  Ascertaining the number, type, and location of plant, insect, and animal
species is essential for biodiversity conservation. However, comprehensively
monitoring the situation only through public fixed-point surveys is
challenging, and therefore information voluntarily provided by citizens assists
in ascertaining the species distribution. To effectively encourage the
citizens' data sharing behavior, this study proposed a prosocial incentive
scheme in which, if they provide species information, donations are made to
activities for saving endangered species. We conducted a field experiment with
users (N=830) of a widely-used Japanese smartphone app to which they post
species photos and measured the incentive's effect on their posting behavior.
In addition, we measured the effect of a financial incentive scheme that
provides monetary rewards for posting species photos and compared the two
incentives' effects. The analyses revealed that while the prosocial incentive
did not increase the number of posts on average, it did change the contents of
posts, increasing the proportion of posts on rare species. On the contrary, the
financial incentive statistically significantly increased the number of posts,
in particular, on less rare and invasive species. Our findings suggest that the
prosocial and financial incentives could stimulate different motivations and
encourage different posting behaviors.
