Diet of Crotalus enyo (Serpentes: viperidae) from the Baja California Cape Region, Mexico

Crotalus enyo is a rattlesnake endemic to Baja California peninsula, Mexico. The natural history of this species is poorly known, so the goal of this study was to determine the diet of C. enyo in the Cape Region, an area with different conditions than the rest of the peninsula. We analyzed the stomach contents of 24 specimens obtained during 2010-2013, and identified the ingested prey. The diet of C. enyo consists of rodents (83.34%) and lizards (16.66%), although presents a diverse diet, the data suggest C. enyo is a specialist predator at Cape Region. We didn’t find differences in diet composition between sexes, site of capture, or season. This study documents three new prey items in the diet of C. enyo: the Orange-Throated Whiptail (Aspidocelis hyperythra), the Cape Spiny-Tailed Iguana (Ctenosaura hemilopha) and Hunsaker’s Spiny Lizard (Sceloporus hunsakerii)

JUVENILE RECRUITMENT, EARLY GROWTH, AND MORPHOLOGICAL VARIATION IN THE ENDANGERED SANTA CATALINA ISLAND RATTLESNAKE, CROTALUS CATALINENSIS

Life-history information constitutes the raw data for building population models used in species conservation. We provide life-history data for the endangered Santa Catalina Island Rattlesnake, Crotalus catalinensis. We use data from 277 observations of C. catalinensis made between 2002 and 2011 on the island. Mean snout-vent length (SVL) of adult C. catalinensis was 643 mm for males and 631 mm for females; the difference was not significant. The degree of sexual size dimorphism (SSD; using SVL) was -0.02. However, sexes were dimorphic in total length ( SVL + tail length), relative tail length, and stoutness. Juvenile recruitment occurs during late-summer. In their first year of life, juveniles seem to grow at a rate of about 1.7 cm/mo. Females seem to become mature around 570 mm SVL, probably in the year when they become 2 y old. Scattered literature data corroborates the time of juvenile recruitment described herein. Growth in C. catalinensis seems to be slower than that of C. ruber, its sister taxa, but similar to other rattlesnakes.Comision Nacional para el Conocimiento y Uso de la Biodiversidad (CONABIO)Comision Nacional para el Conocimiento y Uso de la Biodiversidad (CONABIO)Secretaria del Medio Ambiente y Recursos Naturales (SEMARNAT)Secretaria del Medio Ambiente y Recursos Naturales (SEMARNAT)Consejo Nacional de Ciencia y Tecnologia (CONACyT) [FB1484/HK051, SEMARNAT-CONACyT-2002-C01-0584]Consejo Nacional de Ciencia y Tecnologia (CONACYT)Fundacao de Amparo a Pesquisa do Estado de Sao Paulo (FAPESP) [2010/50146-3]Fundacao de Amparo a Pesquisa do Estado de Sao Paulo (FAPESP

Vaccination strategy on a geographic network

We considered a mathematical model describing the propagation of an epidemic on a geographical network. The initial growth rate of the disease is the maximal eigenvalue of the epidemic matrix formed by the susceptibles and the graph Laplacian representing the mobility. We use matrix perturbation theory to analyze the epidemic matrix and define a vaccination strategy, assuming the vaccination reduces the susceptibles. When the mobility is small compared to the local disease dynamics, it is best to vaccinate the vertex of least degree and not vaccinate neighboring vertices. Then the epidemic grows on the vertex corresponding to the largest eigenvalue. When the mobility is comparable to the local disease dynamics, the most efficient strategy is to vaccinate the whole network because the disease grows uniformly. However, if only a few vertices can be vaccinated then which ones do we choose? We answer this question, and show that it is most efficient to vaccinate along the eigenvector corresponding to the largest eigenvalue of the Laplacian. We illustrate these general results on a 7 vertex graph, a grid, and a realistic example of the french rail network

Impacto de la erradicación del gato (felis catus), en dos roedores endémicos de la Isla Coronados, Golfo de California, México

It is not known when the domestic cat (Felis catus) was introduced to Coronados Island or when they reached it. Their impact on endemic rodents has been evident, rodents constitute 70% of their diet and they are putting in danger the survival of rodents. Cat eradication was initiated in November 1998 and finished in March 1999. In order to identify the eventual response of rodents to the absence of cats, a monitoring program of two resident rodents Peromyscus pseudocrinitus and Chaetodipus spinatus pullus, was undertaken before, during, and after the eradication program. The monitoring program finished in 2005. Initially an increase in rodent populations occurred followed by fluctuations in the population. Despite the fact that there was no evident benefit derived from the eradication program, it is clear that their removal was positive, since their presence represented a potential risk to endemic rodent species on the island, which could be exterminated during critical periods if feral cat continued in the island.Se desconoce el año en que fue introducido el gato (Felis catus) a la Isla Coronados, así como el número máximo que alcanzó su población, sin embargo, su efecto sobre los roedores nativos fue evidente, ya que los integró a su dieta, constituyendo el 70% de la misma, poniendo en peligro su supervivencia. El programa de erradicación de gatos fue iniciado en noviembre de 1998 hasta la remoción de todos los individuos en marzo del 1999. Se llevó a cabo el monitoreo de las poblaciones de Peromyscus pseudocrinitus y Chaetodipus spinatus pullus antes, durante y después del programa de erradicación, concluyendo el monitoreo en el año 2005, con el fin de identificar la eventual respuesta de los roedores a la ausencia de gatos. A corto plazo se presentó un incremento en las poblaciones de roedores, sin embargo, a largo plazo, estas fluctuaron de acuerdo a la disponibilidad de alimento y a las condiciones climáticas prevalecientes. A pesar de que no hubo evidencia numérica en las poblaciones de roedores, del beneficio de la erradicación de gatos, es claro que su remoción fue positiva, ya que su presencia representaba un riesgo potencial para las especies presentes, las cuales podrían ser extinguidas durante períodos críticos si los gatos continuaran presentes en la isla

Dieta y ámbito hogareño del gato feral, Felis catus (Carnivora: Felidae) en la Isla Socorro, Archipiélago de Revillagigedo, México

Socorro is an oceanic island rich in biodiversity and endemisms. However, the island has been threatened by feral cats since 1957. The diet of this predator, determined through the analysis of stomach contents of 79 cats, consisted mostly of house mice (Mus musculus, 22.16%), endemic lizards (Urosaurus auriculatus, 15.09%), anthropogenic rubbish (15.09%), and insects (Orthoptera, 13.20%). The home range of the feral cat was identified through telemetry using four individuals with GPS/VHF radio-collars. The three males had a much larger average home range of 219.10 ha, as compared with 118.86 ha of the female. Knowing the home range of the Socorro Island feral cat is critical for the successful eradication of the island's invasive population. Thanks to this information, it is possible to calculate the trapping effort and the amount of bait needed per unit area to successfully carry out the ongoing eradication, contributing to the conservation of global biodiversity.Isla Socorro es una isla oceánica rica en biodiversidad y endemismos. Sin embargo, la isla ha sido impactada por el gato asilvestrado desde 1957. A través del análisis del contenido estomacal de 79 gatos se determinó la dieta de este depredador, la cual está constituida mayormente por el ratón doméstico (Mus musculus, 22.16%), la lagartija endémica (Urosaurus auriculatus, 15.09%), residuos antropogénicos (15.09%), e insectos (Orthoptera, 13.20%). Se identificó el ámbito hogareño de los gatos a través de telemetría, utilizando cuatro individuos con radio-collares GPS/VHF. El ámbito hogareño de los machos resultó de 219.10 ha en promedio, mucho mayor que el de las hembras que fue de 118.86 ha. Conocer el ámbito hogareño del gato asilvestrado de Isla Socorro es clave para la erradicación exitosa de la población de la isla. Gracias a esta información se ha podido calcular el esfuerzo de trampeo o la cantidad de carnada que deben ser empleadas por unidad de área durante la erradicación en curso, que es relevante para la conservación de la biodiversidad global

Modelling potential distribution of the endemic ringtail (Bassariscus astutus saxicola) on an island of the Gulf of California

Objective: Analyze the topography of the island with a digital elevation model (DEM) at 30 m spatial resolution and generate the first distribution model for an endemic carnivore from the islands of the Gulf of California. Design/Methodology/Approach: This study employed the Maxent species distribution model to find the distribution of the ringtail in its habitat on Espíritu Santo Island. In 2015–2016, through four surveys, ringtails were trapped in eight glens on the west of the island. A total of 74 individuals were captured, with nine recaptures. Results: The variables with the greatest contributions to the models were elevation, contributing 71.6%; heat load index 15% and ruggedness 11.8%. The model predicts > 0.5 probabilities of presence of this carnivore in 3,018 hectares of the island. We obtained a high AUC value (0.928), which indicates that the model is accurate, and subsequently confirmed it with a value of pAUC = 1.917. Study Limitations/Implications: The habitat of the ringtail (Bassariscus astutus saxicola) was little known mainly because it is an endemic species. And there was not a published article that will show its distribution within the island. Conclusions: This model shows that topographic variables are useful to explain the potential distribution of the ringtail, mainly because the topography is related to sites that can offer thermal refuge, abundance of food, and escape routes from predators, among other features.Objetivo: Analizar la topografía de la isla mediante modelos digitales de elevación (DEM) con a 30 m de resolución espacial y generar el primer modelo de distribución potencial para un carnívoro endémico de las islas del Golfo de California. Diseño / Metodología / Enfoque: En este estudio se empleó el software Maxent para encontrar la distribución potencial del babisuri en la Isla Espíritu Santo. Los muestreos se realizaron en 2015–2016, los babisuris se muestrearon en ocho bahias en el oeste de la isla. Se capturaron un total de 74 individuos, con nueve recapturas. Resultados: Las variables con mayores aportes a los modelos fueron elevación, aportando 71.6%; índice de carga de calor el 15% y la rugosidad del 11.8%. El modelo predice> 0.5 probabilidades de presencia de este carnívoro en 3.018 hectáreas de la isla. Obtuvimos un valor alto de AUC (0.928), lo que indica que el modelo es exacto, y posteriormente lo confirmamos con un valor de pAUC = 1,917. Limitaciones / Implicaciones del estudio: El hábitat del babisuri (Bassariscus astutus saxicola) era poco conocido principalmente porque es una especie endémica. Y no existe un artículo publicado que muestre su distribución dentro de la isla. Conclusiones: Este modelo muestra que las variables topográficas son útiles para explicar la distribución potencial del babisuri, principalmente porque la topografía está relacionada con sitios que pueden ofrecer refugio termal, abundancia de alimento y rutas de escape de depredadores, entre otras características

The MUSIC of Galaxy Clusters I: Baryon properties and Scaling Relations of the thermal Sunyaev-Zel'dovich Effect

We introduce the Marenostrum-MultiDark SImulations of galaxy Clusters (MUSIC) Dataset, one of the largest sample of hydrodynamically simulated galaxy clusters with more than 500 clusters and 2000 groups. The objects have been selected from two large N-body simulations and have been resimulated at high resolution using SPH together with relevant physical processes (cooling, UV photoionization, star formation and different feedback processes). We focus on the analysis of the baryon content (gas and star) of clusters in the MUSIC dataset both as a function of aperture radius and redshift. The results from our simulations are compared with the most recent observational estimates of the gas fraction in galaxy clusters at different overdensity radii. When the effects of cooling and stellar feedbacks are included, the MUSIC clusters show a good agreement with the most recent observed gas fractions quoted in the literature. A clear dependence of the gas fractions with the total cluster mass is also evident. The impact of the aperture radius choice, when comparing integrated quantities at different redshifts, is tested: the standard definition of radius at a fixed overdensity with respect to critical density is compared with a definition based on the redshift dependent overdensity with respect to background density. We also present a detailed analysis of the scaling relations of the thermal SZ (Sunyaev Zel'dovich) Effect derived from MUSIC clusters. The integrated SZ brightness, Y, is related to the cluster total mass, M, as well as, the M-Y counterpart, more suitable for observational applications. Both laws are consistent with predictions from the self-similar model, showing a very low scatter. The effects of the gas fraction on the Y-M scaling and the presence of a possible redshift dependence on the Y-M scaling relation are also explored.Comment: 22 pages, 25 figures, accepted for pubblication by MNRA