Buitenkant doos: Crafty predators cryptic prey, Colour Silent w/titles Print, Tinbergen
A Tuscan product made in England
Titels in film: From the department of Zoology, University of Oxford - the ubiquitous Carrion Crow - His name is not undeserved - but apart from scavenging he eats insects ..... - hunts sandhoppers - and catches mammals - His keen vision makes him a menace even to well camouflaged prey - an Oystercatcher nest - A Plover chick - crows also explore continuously - While exploring, the learn about likely food - Field experiments analyse this learning - 1. Wild crows are taught a new camaflaged prey: meat under a cryptically coloured mussel shell - the first "lesson" is prepared - the area is observed from a hide - wild crows arrive - the next step - They have got the idea - Once successful, the crows continue ther search - This increases their efficiency range far beyond the "Direct Detection Distance" - Two examples of "direct detection" followed by searching - If unsuccessful the crows leave - It therefore pays even well camouflaged prey to live widely spaced - 2. How specific is this "Searching Image"? Crows used to red shells are offered other types (a) the training shell (pointed out) and alternative colours; (b) alternatives differing in shape and in texture - The choice situation - Summary of all choice tests: colour - Shape and texture - 3. Tests with hand-reared crows show how quickly they switch their attention - Off to work - A sample shell is shown - Some choices from sample - Thus merely by being found first a prey can endanger its likes living nearby - 4. But crows can hunt for more than one type of camouflaged prey - A red shell resembling red pebbles - An ochre shell - A black shell - The three types in situ, all with meat - Samples of one trimorphic and three monomorphic shell populations - the crows take to the new task - "Survivors" of four trimorphic and three monomorphic populations - Thus "hunting by Searching Image" may force prey animals (1) To live well spaced-out Example: larva of Biston betularia - (2) To develop polymorphism Example: Cepaea nemoralis
Beschrijving
Film in groen plastic doos, blaadje met aantekeningen/brief (in voorwerparchief). Film over het gedrag van kraaien.
Formaat
doos Diameter: 27 cm doos Hoogte: 2.6 cm spoel Diameter: 26.6 cm spoel Hoogte: 2 cm film Filmformaat: 16 mm film Speelduur: 16.32 min
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