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Identifying connectivity patterns among remnant bird populations and their relationship with land use practices and subjacent habitat fragmentation is key for implementing appropriate management strategies for species conservation. The coastal thorn scrub forest and dune vegetation complex in the northern Yucatan Peninsula has been affected by coastal development. These human induced processes of land use change can affect the Yucatan Wren (Campylorhynchus yucatanicus), an endemic bird to this vegetation types with a narrow distribution. To identify possible anthropogenic barriers to connectivity of populations of C. yucatanicus, we collected 140 samples from 14 localities and used seven nuclear microsatellite loci to describe the current structure and genetic diversity of populations of C. yucatanicus. We explored the relationship between the genetic variability of populations and landscape structure through regression models. In addition, we described the relationship between genetic distance and landscape resistance. We found four genetic populations with Bayesian clustering methods. Human settlements and availability of adequate habitat limit the connectivity between sites due to ongoing land use changes. We suggest some management actions for conservation of this species, and we propose to change the IUCN threat category to "endangered" because of today the species has a more restricted distribution, small population, habitat degradation, loss of connectivity, and loss of genetic variability.

Predictive species distribution models and environmental niche evaluation have become useful techniques in conservation biogeography and are increasingly used as prediction tools to identify priority conservation areas for focal species. Multiple hypotheses and paradigms were proposed to explain the variation seen in geographical range sizes among species. Our hypothesis was that in a monophyletic group of 7 Campylorhynchus species, those with a broad climatic niche would persist over a wide geographic range while species with a narrow climatic niche, such as C. yucatanicus, would be restricted to a smaller geographic range. To test this hypothesis, we modeled potential distributions using the MaxEnt algorithm and estimated the climatic niche of 7 species included in the monophyletic group of Campylorhynchus (Troglodytidae). To compare the ecological niches of these 7 species, we plotted the occurrence density for each species with combinations of environmental conditions and then identified the first 2 components using a principal component analysis. In general, the most important variables predicting species presence were rainfall seasonality and minimum temperature during the coldest month. The climatic niches for these 7 species were relatively segregated throughout the environmental space. When compared with related species, C. yucatanicus had the narrowest niche width and lowest niche similarity and overlap index, which could explain the restricted distribution for this species. Given the restricted range of C. yucatanicus within the Yucatan Peninsula, the species is highly vulnerable to small disturbances, current local threats (e.g., habitat alterations due to urbanization), and global threats (e.g., climate change). We therefore recommend increased national and international protection for C. yucatanicus and that it be listed as globally threatened by the International Union for Conservation of Nature (IUCN). Received 22 June 2016. Accepted 9 June 2017.

Resumen La distribución geográfica y la calidad del hábitat son criterios fundamentales para evaluar el grado de riesgo de extinción y amenaza de las especies. Campylorhynchus yucatanicus es un ave endémica de la costa norte de la Península de Yucatán, México con distribución restringida a una estrecha franja de hábitat, entre los estados de Campeche y Yucatán. En la actualidad, la costa yucateca ha perdido más de la mitad de la vegetación de duna costera y otros hábitats se han modificado principalmente por falta de un plan de urbanización y mal aprovechamiento de los recursos naturales. Estos factores amenazan a C. yucatanicus, que está catalogada como una especie casi amenazada por la UICN y como una especie en peligro de extinción por la legislación mexicana, NOM-059-2010. En este estudio se modeló su distribución potencial utilizando 64 registros de presencia de variadas fuentes (1960 y 2009), un conjunto de variables climáticas y una capa de Índice de vegetación de diferencia normalizada (NDVI). Para evaluar el grado de conectividad del paisaje se empleó un mapa de tipos de vegetación y uso de suelo, distancia a los poblados y a las carreteras asfaltadas. El modelo de distribución potencial arrojó una distribución potencial de 2 711 km2 aproximadamente, 2 % del área total de la Península de Yucatán. De esta área, solo el 27 % está protegido con categoría de Reserva de la Biósfera y sólo el 10 % corresponde a áreas núcleo de conservación, con restricciones de uso de suelo y protección relativamente efectiva. Las poblaciones de la región de Ría Lagartos y del oeste de Celestún, parecen ser las más aisladas, teniendo en cuenta el modelo de conectividad del paisaje. La permeabilidad del paisaje entre fragmentos de vegetación de duna cerca de la costa es baja, principalmente por la distribución de las zonas urbanas. Los resultados pueden ser usados para establecer estrategias de manejo y sugieren que la especie se encuentra en un estado de conservación más delicado del que hasta ahora se había descrito por la UICN. Consideramos que C. yucatanicus debe tener categoría en peligro de la UICN según su distribución y la conectividad de paisaje actual. Abstract Geographic distribution and habitat quality are key criteria for assessing the degree of risk of species extinction threat. Campylorhynchusyucatanicus(Yucatán Wren, Troglodytidae) is an endemic bird of the Northern coast of the Yucatán Peninsula, Mexico, with a distribution restricted to a narrow strip of habitat, between Campeche and Yucatán states. Currently, the Yucatán coast has lost more than half of the coastal dune vegetation, and other habitats have been modified mainly because there is no urban development plan and the natural resources management is poor. These factors threaten C. yucatanicus, which is listed as a near threatened species by IUCN and as an endangered species by Mexican law NOM059-2010. In this paper, C. yucatanicus´s potential distribution was modeled using 64 presence records from several sources (1960 y 2009), a set of climate variables, and a vegetation index layer of normalized difference (NDVI). To assess the degree of landscape connectivity we used a map of vegetation types and land use, distance to villages and paved roads. The potential distribution model showed an area of approximately 2 711 km2, which is 2 % of the total area of the Yucatán Peninsula distribution. In this area, only 27 % is protected by Biosphere Reserve category and only 10 % belong to core conservation areas, with land use restrictions and relatively effective protection. The populations from Ría Lagartos and Western Celestún regions appear to be the most isolated following the model of landscape connectivity. Landscape permeability among fragments of dune vegetation near the coast is low, mainly due to the distribution of urban areas. These results can be used to establish management strategies, and show that the species is in more delicate conditions than what it has been described by IUCN. We consider that C. yucatanicus should be given endangered category by IUCN, because of their distribution and the context of the current landscape connectivity.

Resumen El flamenco caribeño (Phoenicopterus ruber) en México se distribuye en todo el complejo de lagunas dentro de los humedales costeros de la Península de Yucatán y se ha observado una cierta tendencia a un uso diferencial de las áreas entre los juveniles y adultos en las diferentes etapas de su ciclo de vida, según las estaciones del año. El objetivo de este estudio fue determinar las áreas más importantes donde se distribuyen espacialmente los flamencos en los humedales de Yucatán, México y sus variaciones temporales según la edad y las diferentes etapas de su ciclo de vida. Se utilizaron registros de individuos anillados que se han avistado durante el período 2010-2015. Se identificaron las áreas con el mayor número de individuos según la estación y la temporada. Se registraron flamencos en 39 áreas diferentes, de 43 muestreadas. En general, los sitios con el mayor número de registros fueron: La Angostura y Punta Mecoh. Tanto para los juveniles como para los adultos, las áreas con mayores porcentajes de ocupación fueron diferentes por edades entre las diferentes etapas del ciclo de vida y las estaciones del año. Charca Salinera Chel e Isla La Angostura fueron áreas en las que se registraron flamencos anillados de casi todas las edades. Aunque se siguen destacando como zonas importantes para la especie, ya descritas con anterioridad (Celestún, Ría Lagartos), aparecen nuevos sitios que albergan un número considerable de la población en algún momento de su ciclo de vida (e. g. Humedal Progreso. Salamandra, Laguna Rosada; Xcambo). A estos nuevos sitios se les debe prestar más atención y se recomiendan medidas de seguridad y protección importantes para todos ellos. Es necesario buscar nuevas fuentes de apoyo para realizar estudios que determinen el estado de las poblaciones de flamencos en áreas de difícil acceso de las que se tiene muy poca información. Abstract The Caribbean Flamingo (Phoenicopterus ruber) in Mexico is distributed throughout the complex of lagoons in coastal wetlands of the Yucatan Peninsula. The species shows a tendency toward differential use of areas between juveniles and adults at different stages of their life cycle, and in different seasons. The aim of this study was to determine the most important areas where flamingos are distributed in Yucatan wetlands, and to describe temporal variations according to age and stages of their life cycle. For this, we used the records of ringed individuals sighted during the period 2010-2015. The areas with the largest numbers of individuals, by stage and season, were identified. Flamingos were recorded in 39 different areas of 43 sampled. In general, the sites with the largest number of records were Isla La Angostura and Punta Mecoh. To both juveniles and adults, areas with higher occupancy rates differed by age between the different stages of the life cycle and seasons. In the Charca Salinera Chel and Isla La Angostura ringed flamingos of almost all ages were recorded. Although already described areas (Celestún, Ría Lagartos) are certainly important, new sites hosting considerable populations at some stage of this species life cycle were detected (e.g. Humedal Progreso; Salamandra, Laguna Rosada; Xcambo). These new sites should be given more attention and important security measures and protection are recommended to all of them. It is necessary to seek new support sources for studies that determine the flamingo population’s status in difficult access areas for which little information is available.