It seems that putting the test near the nest was done deliberately: Cognition is challenging to assess in wild animals because testing paradigms often require individuals living under similar conditions to be tested repeatedly. Administering cognitive tests where wild animals rear their offspring can overcome this challenge because breeders often return reliably to a known location. [1]

[1] https://royalsocietypublishing.org/doi/10.1098/rsos.211343#d...