With these cold winter nights upon us, the monkeys are often seen sunbasking in the early mornings. Once the sun hits the top of the trees, every available space in the sun is taken up by a monkey in this position (see photo). It is thought that such behaviour helps them thermoregulate as the sunlight warms their chest and belly; after a cold night of being huddled together for warmth. Depending on how cold it has been they can spend up to an hour just basking in the sun and grooming one another before starting another day of travelling and foraging.

Cheers 
Rich