ESTRUCTURA DE LA COMUNIDAD DE AVIFAUNA ASOCIADA AL MANGLAR EL CONCHALITO, BCS, MÉXICO BAJO DIFERENTES CONDICIONES DE MAREA

RESUMEN. El estudio de la estructura de comunidades de aves está relacionado con su relevante papel en el ecosistema, y cobra mayor importancia cuando se hallan expuestas al daño colateral por actividades antropogénicas. Esta investigación tuvo por objetivo determinar la variación de la estructura en la comunidad de aves en el manglar de El Conchalito, BCS, mediante la aplicación de índices ecológicos como diversidad (H´), dominancia (D) e índice de valor biológico (IVB), durante abril-julio de 2016 en la temporada de transición primavera - verano. Para describir el marco ambiental, se realizaron mediciones de temperatura, nivel de ruido y clorofila a. Igualmente, se utilizaron datos climatológicos. Se registraron 15 especies de aves acuáticas, marinas y/o costeras (5 órdenes, 7 familias y 9 géneros) y 3 especies de aves terrestres (2 órdenes, 2 familias, 3 géneros). Las máximas abundancias de aves se registraron durante los primeros muestreos. La diversidad osciló entre H´= 1.1 y H´= 1.8, con máximos al inicio y final del periodo de estudio. Esto se relaciona con mareas bajas e incremento en la riqueza de especies, respectivamente. El nivel de ruido y concentración de clorofila a no se asociaron directamente con los cambios observados en la estructura de la comunidad. La riqueza específica se asoció de manera directa con el incremento de temperatura. Las especies de aves más importantes fueron: Egretta thula (96.9%), Zenaida asiatica (88.7%), Numenius phaeopus (86.8%) y Egretta rufescens (83.8); de menor importancia fue Ceryle alcyon (28.2). Se identificaron 3 especies sujetas a protección (NOM-059-SEMARNAT-2010). Avifaunal community structure associated to El Conchalito mangrove, BCS, Mexico under different tide conditionsABSTRACT. The importance in the study of avian community structure relates to their relevant role in the ecosystem. Specially, when they are exposed to collateral damage by anthropogenic activities. The goal of this research was to determine the variation of avian community structure in the mangrove forest El Conchalito, BCS through the use of ecological indices such as diversity (H’), dominance (D), and the biological value index (IVB) in April-June of 2016 during the seasonal transition from Spring-Summer. To describe the environmental frame, measurements of temperature, noise level, and chlorophyll a were made, and other climatological data were used. A total of 15 species of aquatic, marine or shore birds were recorded (5 orders, 7 families and 9 genera), and 3 species of terrestrial birds (2 orders, 2 families and 3 genera). Maximum bird abundances were observed during the first sampling. Diversity values varied between H´= 1.1 and H´= 1.8, with maxima at the beginning and at the end of the study period. This was related with the low tides and the increase of species richness, respectively. Noise level and chlorophyll a concentration, were not associated directly with the changes observed in the community structure. Species richness was associated directly with temperature increase. The most important bird species were: Egretta thula (96.9%), Zenaida asiatica (88.7%), Numenius phaeopus (86.8%), and Egretta rufescens (83.8); less important was Ceryle alcyon (28.2). Three species protected under NOM-059-SEMARNAT-2010

Relating stream physical habitat condition and concordance of biotic productivity across multiple taxa

To explore the potential of assessments of stream geomorphic condition and habitat quality in evaluating lotic productivity, we investigated concordance of stream biotic productivity (aquatic macroinvertebrates, crayfish, fish, and belted kingfishers ( Ceryle alcyon )) and their physical habitat correlates in 18 streams in the Champlain Valley, Vermont, USA. Pearson correlation analysis indicated significant concordance between macroinvertebrate density and fish biomass (r = 0.76), between the density of macroinvertebrates in the orders Ephemeroptera, Plecoptera, and Trichoptera and fish biomass (r = 0.81), and between fish biomass and kingfisher brood weight (r = 0.54). We used principal component analysis followed by linear regression to investigate relationships between physical habitat condition and biotic productivity and to identify key components of physical habitat condition assessments. Our analysis supported the combined use of geomorphic and habitat assessments as a comprehensive indicator of stream physical habitat condition. We found relationships between habitat assessment scores and productivity measures of all taxa except crayfish, suggesting similar responses to physical condition across trophic levels. Our results encourage the use of additional taxa, in addition to widely used macroinvertebrate metrics, as indicators of the composite effects of physical habitat impairment in stream ecosystems.

Territorial Behavior in Belted Kingfishers, Ceryle alcyon, During Fall Migration

The Belted Kingfisher (Ceryle alcyon) exhibits territorial behavior during breeding and on the wintering grounds. However, behavior during migration is poorly documented. Here, I report on kingfishers exhibiting territorial behavior during fall migration along the shoreline of northern Lake Huron, Michigan.

Effects of substrate on prey use by belted kingfishers (Ceryle alcyon): a test of the prey abundance – availability assumption

Foraging trials were conducted using belted kingfishers (Ceryle alcyon) to examine relationships among prey abundance, availability, and use. Because these relationships are affected by the preference of the predator, I also determined the prey preference of belted kingfishers. Fish (Pimephales promelas and Catostomus commersoni) and crayfish (Orconectes spp.) were exposed to predation by 12 wild belted kingfishers under 4 treatments in which prey availability was manipulated by altering habitat structure. The preferred prey of belted kingfishers were relatively large fish (11–13 cm long). In structurally simple habitats, prey use by belted kingfishers reflected this preference. Complex habitat structure reduced the availability of preferred prey items and resulted in prey use that did not differ from the initial prey abundance distribution. These experiments demonstrated that prey abundance was not equivalent to availability and that habitat structure and prey preference had important effects on the relationships among prey abundance, availability, and use. Thus, evaluating the importance of prey resources to predators on the basis of prey abundance–use comparisons, while ignoring prey availability and the dynamic factors that influence it, may lead to erroneous conclusions.