The study and importance of altitudinal migration has attracted increasing interest among zoologists. Altitudinal migrants are taxonomically widespread and move across altitudinal gradients as partial or complete migrants, subjecting them to a wide array of environments and ecological interactions. Here, we present a brief synthesis of recent development and suggest future directions towards a more taxonomically inclusive comparative framework for the study of altitudinal migration. Our framework centers on a working definition of altitudinal migration that hinges on its biological relevance, which is scale-dependent and related to fitness outcomes. We discuss linguistic nuances of altitudinal movements and provide concrete steps to compare altitudinal migration phenomena across traditionally disparate study systems. Together, our comparative framework outlines a ‘phenotypic space’ that contextualizes the biotic and abiotic interactions encountered by altitudinal migrants from divergent lineages and biomes. We also summarize new opportunities, methods, and challenges for the ongoing study of altitudinal migration. A persistent, primary challenge is characterizing the taxonomic extent of altitudinal migration within and among species. Fortunately, a host of new methods have been developed to help researchers assess the taxonomic prevalence of altitudinal migration—each with their own advantages and disadvantages. An improved comparative framework of altitudinal migration will allow researchers that study disparate disciplines and taxonomic groups to better communicate and to test hypotheses regarding the evolutionary and ecological drivers underlying variation in altitudinal migration among populations and species.

We used the program Publish or Perish (Harzing 2007) to quantify temporal trends in Google Scholar hits for publications that use the terms “altitudinal migration” and “elevational migration”. We removed any articles from this data set that did not refer to seasonal movements of organisms across altitudinal gradients. We removed any articles from this data set that did not refer to seasonal movements of organisms across altitudinal gradients. Although both terms received some extraneous and duplicate hits, we found that altitudinal migration was established as a term far earlier and has been used far more often than “elevational migration” (Figure 3).  Specifically, we recovered 2228 Google Scholar search hits for “altitudinal migration” compared to 335 for “elevational migration” (searches done on 15 August 2023). Also, the term altitudinal migration is more established across reviews and papers that explicitly define this phenomenon (Table 1). Using this data set, we also calculated the log-linear model of publication growth rate for both “altitudinal migration” and “elevational migration”. We found that “altitudinal migration” has an estimated growth rate of 5.51%, whereas “elevational migration” has a growth rate of 10.34% (see Supplemental Material for R Code). Growth rates for both terms are higher than what has been estimated for all sciences (4.10%; Bornmann et al., 2021) and for the life sciences (5.07%; Bornmann et al., 2021), indicating strong interest in this field of research.