem ocupando as areas ao longo de sua distribuicao geografica original. Foram amostrados 25 diferentes habitats de praia em areas de restinga do estado, por meio de transectos lineares de 100 metros. A probabilidade estimada de ocupacao foi de 69% (0,69 +/- 0,05) e a detectabilidade estimada foi de 50% (0,50 +/- 0,03). O modelo de deteccao mais ajustado continha apenas a variavel temperatura do ar. A ocupacao foi melhor descrita por quatro variaveis: numero de fontes de perturbacao no transecto, cobertura vegetal em um buffer de 50 metros, cobertura de areia exposta em um buffer de 20 metros e cobertura de area construida em um buffer de 50 metros. Das 25 restingas amostradas, em oito delas nao encontramos individuos de L. lutzae. Em sete dessas areas a especie teve suas populacoes extirpadas ha muitos anos, com base nos dados de monitoramento de 2007/2008. Por outro lado, em uma area onde a especie foi frequentemente observada durante diferentes estudos ecologicos realizados ao longo da ultima decada, ela nao foi registrada, indicando uma possivel extirpacao populacional recente. Recomendamos que, num curto espaco de tempo, sejam implementadas medidas de conservacao para mitigar os impactos antropicos nas areas das populacoes remanescentes deste lagarto em toda a sua distribuicao, preservando especialmente a estrutura e funcoes da vegetacao remanescente do habitat de praia ao longo das areas de restinga. We studied factors that influence occupancy and detectability of a critically endangered lizard restricted to beach habitats of Rio de Janeiro, investigating the remaining populations along its distribution.image