Bird Calendars
NOTES FROM NATURE
By Jerry Toll
Questions and Answers
In the January "Bird's Eye View," I asked, "Which bird has the largest eye of any living creature? Why is it a bird and not, let's say, a mammal?"
Answer: Although the ostrich has the largest eye of any living bird, it may not be the largest of any living creature's.
My resource did not make that claim.It did say that any eye
has an upper limit to its size because at that point it becomes less efficient
at gathering light, and the image produced on the retina diminishes in quality.
The ostrich eye is at that limit but may not be the only living creature's at
that limit. This also explains why an elephant or whale has such small eyes in
relation to body size.
Question 2: "Which bird has the smallest eye in relation to body size of any bird?" Answer: Kiwis, which spend their lives foraging in low-light conditions under forest canopy and apparently depend less on an efficient eye when compared to other birds.
As a follow-up to my February "Nature Notes" on screech owls, these are the results of the Owl Census I conducted at DeSoto NWR February 6. I normally complete 35 stops but was unable to do the last five because of snow drifts on West Dike Trail. Still, the results were good compared to past years.
Twenty-two screech owls, 8 Barred Owls, and 3 Great-horned Owls answered the owl playback tape. East Dike Trail continues to be the most reliable place to find owls, probably due to screech owls' habit of using Wood Duck houses for roosting and nesting. East Dike Road parallels the lake where personnel have placed many houses close to the trail.
In 1999 the numbers were 29 screech owls, 8 Barred Owls, and 3 Great-horned Owls. In 2000, the best count was 12 screech owls, 5 Barred Owls and 4 Great-horned Owls.
Previous Notes from Nature:
07/17/11