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Studies in bird behaviour include the use of tamed and trained birds in captivity. Studies on bird intelligence and song learning have been largely laboratory-based. Field researchers may make use of a wide range of techniques such as the use of dummy owls to elicit mobbing behaviour, and dummy males or the use of call playback to elicit ...
The eyes are small, but the pupils are relatively large, allowing the highest light-gathering capacity of any bird (f-number of 1.07). [8] The retina is dominated by rod cells , 1,000,000 rods per mm 2 , the highest density of any vertebrate eye, [ 8 ] which are organised in layers, an arrangement unique among birds but shared by deep-sea fish .
The zoologist J.L. Cloudsley-Thompson argued that a large bird would be able to produce more young than a small bird. [4] Williams replied that this would be a bad reproductive strategy, as large birds have lower mortality and therefore a higher residual reproductive value over their whole lives (so taking a large short-term risk is unjustified ...
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Blue jay eating at a feeder Bird feeder in a garden. A birdfeeder, bird table, or tray feeder is a device placed outdoors to supply bird food to birds (bird feeding).The success of a bird feeder in attracting birds depends upon its placement and the kinds of foods offered, [1] as different species have different preferences.
In chemistry and physics, the dimensionless mixing ratio is the abundance of one component of a mixture relative to that of all other components. The term can refer either to mole ratio (see concentration ) or mass ratio (see stoichiometry ).
Large sums of money are spent by ardent bird feeders, who indulge their wild birds with a variety of bird foods and bird feeders. Over 55 million Americans over the age of 16 feed wild birds and spend more than $3 billion a year on bird food, and $800 million a year on bird feeders, bird baths, bird houses and other bird feeding accessories. [22]
The regular feed conversion ratio, i.e. output fish mass divided by total feed mass. The conversion ratio only taking into account the fish-based component of fish feed, called the FIFO ratio (or Fish In – Fish Out ratio). FIFO is fish in (the mass of harvested fish used to feed farmed fish) divided by fish out (mass of the resulting farmed ...