Recapture probability, flight morphology, and microorganisms

Abstract

Microorganisms on and within organisms are ubiquitous and interactions with their hosts range from mutualistic over commensal, to pathogenic. We hypothesized that microorganisms might affect the ability of barn swallows Hirundo rustica to escape from potential predators, with positive associations between the abundance of microorganisms and escape ability implying mutualistic effects, while negative associations would imply antagonistic effects. We quantified escape behavior as the ability to avoid capture in a mist net and hence as a small number of recaptures. Because recapture probability may also depend on timing of reproduction and reproductive success, we also tested whether the association between recapture and microorganisms was mediated by an association between recapture and life history. We found intermediate to strong positive relationships between recapture probability and abundance of Bacillus megaterium, but not abundance of other bacteria or fungi. The abundance of B. megaterium was associated with an advance in laying date and an increase in reproductive success. However, these effects were independent of the number of recaptures. This interpretation is supported by the fact that there was no direct correlation between laying date and reproductive success on one hand and the number of recaptures on the other. These findings have implications not only for predator–prey interactions, but also for capture-mark-recapture analyses of vital rates such as survival and dispersal.

Estimating mortality rates among passerines caught for ringing with mist nets using data from previously ringed birds

“…Spotswood et al (2012) reported that individuals which were captured more often had lower incidence of mortality and suggested they were likely to be fitter compared with transient individuals, the latter both not holding a territory and, by definition, having a lower probability of recapture. However, other studies show that birds appear to learn to avoid nets once caught, at least for a short while (Simons, Winney, Nakagawa, Burke, & Schroeder, 2015), and that individuals in poorer condition may be captured more frequently, as they are less able to avoid capture (Al Rubiaee, Al-Murayati, & Møller, 2017). We did not find any relationship between the number of previous captures and the risk of mortality, although all the birds in our study had to have been captured once before entering the dataset.…”

“…This may particularly be the case for individuals who were in poor condition when caught and at least some of these individuals for which no specific cause of death was apparent may have died for reasons unconnected with capture. There is some evidence, for example, that individuals with higher bacterial infection loads are less likely to evade capture (Al Rubiaee et al, 2017). However, a lack of population-level effects does not negate welfare concerns for individuals and, as we demonstrate here, efforts should be made to identify species or groups most at risk.…”

“…Trap performance criteria have been proposed for mammals (Powell & Proulx, 2003); however, there is a general scarcity of information and published rates may not be widely representative. Researchers need to openly assess and report the impacts of their study methods in ways that are amenable to meta-analysis (Arnqvist & Wooster, 1995). This study provides a way of using existing data to…”

Not so black, not so white: differences in microorganism load of contiguous feathers from white stork chicks

“…FMA is a highly selective medium for keratinophilic bacteria, for which keratin is the sole source of carbon and nitrogen. Hence, only bacteria that can digest keratin are able to proliferate, thus enabling quantification of the feather-degrading bacterial load ( Al Rubaiee et al 2017a , 2017b ).…”

“…The observed developing mycotic growths were recorded under a stereoscopic binocular microscope, and subsequently individually and directly transferred to a Sabouraud dextrose agar medium with chloramphenicol (50 mg/L). The resulting products were incubated further at 28 ± 2°C for 2 weeks to obtain a pure isolate for identification purposes ( Al Rubaiee et al 2017a , 2017b ).…”