Birds such as the cowbird that lay their eggs in the nests of other birds have evolved strategies to disguise their chicks and not just their eggs. María De Mársico and her colleagues at the University of Buenos Aires observed eggs or hatchlings from the screaming cowbird (Molothrus rufoaxillaris; pictured left) or the shiny cowbird (Molothrus bonariensis) that were placed or laid in the nests of the baywing (Agelaioides badius; right), and measured the fledglings' survival rates. The researchers found

The primary purpose of the study was to determine if girls in one school receiving nurse counseling plus an after-school Physical Activity Club showed greater improvement in physical activity, cardiovascular fitness, and body composition than girls assigned to an attention control condition in another school (N = 69). Linear regressions controlling for baseline measures showed no statistically significant group differences, but directionality of differences was consistent with greater intervention group improvement for minutes of moderate to vigorous physical activity/hour (t = 0.95, p = .35), cardiovascular fitness (t = 1.26, p = .22), body mass index (BMI; t = −1.47, p = .15), BMI z-score (t = −1.19, p = .24), BMI percentile (t = −0.59, p = .56), percent body fat (t = −0.86, p = .39), and waist circumference (t = −0.19, p = .85). Findings support testing with a larger sample.

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