No evidence for memory interference across sessions in food hoarding marsh tits Poecile palustris under laboratory conditions

Abstract

Scatter hoarding birds are known for their accurate spatial memory. In a previous experiment, we tested the retrieval accuracy in marsh tits in a typical laboratory set-up for this species. We also tested the performance of humans in this experimental set-up. Somewhat unexpectedly, humans performed much better than marsh tits. In the first five attempts, humans relocated almost 90 % of the caches they had hidden 5 h earlier. Marsh tits only relocated 25 % in the first five attempts and just above 40 % in the first ten attempts. Typically, in this type of experiment, the birds will be caching and retrieving many times in the same sites in the same experimental room. This is very different from the conditions in nature where hoarding parids only cache once in a caching site. Hence, it is possible that memories from previous sessions will disturb the formation of new memories. If there is such proactive interference, the prediction is that success should decay over sessions. Here, we have designed an experiment to investigate whether there is such memory interference in this type of experiment. We allowed marsh tits and humans to cache and retrieve in three repeated sessions without prior experience of the arena. The performance did not change over sessions, and on average, marsh tits correctly visited around 25 % of the caches in the first five attempts. The corresponding success in humans was constant across sessions, and it was around 90 % on average. We conclude that the somewhat poor performance of the marsh tits did not depend on proactive memory interference. We also discuss other possible reasons for why marsh tits in general do not perform better in laboratory experiments.

Predictably harsh environment is associated with reduced cognitive flexibility in wild food-caching mountain chickadees

“…The initial argument (Clayton & Krebs 1994) was that non-caching species might remember both rewarded and non-rewarded locations equally well, resulting in higher memory load and hence higher proactive interference, while food-caching species were suggested to form strong memories specifically of rewarded locations, resulting in less proactive interference. Direct tests of this hypothesis found equivocal results (Hampton & Shettleworth 1996;Hampton et al 1998;Urhan & Brodin 2015). For example, Hampton et al (1998) reported more proactive interference in a food-caching species, which was associated with better memory of previous locations, just as in our study.…”

“…Highly specialized Clark's nutcrackers (Nucifraga columbiana) have also been shown to exhibit proactive interference (Lewis & Kamil 2006). Urhan and Brodin (2015) failed to detect proactive interference in marsh tits (Poecile palustris). In their paradigm birds recovered their food caches at each trial and did not need to remember specific rewarding locations in subsequent trials.…”

Evidence against observational spatial memory for cache locations of conspecifics in marsh tits Poecile palustris

“…Also, we have tested marsh tits in various food-hoarding experiments before in the same laboratory (Brodin and Urhan 2013; Urhan and Brodin 2015) and, during these experiments, marsh tits were highly motivated to both store and retrieve food. Moreover, they were able to memorise positions of their own caches.…”

Experimental Endozoochory of <b><i>Cannabis sativa</i></b> Achenes

“…However, songbirds occasionally swallow hemp achenes whole without cracking them [24,[28][29][30]. Some species temporarily hold hemp achenes in their beaks, and scatterhoard the achenes in hiding places -documented observationally [31][32][33] and in experimental studies [34,35].…”