The power of community science to quantify ecological interactions in cities

Breanna J Putman,Enjie Li,Riley Williams,Gregory B Pauly

doi:10.1038/s41598-021-82491-y

Abstract

Studying animals in urban environments is especially challenging because much of the area is private property not easily accessible to professional scientists. In addition, collecting data on animals that are cryptic, secretive, or rare is also challenging due to the time and resources needed to amass an adequate dataset. Here, we show that community science can be a powerful tool to overcome these challenges. We used observations submitted to the community science platform iNaturalist to assess predation and parasitism across urbanization gradients in a secretive, ‘hard-to-study’ species, the Southern Alligator Lizard (Elgaria multicarinata). From photographs, we quantified predation risk by assessing tail injuries and quantified parasitism by counting tick loads on lizards. We found that tail injuries increased with age and with urbanization, suggesting that urban areas are risky habitats. Conversely, parasitism decreased with urbanization likely due to a loss of hosts and anti-tick medications used on human companion animals. This community science approach generated a large dataset on a secretive species rapidly and at an immense spatial scale that facilitated quantitative measures of urbanization (e.g. percent impervious surface cover) as opposed to qualitative measures (e.g. urban vs. rural). We therefore demonstrate that community science can help resolve ecological questions that otherwise would be difficult to address.

Highlights

Presence, leading to relatively safe habitats for prey[13]
One study found that urban anole lizards in Puerto Rico had significantly more tail breaks than anoles living in natural areas, suggesting urban habitats are riskier than natural ones, but this is the only study of this kind[31]
We collected more data on a secretive species and at a faster pace than would be possible using traditional field methods. This type of study would have been limited without the use of community science data because (1) the focal species is secretive and has low detectability through traditional field surveys, (2) most urban sites in Southern California and elsewhere are private property and not accessible, and (3) the costs associated with the time, personnel, and money needed to perform adequate data collection across a gradient of urbanization intensities would be relatively high

Summary

Introduction

Presence, leading to relatively safe habitats for prey[13]. Many urban animals, suffer serious predation by human companion animals such as owned or feral cats and dogs[14,15,16]. We chose Southern Alligator Lizards as our focal species because they are infrequently observed relative to distributed diurnal lizards and difficult to study using traditional field methods. They are a solitary, secretive species found in both natural and urban habitats in the western United States and Mexico, and they generally avoid basking, preferring cooler temperatures and spending their time under logs, rocks, surface cover, vegetation, and other dark, moist microhabitats. Because the final hosts for adults of this tick species are large mammals, which are generally lower in abundance in urban areas (e.g. deer) or are treated with anti-tick medications (e.g. dogs and cats), we expected to see the prevalence and intensity of ectoparasite infections decrease with urbanization

Methods

Results

Conclusion