Monday January 24, 2022
The meticulous records of biologists and naturalists that are decades or even centuries-old provide an invaluable window into the past. With the advent of modern analytical techniques, field notes and specimens from expeditions long ago are increasingly serving as time capsules. These historic data allow modern scientists to better understand how environments and animal populations have responded to factors like climate change and human development. For example, thanks to the work of one industrious avian enthusiast more than a century ago, scientists at UC Berkeley have unlocked a treasure trove of insights into how bird and mammal populations throughout the state of California have shifted and changed (Iknayan and Beissinger 2020).
In 1908, Joseph Grinnell became the first director of the newly created Museum of Vertebrate Zoology at UC Berkeley. For the next thirty years (1908–1939), he and his team traveled to 700 different sites across the state of California to conduct bird and mammal surveys. In addition to the 100,000 mammal and bird specimens collected for the museum, Grinnell and his field crew took 74,000 pages of notes and 10,000 photographs. This wealth of knowledge sat largely undisturbed on a shelf until 2004, when UC Berkeley ornithologist Steve Beissinger undertook a project to revisit Grinnell’s field sites. This work has taken over ten years to complete, and has required careful review of the location information associated with museum specimens, as well as site descriptions taken from field notes, in order to relocate the areas where the original surveys were conducted more than 100 years ago.
Modern surveys were conducted at the rediscovered sites with the intention of evaluating changes to the abundance and diversity of mammal and bird species. Grinnell and his colleagues didn’t have the benefit of modern equipment like handheld GPS units and modern computing technology. However, newly developed statistical modeling approaches are able to incorporate the data from their exhaustive notes and specimens with contemporary data in order to paint a more complete picture of the changes these natural communities have experienced. The project’s findings have revealed interesting insight into the response of bird communities to climate change, some of which challenge commonly held assumptions. For example, although it is often maintained that desert birds will shift their ranges northward and alpine species will simply move to higher elevations to adapt to a changing climate regime, these patterns did not hold true in many of the assessed sites. The knowledge that simply moving to better habitat may not be feasible for many species is important for informing approaches to management and conservation efforts.
The face of California has changed dramatically since Grinnell and his contemporaries explored its deserts, mountains, and wetlands. Many of the landscapes we know today, such as the sprawling cityscape of Los Angeles and the leveed cropland of the Central Valley, were just beginning to be developed when Grinnell’s surveys were conducted. Therefore, the insight they provide may act as a valuable baseline against which to compare modern data on natural communities throughout the state. The project of reevaluating Grinnell’s data is ongoing, and the next step will be to conduct a statewide analysis that pools the data collected on all the different species that were evaluated. The hope is that this effort will provide an understanding of how each species has responded to the changes of the past century and will help identify factors that may be contributing to population declines. Read more about how FISHBIO also conducts bird surveys as part of our work.
This post was featured in our weekly e-newsletter, the Fish Report. You can subscribe to the Fish Report here.