owls into the 21st century is not well-understood. Siberian snowy owls are frequently victim to baited fox traps, with possibly up to around 300 killed in a year based upon very rough estimates. Warfarin poisoning in use as rodenticides are known to kill some wintering snowy owls, including up to six at Logan Airport alone. Mercury concentrations, most likely through bioaccumulation, have been detected in snowy owls in the Aleutian Islands but it is not known whether fatal mercury poisoning has occurred. PCBs may have killed some snowy owls in concentration. Some airports have advocated and instituted the practice of shooting owls to avoid birdstrikes but successful translocation is possible and preferred given the species protected status. Climate change is now widely perceived to perhaps the primary driver of the snowy owl's decline. As temperatures continue to rise, abiotic factors such as increased rain and reduced snow are likely to effect lemming populations and, in turn, snowy owls. These and potentially many other issues (possibly including modifying migrating behavior, vegetation composition, increased insect, disease and parasite activities, risk of hyperthermia) are a matter of concern. Additionally, reduction of sea ice, which snowy owls are now known to rely extensively on, as a result of warming climates, impacts could be significant. The effect of climate change was essentially confirmed in northern Greenland where a perhaps irrevocable collapse of the lemming population was observed. From 1998 to 2000, the lemming numbers appeared to have quickly declined. The number of lemmings per hectare (ha) is less than one-fifth of what it once was in Greenland (i.e. from 12 lemmings per ha to less than 2 per ha at peak). This is almost certainly correlated with a 98% decline in owl productivity as well as that of the local stoats (the long-tailed jaeger and Arctic foxes, though previously thought to be almost as reliant on lemmings, seem to be more loosely coupled and more generalized and did not decline as much). The amount of lemming mounds is much less than it once in northern Greenland and any variety of population cycle has been apparently abandoned by what remains of the lemmings. In popular culture The Harry Potter books by J. K. Rowling, and subsequent films of the same name, feature a female snowy owl named Hedwig. Concern was expressed by some in the media that the popularity of the Harry Potter films would cause