These northbound movements begin at first light, and they continue through morning and even into the afternoon. Bob notes that although birds overshoot their destination on land as well as over the Gulf, they are easier to study from the oil platforms. Gulf Fritillaries have been most common. Pink-spotted Hawkmoths have been most abundant, followed by Tersa Sphinx and Mournful Sphinx, plus a few vagrant Esso Sphinx. Last week we asked why Dave Evans marks owl flight feathers with a permanent marker, and how long these markings last.
Permanent markers can last through rain and even sunlight as long as the feathers last.
He marks the wing feathers to help in aging the owl the next time it is caught. If the saw-whet owls molt their wing feathers in a certain order and the bird is caught again, they will be able to tell how old it is. The permanent marker lasts until the owl molts the feather. How You Can Help Track Spring's Journey North Copyright 1998 Journey North. All Rights Reserved.