No one likes a show-off, not least the male tui bird from New Zealand. It has recently been found that the males cannot cope with others who outdo them in the singing department, and so act more aggressively by getting all up in their face and upping their musical game.
Most of the time male birds sing for one of two reasons, either to attract a mate or to keep other fellas off their patch. Living in forests that contain trees that flower and fruit throughout the year, tuis (Prosthemadera novaeseelandiae) are usually pretty busy defending their territory from other males, and use their singing to let other birds in the region know who’s the boss.
But, as is often the case in nature, the songs are also thought to play a role in appealing to the opposite sex.
The tui birds can produce some astonishingly complex vocals, involving whoops, clicks, and hoots, and it is assumed that as with other songbirds, the females find those who perform the most impressive vocal acrobatics the most attractive. This is because the ability to produce such a wide and complex series of noises is likely a sign of overall health and fitness, meaning it helps the females pick the best father for her offspring.
But for those males that have successfully found and defended a productive patch of forest in the hope that it will bring all the females to him, males that can produce a complex song are something of a problem. This made researchers from New Zealand curious to see how breeding male tuis would react to other males singing more impressive songs on the edge of their territories, as in theory, it would increase competition.
The team tested territorial males by playing recordings of either simple or complex songs, and they found that the difference in responses was stark, publishing their results in Ibis International Journal of Avian Science. The most complex vocals, which contained more syllables in both number and type, as well as going on for a longer period of time, caused the defending males to act more aggressively, approaching within 30 centimeters (11.8 inches) of the speakers quickly, as well as spurring them on to perform more skillful warbling themselves.
This finding may be the first to show a direct link between male birds getting angry and physically aggressive to rivals who are out-performing them. It seems that rather than getting furious, the birds might just need to up their game.
[H/T: New Scientist]