Covid-related surge in global wild bird feeding: Implications for biodiversity and human-nature interaction

Our results show clearly that interest in bird feeding is more common around the globe than previously understood [25]. Bird feeding has historically been characterized as concen- trated in Anglophone countries, including the United States, United Kingdom, and Australia, as well as in India, where it aligns with cultural practices. Indeed, the earliest recorded refer- ence to bird feeding is likely in Hindu writings of the Vedic era, from over 3,500 years ago ([1]: 39). These countries occur in our sample, along with many other countries spanning six continents. Variations in bird feeding across countries may be driven by cultural, geographic, or eco- logical reasons and is an important area of future research. In addition to cultural practices in the Indian subcontinent described above, bird feeding practices may be related to winter con- ditions. For example, bird feeding is more common in Northern Europe than in Southern Europe, and it remains a mostly winter-only activity in Northern Europe [1]. Indeed, there is a strong association between countries with a bird feeding policy and colder minimum tempera- tures [27]. However, we also found that bird feeding occurs in both the northern and southern hemispheres despite lockdowns occurring from February to April 2020, which is spring for the northern hemisphere and fall for the southern hemisphere. Bird feeding extent appears to have a wider occurrence than that described in Baverstock et al. [27], which used countries’ bird feeding policies as a proxy for bird feeding interest.

Beyond geography, bird feeding frequency may depend on socioeconomic factors. Bird feeding requires resources to share food with birds or money to buy commercial bird seed, as well as markets that supply commercial bird seed and bird feeders. Patterns of settlement within countries, including having access to parks, a balcony, or a backyard, can make bird feeding more accessible. Finally, as explored in the next section, it is possible that there are eco- logical features or settings that make bird feeding more enjoyable. This could include greater returns to watching birds feed and interact when doing so within a more biodiverse habitat or viewing a greater variety of species that visit a feeder. Though the scope of feeding found by our study is wider than that of previous studies, our analysis has an important limitation. Our list of countries is likely biased toward those with higher incomes and better internet access, e.g., countries with lower income or less internet access may have de facto lower search intensity for bird feeding, despite local bird feeding practices. We may not be able to document this bird interest due to our measure of bird feeding, Google search intensity. The extent of bird feeding presented here may there- fore be an underestimate. Despite this limitation, however, the distribution of bird feeding interest discovered in the present study demonstrates clearly that interest in bird feeding is not limited to traditional locations such as the United States, United Kingdom, Canada,

Germany, and Australia [1]. Even given the limitations of our measure, among countries with high search interest, we identify some with low income and low internet access, such as Kenya and Pakistan. We encourage future work to consider how global bird feeding affects bird populations. b. Species richness predicts bird feeding interest Next, we explore whether a country’s local interest in bird feeding is associated with its avian diversity. Fig 2 Panel B shows the existence and absence of search interest for bird feeding across countries or regions using the cross-sectional search intensity data, and Panel C shows how bird species richness, the total number of bird species recorded in that country, varies across the globe. The t-test results in Table 1 indicate that countries with an absence of search interest intensity had a mean of 294 (SD = 288.6) species, while countries with existence of search interest had 511 (SD = 400.5) species. This difference is statistically significant. PLOS ONE Covid-related surge in global wild bird feeding PLOS ONE | https://doi.org/10.1371/journal.pone.0287116 August 2, 2023 8 / 15