Kea unfazed by unequal rewards when working together

Embargoed until: Publicly released:

Unlike humans who can become upset if they don’t receive an equal share, kea don’t seem to care if they work cooperatively and either they or their partner get a less desirable treat, according to new research from the University of Auckland. The researchers trained captive-bred kea at Christchurch's Willowbank Wildlife Reserve to exchange tokens for a reward; working in pairs, sometimes the kea received the same reward and sometimes they were given different values of reward. While kea are highly social and play a lot together in the wild, they don’t usually help each other out, so it’s unsurprising that they are unfazed by unequal rewards.

Journal/conference: Royal Society Open Science

Organisation/s: University of Auckland

Funder: This work was supported by a University of Auckland Doctoral Scholarship (M.H.) and a Rutherford Discovery Fellowship (A.H.T.).

Media Release

From: The Royal Society

Keas’ lack of response to inequity supports the hypothesized link to cooperation

It has been suggested that inequity aversion is a mechanism that evolved in humans to maximize the pay-offs from engaging in cooperative tasks and to foster long-term cooperative relationships between unrelated individuals. In support of this, evidence of inequity aversion in nonhuman animals has typically been found in species that, like humans, live in complex social groups and demonstrate cooperative behaviours. We examined inequity aversion in the kea (Nestor notabilis), which lives in social groups but does not appear to demonstrate wild cooperative behaviours, using a classic token exchange paradigm. We compared the number of successful exchanges and the number of abandoned trials in each condition and found no evidence of an aversion to inequitable outcomes when there was a difference between reward quality or working effort required between actor and partner. We also found no evidence of inequity aversion when the subject received no reward while their partner received a low value reward.


  • The Royal Society
    Web page
    The URL will go live after the embargo ends

News for:

New Zealand

Media contact details for this story are only visible to registered journalists.