COS 224-3 - Comparing direct observations and remote approaches to studying foraging behaviour across scales

Background/Question/Methods

The seeking out and acquisition of resources is essential to the survival and fitness of all species. Classical ethological methods of studying foraging behaviour provide great detail and proximate information about the selection and consumption of different food resources, but are limited to the spatial and temporal extent over which direct observations can be made. Remotely sensed approaches, comprising both spatial data from telemetry as well as various biologgers recording other data modalities beyond location, serve as a complementary lens through which to study foraging behaviour. I analyzed 604 studies of foraging behaviour across terrestrial vertebrates to compare how various research methods differed in their spatial and temporal scales, and the type and degree of inference made possible by each method. There was substantial diversity within the category of “remote” approaches, leading me to reject the dichotomy of direct observation vs. remote methods and classify five distinct approaches to studying foraging behaviour along a spectrum of direct to further removed observations.

Results/Conclusions

The spatial extent of studies using remote spatial approaches and biologgers greatly exceeded that of direct observations, but the temporal scales were comparable across approaches. When considering foraging behaviour as a process of sequential stages (habitat selection, search processes, and active consumption), direct observations predominantly focused on the most proximate level, whereas a remote spatial approach tended to be more informative at the broader level of habitat selection preceding fine-scale decision making and consumption. In addition to the range of scales over which each approach was applied, different approaches carried their own assumptions and limitations in terms of the inferences drawn. No study of foraging behaviour obtained perfect knowledge at every scale; I present a conceptual model wherein different research approaches act as imperfect lenses through which we can observe only a portion of the complete spectrum of foraging behaviour. Studies combining complementary approaches when answering questions provided the clearest and most substantive insights into foraging behaviour.