Neil E. Coughlan

“Step by step”: high frequency short-distance epizoochorous dispersal of aquatic macrophytes

Aquatic macrophytes can successfully colonise and re-colonise areas separated by space and time. The mechanisms underlying such “mobility” are not well understood, but it has often been hypothesised that epizoochory (external dispersal) plays an important role. Yet, there is only limited, and mostly anecdotal, evidence concerning successful epizoochorous dispersal of aquatic macrophytes, particularly in the case of short-distance dispersal. Here we examine in situ and ex situ dispersal of aquatic macrophytes, including three invasive alien species. A high frequency of Lemna minor Linnaeus dispersal was observed in situ, and this was linked to bird-mediated epizoochory. We concluded that wind had no effect on dispersal. Similarly, in an ex situ examination Lemna minuta Kunth and Azolla filiculoides Lamarck, were found to be dispersed with a high frequency by mallard ducks (Anas platyrhynchos). No dispersal was measured for Elodea nuttalli (Planchon) H. St. John. It is concluded that short-distance or “stepping-stone” dispersal via bird-mediated epizoochory can occur with high frequencies, and therefore can play an important role in facilitating colonisation, range expansion and biological invasion of macrophytes.

Bat collisions with civil aircraft in the Republic of Ireland over a decade suggest negligible impact on aviation safety

Globally, collisions between wildlife and aircraft are a serious threat to aviation safety. While reported collisions have increased in recent years, the impact of these collisions on air safety is rarely quantified. Here, we report all bat collisions (bat strikes) with civil aircraft known to have occurred in the Republic of Ireland over the 10-year interval, 2006–2015. Morphological and/or DNA identification techniques were used to identify chiropteran specimens to species level. In total, carcasses or remains from five bat strikes—three Leisler’s Nyctalus leisleri, one Soprano Pipistrelle Pipistrellus pygmaeus, and one Natterer’s Myotis nattereri—were recovered. The collisions are discussed in the context of (a) the rate of chiropteran strikes in relation to the number of civil aircraft movements and (b) possible damage caused to aircraft. Overall, however, bat strikes with aircraft appear to have a negligible effect on civil aircraft safety.