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Identifying a Purple Martin

Dimensions of the Bird:


According to The CornellLab, the ranges of measurements for the purple martin are as follows (Charles, 2021): [with the averages being in parentheses]:

  • Length from head to tail: 7.5–7.9 in / 19–20 cm (7.9 inch/20cm) 

  • Weight: 1.6–2.1 oz / 45–60 g (1.94oz / 55g)

  • Wingspan - the maximum extent across the wings: 15.3–16.1 in / 39–41 cm (15 inch / 38cm)

Purple martins have a forked tail, which is when the tail of a bird is cleft (split into two distinct parts). When spread out, these tails are roughly twice as long as their inner feathers giving them a high ratio of lift to drag (LID), which in other words, allows them to generate better turning momentum and more braking power. Hence, these tails increase their agility making the changes of directions during flight easy and quick (Thomas, 1995).


Special Traits/Behaviors

a) Forked Tail

b) Delayed Plumage Maturation

c) Sexual Dimorphism

d) Unique Songs

Purple martins also have a condition called delayed plumage maturation, which is a fancy way of saying that it takes them two years to acquire a full adult plumage. (Hawkins, 2011) With that said, male and female birds that haven’t matured possess different colour patterns and characteristics in their plumage. (Young birds are considered any under the age of a year old)

On top of that, purple martins are sexually dimorphic, described as 
‘’the systematic difference in form between individuals of different sex in the same species.’’ (Thesaurus, 1998)
In other words, we can tell the difference between sexes in this species by looking at other traits than their reproductive organs.

Purple martins sing with boisterous, throaty and raspy chirps. Their song tend to last around 4 seconds, and the onomatopoeia used to describe their singing is: pre pre, choo chert, zweet zwack.

Distinguishing Sexes and Ages of Purple Martins

Adult Male:


Adult males are the only purple martin with iridescent feathers covering the entire body, including the tail and feathers, only showing past the third calendar year of their life.

Adult Female:


Adult females have no purple feathers on their chest, belly or undertail; they are only seen on the bird's head. Also, their undertail coverts vary but are most commonly brown/taupe feathers with white trim on the outer edge.

Subadult Male:


Subadult males are often the hardest to identify. They may have minor amounts of purple feathers on their chins, throats, bellies, or undertails. 

Subadult Female:


Subadult females have a much lighter purple and brownish colour on their back with a white or light brown covered undertail. 



Hatching year purple martins cannot be determined by sight but only by their stubbier tails with a very hard-to-see undertone.

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