Musicians of the Night: The Nocturnal Singing of Willie Wagtails

The nocturnal singing of willie wagtails has fascinated researchers. Just as its ecological equivalent, the nightingale, it is famous for also singing at night in Asia, North Africa, and Europe. Their singing indicates the beginning of spring and the nightingale's mating season. In Australia, the less popular and nocturnal willie wagtail also howls by the moonlight.

The singing of birds is primarily considered a behavior during the daytime. At least 30 percent of birds, however, sing and call during the night and remain active in the day. The willie wagtail is among those birds. 

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The Willie Wagtail

Willie wagtails' songs have a twinkling sound. They are common around livestock because they feed on insects that accompany herds. 

A new study on these birds involved recording the songs of wagtails found in Victoria for three years. Their findings are reported in Behavioral Ecology and Sociobiology. The study confirms that these birds sing most in nights with a full moon.

The Methodology of the Study

The study recorded the willie wagtails' nighttime singing in eight full lunar cycles over four locations in Victoria. The researchers found that the wagtails sang longer as the moon became brighter.

Also, the authors found that the wagtails are similar to nightingales in that males invest in the singing. They start their yearly cycle during late winter to early in the spring.

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Bird Songs and Behavior

The study findings point to the possibility that the male wagtails sing during the night to have a better chance of mating a female and having offspring in spring. The results have not conclusively determined this, but by analyzing the function of diurnal singing, some clues can be seen.

Daytime singing is a signal for attracting mates. It also functions as a defense of the birds' territories from other intruders. The study authors believe that the likelihood of singing at night also serves to attract mates.

The reason for singing at night is unclear. Still, the researchers suggest that the males are probably catching up with the limited time in the mating season so that they take advantage of all the possible hours that they can sing so that their chances of success can be increased.

The study confirmed that willie wagtails sing by moonlight, which it has likely been doing for hundreds of its generations. The researchers also speculate that the birds may only be losing control with the brightness of the moon.

Defending Their Territory

Male wagtails also sing at night, regardless if they are with a partner or alone. The researchers think that this may be a form of territory defense and protection. Willie wagtails are fierce when it comes to defending their territory. They emit a rattle-like scolding sound that warns possible intruders who are too close to the wagtails' nests. They may also be doing this for the same reason at night.

Implications

The scientists then ask, does their behavior get affected when they live in or near cities, with lots of artificial lights shining throughout the night, which are brighter than the moon?

Anecdotal reports say the wagtails sing more due to these lights. Preliminary investigation shows that these lights may disrupt singing behavior at night, and further research may determine if this disrupted nocturnal singing of the willie wagtails also affects mating success.

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