Q. With so many birds in the world, and in our urban environment, you would think we would see dead birds all over the place. But we don't. So, where do birds go to die?

A. First, wild animals attempt to hide their illnesses, otherwise they would be quickly signaled out by predators. A sick bird or mammal will attempt to hide or secret itself away, so oftentimes illness and death will occur in a place hidden from our view. But more importantly, a dead bird is quickly consumed by scavengers ranging from vertebrates to beetles to bacteria and fungi. Death is quickly recycled into life. Some large peri-urban birds are more easily spotted when they die. This is why we can use dead birds (crows, jays, and magpies) as an indicator of West Nile virus transmission.

Q. Last year I volunteered to be a part of the Cornell University's ivory-billed woodpecker volunteer research effort. Did the sweep of the West Nile virus across North America have an impact on the woodpecker populations?

A. As far as we know, the spread of WNV did not push any bird species to the point of extinction. Small, isolated populations are at greatest risk, and the loss of even a single ivory-billed woodpecker to WNV could be disastrous. Although WNV certainly killed many, many birds across North America, most species have the ability to buffer these losses by successful reproduction in future years. Woodpeckers as a group are much less prone to die from WNV than corvids such as crows and jays. Because of natural selection, susceptible birds within any given species will become less numerous, and the survivors of WNV will pass on their genes to future generations, decreasing the impact of WNV in future years.

Walter Boyce is a UC Davis professor of veterinary medicine and co-director of the UC Davis Wildlife Health Center.

Q. Those with ties to the agriculture industry are greatly concerned about declining bee populations. Indeed, all of us who eat should be concerned. Are we any closer to understanding the cause of, and the solution to the problem?

A. The number of managed honey bee colonies has been declining gradually from a high of over 5 million colonies, right after World War II, to our current reported number of about two and a half million. We have been at the current level for about five years. North American beekeepers expected average winter colony losses of 5 to 10 percent.

Beekeepers whose bees have been affected by colony collapse disorder lost anywhere from 30 percent to all of their colonies over the winter. Such large unexpected losses have been reported sporadically in U.S. bee industry publications since the late 1800's, more recently in 1963-65 and 1975. Our current problem began in the winter of 2004, was less severe in the winter of 2005, and increased in the winters of 2006 and '07.

The major U.S. research emphasis on this problem has examined potential pathogens (fungal, bacterial, and viral), potential chemical contamination (171 potential chemical residues were searched for in dead bees, live bees, brood, stored honey, stored pollen, and beeswax) and possible consequences of moving colonies so many times for purposes of pollinating commercial agricultural crops or producing honey. Surveys have been conducted to determine the times and places where such losses occurred and possible correlations between losses and locations, or between losses and various beekeeping practices. Up to this point, the studies have not incriminated any single specific cause that is common to the losses. However, it has been determined that there are a very large number of potentially damaging causes impacting the bees, and perhaps they simply are unable to deal with the sum total.

Eric Mussen is a UC Cooperative Extension apiculturist in the Department of Entomology at UC Davis and is on the faculty of the Henry H. Laidlaw Jr. Honey Bee Research Facility.

Due to the volume of Ask it! submissions, not all questions can be answered online.

Previous Ask it! questions:

Q: Weight loss is based on expending more energy than consumed, and for every 3,000 calorie deficit you lose one pound. Assuming both an obese person and someone slightly overweight eat proportionate calories and exercise at equal levels, why does the obese person lose a lot more weight in the same amount of time than the slightly overweight person?

Q. Iowa and New Hampshire aren't exactly representative of the nation as a whole and yet they have so much influence on the presidential nominating process. Why are these states first every time?

Q. Would taking steroids or human growth hormone for a brief time, to aid recovery from an injury, be worth it? As a 50-plus athlete I don't care about improved performance, I care about decreasing injury recovery time.