4 results found containing all search terms.
... Science Frontiers ONLINE No. 49: Jan-Feb 1987 Issue Contents Other pages Home Page Science Frontiers Online All Issues This Issue Sourcebook Project Sourcebook Subjects Monarch Migration An Illusion "The epic autumn migration of the eastern monarch butterfly to wintering grounds in Mexico, where millions cluster on trees in semi-dormancy to await spring, has become known as one of the standard 'wonders of nature' in the decade since the Mexican winter clusters were found." There are, however, some flies in this ointment: Monarchs tagged in the north have never been found in the Mexican clusters. Fall-fattened monarchs can store only enough energy for a flight of about 200 miles -- far too short, unless they refuel along the way (no one knows if they do or not) ... and The monarchs seen in Mexico are almost always in pristine condition and show no wing wear or tattering. A.M . Wenner, University of California at Santa Barbara, thinks that the "appearance" of mass migration reported frequently from many locales may just be due to a curious fall habit of the monarchs. It seems that widely scattered individuals begin to fly into the wind, and the wind concentrates and channels them to local roosts where they spend the winter. In other words, there is no long distance migration at all. (Rensberger, Boyce; Washington Post, September 15, 1986. Cr. J. Judge) From Science Frontiers #49, JAN-FEB 1987 . 1987-2000 William R. Corliss ...
Terms matched: 2 - Score: 227 - 15 May 2017 - URL: /sf049/sf049p13.htm
... Science Frontiers ONLINE No. 116: Mar-Apr 1998 Issue Contents Other pages Home Page Science Frontiers Online All Issues This Issue Sourcebook Project Sourcebook Subjects Monarch Compasses Field experiments down the years suggest that migrating birds use a variety of strategies to chart their courses with high precision. The geomagnetic field, the sun, the stars, prominent landmarks, and even odors help guide them across the continents and open seas. But birds are considered highly evolved animals so their sophisticated navigational techniques are not especially surprising. Monarch butterflies, however, are mere insects, with tiny brains (navigation-data processors) and not much in the way of the environment sensors and internal clocks required for long-distance migration. Yet, some of these colorful insects manage to flutter up to 4,000 kilometers ... the eastern U.S . and Canada to their wintering grounds in Mexico. How do they do this? S.M . Perez et al have now shown that monarch butterflies are equipped with a sun compass; that is, they chart their courses by noting the sun's changing azimuth. This feat requires not only the measurement of solar azimuth but also reference to an internal clock. Humans cannot do this without artificial instruments. Furthermore, even on cloudy days, migrating monarchs fly in the proper direction (generally south-southwest). Apparently, they also have evolved a backup navigation system, perhaps a geomagnetic compass. (Perez, Sandra M., et al' "A Sun Compass in Monarch Butterflies," Nature, 387:29, 1997.) Comment. ...
Terms matched: 2 - Score: 221 - 15 May 2017 - URL: /sf116/sf116p10.htm
... Science Frontiers ONLINE No. 50: Mar-Apr 1987 Issue Contents Other pages Home Page Science Frontiers Online All Issues This Issue Sourcebook Project Sourcebook Subjects Monarchs slighted -- sorry!Contrary to the report in SF#49, at least one tagged monarch butterfly has been found among the wintering colonies in Mexico. In early 1976, a tagged individual from Chaska, Minnesota, was indeed found among a huge cluster in Mexico. Also, a few butterflies tagged in the northern states have turned up in Texas, well on their way to Mexico. (Urquhart, Fred A.; "Found at Last: The Monarch's Winter Home," National Geographic Magazine, August 1976. Cr. B. Ickes) Comment. So, it seems that A.M . Wenner ... the University of California researcher, will have to correct his records and perhaps modify his theory. From Science Frontiers #50, MAR-APR 1987 . 1987-2000 William R. Corliss ...
Terms matched: 2 - Score: 207 - 15 May 2017 - URL: /sf050/sf050p12.htm
... each pair is virtually a duplicate of its partner in shape, design, and colors. Yet, each member of each pair is a different species. Although the pairs are from the same geographical regions, it is not obvious why this astounding mimicry should occur. Here, one cannot invoke the explanation that one species gains an evolutionary advantage by mimicking an unpalatable species, as with mimics of the Monarch Butterfly. That is, there seems to be no evolutionary advantage to looking alike. (Miller, Julie Ann; BioScience, inside front cover, March 1994. Miller's editorial remarks are based upon a later article by H.F . Nijhout, who also supplied the photographs. Nijhout's article explains how butterfly wing patterns may have evolved.) Comment. Cases of remarkable ... Science Frontiers ONLINE No. 95: Sep-Oct 1994 Issue Contents Other pages Home Page Science Frontiers Online All Issues This Issue Sourcebook Project Sourcebook Subjects The urge to replicate: part i The inside front cover of the March 1944 issue of BioScience displays five pairs of colorful butterflies. Each member of each pair is virtually a duplicate of its partner in shape, design, and colors. Yet, each member of each pair is a different species. Although the pairs are from the same geographical regions, it is not obvious why this astounding mimicry should occur. Here, one cannot invoke the explanation that one species gains an evolutionary advantage by mimicking an unpalatable species, as with mimics of the Monarch Butterfly. That is, there seems to be no evolutionary advantage to looking alike. ( ...
Terms matched: 2 - Score: 155 - 15 May 2017 - URL: /sf095/sf095b10.htm
