It has been demonstrated that predators can select against high growth rates and risk-taking behaviour by eating out the bold, feeding-machine type of fish (Biro et al. 2004; 2006), and the case is the same if the predator happened to be human (Biro & Post 2008).
In a recent paper published in TREE, Biro & Dingemanse (2009) have compiled evidence for animal personality based sampling bias in ecological studies. The story is fairly simple: in many cases, especially when passive methods (like non-baited traps) are used, researchers will end up with far more bold individuals than they would find in a truly representative sample. There are examples listed from sunfish through squirrels to bighorn sheep. A Hungarian colleague of mine is working on similar issues with birds, and the results likely to be just similar.
I guess I don’t have to go into detailed speculations about how many of the published studies can be biased, and how many traits (obviously not only behavioural ones, but almost anything else) could be falsely estimated for the studied populations. Pretty worrying!
/I found no studies about the effect of the sampling researchers’ personality on the quality of samples yet./
Biro PA, Abrahams MV, Post JR, Parkinson EA (2004) Predators select against high growth rates and risk-taking behaviour in domestic trout populations. Proceedings of the Royal Society London B 271:2233-2237. doi:10.1098/rspb.2004.2861
Biro PA, Abrahams MV, Post JR, Parkinson EA (2006) Behavioural trade-offs between growth and mortality explain evolution of submaximal growth rates. Journal of Animal Ecology 75: 1165-1171. doi: 10.1111/j.1365-2656.2006.01137.x
Biro PA, Post JR (2008) Rapid depletion of genotypes with fast growth and bold personality traits from harvested fish populations. Proceedings of the National Academy of Sciences USA 105: 2919-2922. doi:10.1073/pnas.0708159105
Biro PA, Dingemanse NJ (2009) Sampling bias resulting from animal personality. Trends in Ecology and Evolution 24: 66-67. doi:10.1016/j.tree.2008.11.001