De marzo de 1996 a febrero de 1997 se estudió la dieta del tecolote (Bubo virginianus) y de la lechuza (Tyto alba) y se monitoreó la comunidad de roedores en la Reserva de la Biosfera de Mapimí, Durango, México. El objetivo fue determinar la relación depredador-presa mediante la comparación del consumo y disponibilidad de roedores. Se analizaron 146 egagrópilas de 5 tecolotes y 63 de 4 lechuzas durante siete muestreos. El tecolote consumió once especies de roedores y la lechuza seis. Ambas especies consumieron aves, artrópodos y musarañas, pero el tecolote consumió además reptiles y helechos. De acuerdo a la densidad de roedores, el tecolote prefirió 8 especies (Perognathus flavus, Neotoma albigula,Reithrodontomys megalotis, Dipodomys merriami, Chaetodipus penicillatus, D. nelsoni, Ch. nelsoni y Peromyscus eremicus), mientras que la lechuza seleccionó cinco (P. flavus, Ch. penicillatus, D. nelsoni, D. merriami y P. eremicus). La dieta de ambas aves presentó escasa sobreposición, excepto durante su reproducción o crianza. El consumo de presas dependió del hábitat de forrajeo: el tecolote en matorrales arbustivos y pastizales y la lechuza sólo en pastizales. La selectividad de las presas dependió de sus altas densidades, mayor biomasa (N. albigula, D. merriami y D. nelsoni) y posiblemente de su fácil captura (P. flavus). El tecolote fue generalista y oportunista en su dieta, mientras que la lechuza fue generalista concierta selectividad hacia sus presas.
Exposure to pesticides during infancy is associated with numerous adverse health outcomes. The assessment of knowledge and perception of pesticides exposure and risk among children has not been thoroughly studied. The aim of the study was to evaluate the reliability and validity of a questionnaire that measures the knowledge and perception of exposure to organophosphate pesticides among rural schoolchildren. The questionnaire was administered to 151 schoolchildren between 9 and 13years from four Chilean rural schools. An internal consistency analysis of the ordinal alpha coefficient and a polychoric factor analysis for categorical data were used. The results show that the ordinal alpha was 0.95. Polychoric matrices of rotated components show the 17 questions summarized pesticide knowledge in five factors extracted after promax rotation. This factorial model explains 56.3% of the variance. The questions were grouped as follows: knowledge about pesticides (Factor 1); knowledge of health effects related to pesticides exposure (Factor 2); pesticide exposure through the growing of fruits and vegetables (Factor 3); perception and action against pesticides exposure at school (Factor 4); and perception and action against pesticides exposure at home (Factor 5). The questionnaire provides a useful tool for examining pesticide exposure in agricultural regions, allowing younger community members to participate.
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