Flying Birds Wallpaper

The table on the next page gives longevity records (years-months) of wild birds. Small differences among these figures should not be taken too seriously. For one thing, they represent the upper end of a range -- and the range of any measurement is a statistic that almost always increases with the number of measurements. If, for instance, you record the heights of a random sample of 10 American women, and then of another sample of a million American women, both the tallest and the shortest woman are virtually certain to be in the larger sample. So the minimum life-spans of bird species that are frequently banded are more likely to be greater than those of species rarely banded, everything else being equal. It seems likely, for example, that the short record for the Northern Shrike is simply a result of a low frequency of banding. At any rate, remember that with the exception of efforts that may later be corrected, the numbers on the list can only increase. Remember also that these figures are maximum recorded ages. While at one point the maximum record for the Purple Finch was 10 years (it has since been extended to almost 12), of 1,746 recoveries from 21,715 banded individuals, only I lived 10 years, 6 lived 8 years, and 18 lived 7 years. All the remainder lived less than 7 years. In short, the maximum life-span is far longer than the median life-span (the length of the life of the individual that lives longer than half the population and shorter than the other half), which in songbirds is usually only a year or two.