Irene Ruvalcaba-Ortega

First nesting record of the long-eared owl (Asio otus) for Chihuahua, Mexico

Abstract We found two nests of the long-eared owl (Asio otus) in Reserva Ecológica el Uno, located in Janos municipality, Chihuahua, Mexico. Contents of nests were recorded, photographed, and monitored between 28 March and 10 June 2007. Nests were constructed on honey mesquites (Prosopis glandulosa) and contained three eggs and three nestlings, respectively. These nests represent the first confirmed breeding record for the state of Chihuahua and the second for Mexico (outside Baja California).

Winter diet of the long-eared owl Asio otus (Strigiformes: Strigidae) in the grasslands of Janos, Chihuahua, Mexico

BackgroundThe long-eared owl (Asio otus) has a Holarctic distribution, including much of North America. This nocturnal species is considered to be extremely secretive, and poorly known in the Great Plains of the United States and Canada, as well as to México, where no previous studies on its diet have been conducted.FindingsWe analyzed 120 pellets collected during January 2007 in roosts in a 2–3 m height mesquite scrub within a grassland area of Reserva Ecológica El Uno, located in the Natural Protected Area Janos. We registered and identified three orders, four families, eight genera and ten species of mammals and two orders and one family of insects. Winter diet is dominated by mammals, especially rodents in both frequency and biomass. Cricetidae and Perognathus flavus were the most frequent family and species, respectively. On the other hand, when analyzing biomass, Sigmodon species were dominant, achieving almost 70% of the consumed biomass. Levins standardized niche breath based on frequency was calculated as 0.40, while based on biomass was 0.38. Also, two previously unrecorded rodent species were identified as long-eared owl prey.ConclusionAlthough 18 different types of items were identified, the long-eared owl tends to be selective, with a single genera (Sigmodon) comprising almost 70% of its consumed biomass during winter. Perognathus flavus was also important in frequency (21%); however, it barely constitutes 2% of the consumed biomass.ResumenEl búho orejas largas es una especie Holártica, que se distribuye en gran parte de Norteamérica y que ha sido poco estudiada, especialmente en las Grandes Planicies de Estados Unidos y en México, donde no existe un estudio previo sobre su dieta invernal. Se colectaron y analizaron 120 egagrópilas en la Reserva Ecológica El Uno, dentro del Área Natural Protegida Reserva de la Biósfera Janos. Se identificaron un total de 18 tipos de presa, pero la especie mostró selectividad por dos géneros/especies, ya que cerca del 70% de la biomasa consumida fueron especies del género Sigmodon, mientras que el 21% de las muestras contenían Perognathus flavus. Además, dos especies de roedores identificadas constituyen nuevos registros de presa para la especie.

Primer development for amplification of toll-like genes for the assessment of adaptive genetic diversity in vulnerable grassland bird species

Assessing genetic diversity in species of conservation concern is a critical parameter to implement management plans that may increase their viability. Traditionally, genetic diversity has been assessed using neutral genes; nevertheless, recent perspectives have proposed that genetic variation under natural selection (adaptive genes) is more representative of the adaptive potential of a population or species. Toll-like receptors (TLR) are an innate immune gene family that binds to Pathogen Associated Molecular Patterns. These receptors evolved under positive selection and by coevolution; therefore, they represent adaptive genetic diversity. We designed and tested six pairs of primers that amplify TLR genes in seven grassland species, one of the most vulnerable North American bird groups. Analysis of the sequences showed that all were polymorphic and evolved under positive selection, with the exception of TLR3, which evolved neutrally. These primers may constitute a useful tool for conservation studies for grassland sparrow species.

New Records for Coahuila from a Riparian Bird Community in Northern Mexico

Abstract During an 18-month sampling effort along the Río Sabinas in Coahuila, Mexico (December 2004–August 2006), we observed eight confirmed and three potentially new breeding records, nine new non-breeding records, and eight rare records of birds for Coahuila. We also identified the Río Sabinas as a potential new breeding site in the state for five species. These data illustrate the considerable conservation value of this understudied area in northern Mexico.