7 results found.
... for example, the observation that the last egg laid by several species is distinctly lighter in color than the others in the clutch. This late-egg phenomenon is seen in the sparrows especially (House, Tree, Dead Sea, Grey-Head, and others). Common Terns, Fieldfares, Herring Gulls, and Moorhens also lay pale last eggs. Since the changes in the egg production line exact a cost in the females, there might be an adaptive explanation for the phenomenon; that is, the final paler egg may lead to increased survival of the participating species. To illustrate, in 1980, Yom-Tov suggested that: .. .this last odd egg might have evolved as a signal to potential brood parasites that the female has finished laying the clutch and has begun incubation. If a parasite lays its egg after incubation has commenced, then it would be unlikely to hatch, hence the potential parasite would benefit from heeding such a warning signal, if it could then find an alternative host nest where incubation had yet to commence. The signaling host would also benefit from avoiding the costs of warming an extra egg [the parasite's ] for some of the incubation period, costs that can be considerable, as well as the possible cost of having to rear an extra chick. G.D . Ruxton et al have used game theory to show that Yom-Tov's speculation has considerable merit. However, there are nonadaptive explanations. The females in the species that lay pale last eggs may simply run out of egg pigment, or they may ...
Terms matched: 1 - Score: 44 - 15 May 2017 - URL: /sf137/sf137p05.htm
... 2 to about 15 feet. All of the material making up the mounds seems to come from the immediate surroundings: coral debris, earth, and grains of iron oxide. The larger tumuli enclose a block of tuff, about 5 feet high and 6 feet in diameter, comprised of tumuli material held together by a calcareous cement or mortar. Some who have investigated these mounds believe that the presence of cement, presumably man-made, is proof-positive that the tumuli are the product of human activity. Other archeologists doubt this because the early settlers of New Caledonia did not use cement. Besides, there seem to be no other signs of human involvement. This has led to the hypothesis that the mounds were built by huge, now-extinct, flightless birds for the purpose of incubating their eggs. Some birds do indeed incubate their eggs in mounds today; and some 5,000 years ago New Caledonia did boast a giant bird (Sylviornia neocale doniae), which was 5-6 feet tall. The authors of the present paper feel that the giant bird hypothesis is just as reasonable as the theory that these mounds were built by ancient humans who knew how to make cement. (Mourer-Chauvire, Cecile, and Poplin, Francois; "Le Mystere des Tumulus de Nouvelle-Caledonie," La Recherche, 16: 76, September 1985. Cr. C. Mauge.) Comment. We find in our Handbook Ancient Man an article by A. Rothovius entitled: "The Mysterious Cement Cylinders of New Caledonia." The 1967 article covers much the ...
Terms matched: 1 - Score: 24 - 15 May 2017 - URL: /sf043/sf043p01.htm
... Atmospheric Pressure-Change Detection BBT2 Utility of Ultraviolet Vision in Birds BBT3 Echolocation: Parallel Evolution in Birds BBT4 Navigational Feats during Migration BBT5 Homing: Release Experiments BBT6 Curious Migration Phenomena: Navigation Errors? BBT7 Complexity and Sophistication of Avian Navigation BBT8 Inheritance of Migration Data BBT9 The Existence of Avian Migration BBT10 Sensitivity to Impending Weather and Earthquakes BBT11 Possible Unrecognized Senses BBT12 Remarkable Feats of Flight BBT13 The Origin of Avian Flight BBT14 Unanswered Questions Concerning Flightlessness BBT15 Some Curiosities of Avian Flight BBT16 Deep-Diving Capabilities BBT17 Vocal Mimicry in Birds BBT18 Birds That Vocally Mimic Only in Captivity BBT19 Vocal Mimicry of Hosts by Parasitic Species BBT20 Duetting BBT21 Chorusing BBT22 Large Vocal-Repertoire Sizes and High Speeds of Delivery BBT23 Female Singers BBT24 Whisper Songs and Subsongs BBT25 The Two-Voice Phenomenon BBT26 Some Curiosities of Avian Vocalizations BBT27 Incubator Nests BBT28 Woven and Sewn Nests BBT29 Nests Containing Protective Materials BBT30 Bowers BBT31 Nest Curiosities BBT32 Tool Use BBT33 Communication between Chick Embryos BBX AVIAN INTERFACE PHENOMENA BBX1 Unusual Attacks on Humans BBX2 Unusual Predators of Birds BBX3 Unusual Bird-Animal Psychological Interfaces BBX4 Curious Associations of Birds with Other Animals and Plants BC BIOCHEMISTRY Titles not yet posted BF FISH Titles not yet posted BG GENETICS Titles not yet posted BH HUMANS BHA EXTERNAL APPEARANCE AND MORPHOLOGY BHA1 Human Asymmetry BHA2 The Appearance of Beauty in the Human Lineage BHA3 General Physique Correlated with the Month of Birth BHA4 Human Body Badly Designed for Swimming BHA5 The Apparent Physical Degeneration of Humans BHA6 Human Physical Degeneration and Genius BHA7 Variability of External Appearance BHA8 Discordances in the Appearances of Identical Twins BHA9 Mirror-Image Twins BHA10 The Apparent Primitive Character of Some Features of the ...
Terms matched: 1 - Score: 18 - 15 May 2017 - URL: /cat-biol.htm
... Science Frontiers ONLINE No. 84: Nov-Dec 1992 Issue Contents Other pages Home Page Science Frontiers Online All Issues This Issue Sourcebook Project Sourcebook Subjects It Came From Within Life did, that is! Forget that warm little pond where life incubated according to all the textbooks. Instead, says T. Gold, an iconoclastic Cornell physicist, life began in rocky fissures deep down in the earth's crust. The idea is not as unlikely as it sounds. Look at the most primitive life forms we know, the archaebacteria. They like heat, need neither air nor sunlight, and prosper on sulfur compounds for sustenance. Such bacteria are today found in boreholes as deep as 500 meters, in thermal springs, and around deepsea vents. Gold surmises that these archaebacteria migrated to the surface long ago, where they evolved into higher forms of life. "Gold argues, moreover, that the earth's interior would have provided a much more hospitable environment for proto-life four billion years ago than the surface would have, ravaged as it was by asteroids and cosmic radiation. And if life emerged within the earth, then why not within other planets? 'Deep, chemically supplied life,' Gold says, 'may be very common in the universe.'" (Horgan, John; "It Came from Within," Scientific American, 267:20, September 1992.) From Science Frontiers #84, NOV-DEC 1992 . 1992-2000 William R. Corliss ...
Terms matched: 1 - Score: 15 - 15 May 2017 - URL: /sf084/sf084b05.htm
... Science Frontiers ONLINE No. 119: Sep-Oct 1998 Issue Contents Other pages Home Page Science Frontiers Online All Issues This Issue Sourcebook Project Sourcebook Subjects Murder In The Nest In a recent issue of BioScience, R.B . Payne authored an excellent review of brood parasitism in birds. Brood parasites lay their eggs in the nests of other species, which then incubate the eggs and raise the alien chicks. The parent parasites are thus free to forage, hang out, and parasitize more nests. Brood parasitism is such a successful and easy way of life that 136 species of cuckoos, 5 species of cowbirds, 20 finches, and South America's Blackheaded Duck have adopted it. Brood parasitism fascinates ornithologists because it involves war between the parasites and their hosts. Since host species may eject parasite eggs or fail to nurture parasite chicks, brood parasites have evolved mimicry as a powerful weapon in these battles. Mimicked are host eggs, host nestlings, and host vocalizations. But the most insidious weapons of all involve the outright murder of host chicks. To this end, parasite chicks have evolved some special weapons and behaviors. Some cuckoo chicks evict host eggs or chicks by squirming under them and positioning them in a specially configured hollow on their backs. Then, pushing upward and outward to the rim of the nest, they dump their cargo over the edge. Other brood parasites are more direct and bloodthirsty. "Nestling African honeyguides have bill hooks to stab and kill their nestmates and the brood parasitic American striped cuckoos have independently evolved hooks and pincers to kill." (Payne ...
Terms matched: 1 - Score: 15 - 15 May 2017 - URL: /sf119/sf119p04.htm
... Science Frontiers ONLINE No. 70: Jul-Aug 1990 Issue Contents Other pages Home Page Science Frontiers Online All Issues This Issue Sourcebook Project Sourcebook Subjects Wandering Albatrosses Really Wander Tracks of three Wandering albatrosses in the southern Indian Ocean. Six male wandering albatrosses nesting on Crozet Island, between South Africa and Antarctica, were fitted with tiny (180-gram) transmitters and tracked by satellite. Their flights were amazing: "Tracks of wandering albatrosses in the southwestern Indian Ocean showed that they covered between 3,600 and 15,000 km in a single foraging trip during an incubation shift. They flew at speeds of up to 80 km per h and over distances of up to 900 km per day. They remained active at night, particularly on moonlit nights..." (Jouventin, Pierre, and Weimerskirch, Henri; "Satellite Tracking of Wandering Albatrosses,; Nature, 343:746, 1990.) From Science Frontiers #70, JUL-AUG 1990 . 1990-2000 William R. Corliss ...
Terms matched: 1 - Score: 13 - 15 May 2017 - URL: /sf070/sf070b07.htm
... Science Frontiers ONLINE No. 61: Jan-Feb 1989 Issue Contents Other pages Home Page Science Frontiers Online All Issues This Issue Sourcebook Project Sourcebook Subjects Egg Mimicry In Cuckoos In Britain, cuckoos mainly parasitize five species of smaller birds. They do this by laying their eggs in the hosts' nests. After hatching, the young cuckoos grow much faster than the young of the host species. Soon the cuckoo is able to eject the host's young from the nest and get all the food brought by the parents. Actually, the cuckoo is so aggressive in this business of parasitization that, when it finds a host nest with eggs so far along in incubation that parasitization is impractical, it destroys the whole nest. This usually forces the host birds to lay fresh eggs, giving the cuckoo a chance to parasitize the nest. The most remarkable thing about cuckoo parasitism is the birds' ability to match the eggs of the host species in size, spottedness, background color, and darkness. The eggs of all five species commonly parasitized in Britain are much smaller than a bird the size of the cuckoo would normally lay; but the cuckoo still manages to lay eggs of just the right size. When the bona fide eggs of the five parasitized species are placed side-by-side with the mimics layed by the cuckoos, the matches are uncanny - except in the case of the dunnock, which the cuckoo doesn't try to mimic at all. The question, of course, is how the cuckoos do it. American cuckoos rarely parasitize the nests of other ...
Terms matched: 1 - Score: 13 - 15 May 2017 - URL: /sf061/sf061b07.htm
