Birdsong is a classic example of a learned social behaviour. Song behaviour is also influenced by genetic factors, and understanding the relative contributions of genetic and environmental influences remains a major goal. In this study, we take advantage of captive zebra finch populations to examine variation in a population-level song trait: song variability. Song variability is of particular interest in the context of individual recognition and in terms of the neuro-developmental mechanisms that generate song novelty. We find that the Australian zebra finch Taeniopygia guttata castanotis ( TGC ) maintains higher song diversity than the Timor zebra finch T. g. guttata ( TGG ) even after experimentally controlling for early life song exposure, suggesting a genetic basis to this trait. Although wild-derived TGC were intermediate in song variability between domesticated TGC populations and TGG , the difference between domesticated and wild TGC was not statistically significant. The observed variation in song behaviour among zebra finch populations represents a largely untapped opportunity for exploring the mechanisms of social behaviour.

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Birdsong is a classic example of a learned social behavior. Like many traits of interest, however, song production is also influenced by genetic factors and understanding the relative contributions of genetic and environmental influences remains a major research goal. In this study we take advantage of genetic variation among captive zebra finch populations to examine variation in a population-level song trait: song variability. We find that zebra finch populations differ in levels of song variability. Domesticated T. g. castanotis populations displayed higher song diversity than more recently wild-derived populations of both zebra finch subspecies T. g. castanotis and T. g. guttata, the Timor zebra finch. To determine whether these differences could have a genetic basis, we cross-fostered domesticated T. g. castanotis and Timor zebra finches to Bengalese finches Lonchura striata domestica. Following cross-fostering, domesticated T. g. castanotis maintained a higher level of song diversity than T. g. guttata. We suggest that the high song variability of domesticated zebra finches may be a consequence of reduced purifying selection acting on song traits. Intraspecific differences in the mechanisms underlying song variability therefore represent an untapped opportunity for probing the mechanisms of song learning and production.

Western salsify has recently formed dense stands in Conservation Reserve Program (CRP) lands in north-central Montana. Our objective was to test the effects of various herbicide treatments and mowing on western salsify and associated vegetation in CRP lands. Six herbicide treatments and one mowing treatment were applied at three sites in 2010. Herbicide treatments included combinations of glyphosate, 2,4-D, dicamba, and/or metsulfuron-methyl applied when western salsify was either in the rosette or early flowering stage. Mowing was applied at the early flowering stage. Herbicide treatments reduced western salsify and increased perennial grass at one of the three sites, which was the site most dominated by western salsify. When dicamba (0.14 kg ae ha−1) plus 2,4-D (0.48 kg ae ha−1) was applied at the rosette stage, western salsify adult plant density and biomass were reduced to zero and perennial grass biomass increased by 108% in 2010. In 2011, western salsify adult plant density was lower across all herbicide treatments compared to the mowed and nontreated plots. Annual grass density increased by up to 400% when herbicide applications including metsulfuron-methyl were applied at the early flowering stage. Mowing did not control western salsify. Results suggest dicamba plus 2,4-D applied at the rosette stage can provide effective control of western salsify and increase perennial grasses without stimulating the emergence of annual grasses.