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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 .
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 500 line segments defined above together form a shape in the Cartesian plane that resembles a bird with open wings. Looking at the line segments on the wings of the bird causes an optical illusion and may trick the viewer into thinking that the segments are curved lines. Therefore, the shape can also be considered as an optical artwork.
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 ...
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.
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 ...
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 ).
The four pigments in a bird's cone cells (in this example, estrildid finches) extend the range of color vision into the ultraviolet. [1]Tetrachromacy (from Greek tetra, meaning "four" and chroma, meaning "color") is the condition of possessing four independent channels for conveying color information, or possessing four types of cone cell in the eye.