The 2011 Ig Nobel Physiology Prize was shared by Anna Wilkinson (of the UK), Natalie Sebanz (of the Netherlands, Hungary, and Austria), Isabella Mandl (of Austria) and Ludwig Huber (of Austria) for their study ‘No Evidence of Contagious Yawning in the Red-Footed Tortoise.’ (published in Current Zoology, vol. 57, no. 4, 2011. pp. 477-84.)
Since then, research investigating Contagious Yawning in other species has not abated – two recent studies have added to the growing list* of animals which have been shown to contagiously yawn.
See: Presence of contagious yawning in sheep (2016)
and When Yawning Occurs in Elephants (2017)
* The current list includes (but is prob. not limited to)
Humans
Chimpanzees
Bonobos
Orangutans
Macaque monkeys
Gelada baboons
Wolves
Domestic dogs
Rats
Budgerigars
Sheep
Elephants