lophorina superba

pango-doots  asked:

Hello! I am a high school student interested in a future with animals, avians in particular. One question I've always had on my mind is why certain species of birds aren't sexually dimorphic (parrots particularly) while many others are?

This is because of something called intersexual selection (also known as female choice) and is a type of sexual selection! When one sex (usually females) select mates based on specific characteristics. 

I great example of this is the indian peacock ( Pavo cristatus)

 Males are colourful and have giant ornate tail feathers, all in order to attract a female to mate with. The males with the longest, biggest and most colourful tails are found to be more successful when mating. 


Because these ornaments and bright colours are costly to the individual survival of the male. Firstly, they require alot of energy to grow, therefore only healthy males can grow these impressive tails. It therefore signals to the female that the male is fit and healthy, and therefore a good choice to mate with. 

Secondly, these bright colours, long heavy tails make the male peacock much more at risk of being preyed on by predators. Therefore it limits how long, bright and big these tails can be. It’s all about finding that balance.  

Hence why males in certain species that display sexual dimorphism, often are bright, colourful, or have over the top ornaments whilst females are often dull looking. 

Another popular example of this that you’ll proabably recognise is this superb bird of paradise (Lophorina superba). In which the male uses a combination of dance, and ornate feathers + colour to attrach the female. 

Some species of birds, that don’t show sexual dimorphism however still display intersexual selection. 

But not through visual decorations or colours like the above, but through other characteristics. Sparrows for example use song rather then colour or tail feathers. Males with more complex or elaborate songs are preferred by females than to other males.

Hope that answers your question.