What’s missing from this picture? Bias in connectivity research for American carnivores

A recent literature review looks at connectivity research over two decades (2000-2020), focusing on the Order Carnivora in the Americas and using search terms such as “ecological corridors” and “American carnivores.” From the resulting papers, they summarized key characteristics like study location, species, and methodology. They also compiled country-level data, such as the proportions of human-modified land and protected land, along with the Red List status of each species.

They found that the connectivity literature had widespread geographic, taxonomic, and methodological bias. Of 137 studies that met the study criteria, 74% were conducted in North America, even though almost half of terrestrial carnivores are in South America. Some of the countries with the lowest percentage of species at risk (Canada and the U.S.) were those with the most studies. Conversely, some countries with high percentages of at-risk species (Ecuador and Peru) were among those with the fewest studies. Uruguay and El Salvador, which have some of the lowest percentage of protected land, were also among the countries with the fewest studies.

There was a large taxonomic bias in favor of large carnivores: nearly half of the studies focused on felids, particularly jaguars and puma. South American foxes and other small South American carnivores were understudied, and 53% of carnivore species were not represented at all. Some small carnivores can be cryptic and difficult to study, possibly contributing to this skew. However, the absence of studies on over half of American carnivores means that researchers are likely overlooking at-risk species.

They also found that the literature favored certain analytical approaches, most commonly least-cost path analysis. However, a priori corridor definition, which doesn’t use algorithms and can be challenging at large scale, was most common in Central America. The researchers emphasized that accurate dispersal data was necessary for connectivity research, but that expensive methods (like telemetry, genetic analysis, and camera trapping) are more available in wealthier countries like the U.S. than in other parts of the Americas.

This study spotlights the importance of social factors in connectivity work. Human factors like economic inequality, language barriers, and politics affect how connectivity research is conducted (as well as how it’s published), to the detriment of some communities. While big carnivores like jaguars and pumas need attention, so do short eared foxes, eastern spotted skunks, and other often overlooked smaller animals.

Ecosystems would be better served if the tools needed to conduct research were more widely available. It’s likely that taxonomic, geographic, and methodological biases play out elsewhere in connectivity research. This could mean missing research about connectivity of microorganisms, for example, or research in or from countries which aren’t primarily English-speaking. The information gaps highlighted here will hopefully inspire future research to fill them in and improve connectivity conservation.

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