Leveraging data from 6,645 camera traps throughout the United States, scientists examined the populations of 25 mammal species. Their findings revealed that climate plays a more significant role than human activities in determining where mammals choose to inhabit.
Despite the substantial impact of human activities on the environment, a recent study by North Carolina State University indicates that climate remains the foremost factor affecting the survival of mammal species. This research provides important insights into the implications of climate change for wildlife populations.
Roland Kays, the lead author of the study, explained that the aim was to assess the relative importance of climate against human influences in mammal habitation. To achieve this, researchers gathered data on 25 different mammal species from 6,645 sites across the United States. This research represents one of the largest analyses of camera trap data undertaken to date. Most of the data originated from Snapshot USA, a national mammal camera trap survey conducted in collaboration with various partners nationwide.
“Initially, we hypothesized that human alterations to the landscape might make us the primary influencers on animal distribution,” noted Kays, a research professor at NC State and a scientist at the N.C. Museum of Natural Sciences. “However, our findings revealed that climate factors, including temperature and precipitation, were actually the predominant influence for most of the species we examined.”
Nonetheless, human influences such as large urban areas and agricultural activities also played a notable role in mammal distribution. While some species struggled in urban settings and near farmlands, others adapted well to these environments. Kays pointed out, “Many species thrive in human-populated areas. For example, the Eastern gray squirrel is very common in Raleigh and flourishes alongside people. In contrast, the Eastern fox squirrel thrives around agricultural settings, but not so much in urban areas.” He added, “These differences are evident in various species, such as the snowshoe hare, which does not fare well around urbanization or agricultural zones. This study highlights the species that are more affected by human activity, as well as those that benefit from it.”
This research enabled scientists to develop maps that predict the prevalence of different mammals across the contiguous United States, effectively categorizing the country into areas defined by the types of mammals that are prevalent in each. These areas, referred to as ecoregions, are typically used in plant research but have not been previously applied to mammalian populations.
“For example, the Eastern deciduous forest is classified as an ecoregion based on the commonality of certain trees,” Kays said. “We can now apply this method to mammal species and compare it with plant ecoregions. Our findings showed a remarkable similarity between the two, as regions in the east with higher rainfall supported greater plant growth, which in turn corresponded with a higher abundance of mammals due to the increased food availability.”
The open-access article, “Climate, food and humans predict communities of mammals in the United States,” can be found in Diversity and Distributions. By recognizing climate as the primary factor influencing mammal habitat selection, this study introduces a valuable resource for anticipating how climate change will affect mammal populations. The increase in global temperatures could result in shifts in where animals can reside, as well as changes in precipitation patterns and plant growth. Understanding these elements will be crucial for sustainable management decisions regarding mammal populations moving forward.
