Foraging behavior of tagged rock ants (Temnothorax rugatulus)

Technological advances continue to push the boundaries of scientific inquiry in animal behavior. One such development is the emergence of automated tracking systems, which enable the collection of high-resolution spatio-temporal information for animals. Although tag-based tracking systems provide valuable insights into animal movement and collective behavior, the attachment of devices can have detrimental effects in some cases. Here, we investigated the effects of recently developed miniature tracking tags using the rock ant, Temnothorax rugatulus, as a model system. To do so, we compared the foraging activities of tagged ants and untagged ants (who lost their tags) within initially fully-tagged colonies. Additionally, we compared the foraging activities of these initially fully-tagged colonies with those of no-tag control colonies (no one was tagged). We found that tags did not significantly reduce individual activity, with tagged ants visiting the food source as frequently as untagged ants within initially fully-tagged colonies. However, our analysis revealed a marked difference in recruitment behavior—tagged ants were less likely to participate in tandem runs than untagged ants. Furthermore, the number of tandem runs was higher for the no-tag control colonies than the initially fully-tagged colonies, in which 69–95% of colony members had tags. Our data suggest, for the first time, that tracking tags can negatively impact ant behavior. Although tracking devices are powerful tools for understanding complex behavioral patterns, it is crucial to carefully consider their potential impact on animal behavior to ensure accurate conclusions.

Methods
Three colonies of ants were tagged prior to foraging experiments (Initially Fully-Tagged: 'R2119', 'R2111', and 'R2100'). However, the final proportion of tagged individuals varied since tags were frequently detached during grooming and handling. Three colonies were never tagged and served as control groups (Not-tagged: 'FR2217', 'FR2218', and 'FR2220').

For 5 hours and 30 minutes, we annotated videos (S1 Video Repository), recording the status (column: "tag_status") of each ant ("tagged" or "untagged") and time of occurrence for three foraging events:

Feeding at food source ("Feeder visit")
Leading a tandem run ("Tandem-running leader")
Following a tandem run ("Tandem-running follower")