Literature search
We compiled a list of peer-reviewed scientific publications on avian telomere dynamics from 2000 to 2020 using Google Scholar and Web of Science as online search engines. We simultaneously used “telomere”, “zebra finch”, and “birds” as keywords, including “~” in front of every word to consider also potential synonyms. A further search was performed also using the same keywords individually to cross check the comprehensiveness of our results. We performed the web search first considering the entire 20-year interval and then on a year-by-year basis. We only recorded studies published in peer reviewed journals and excluded thesis’, reviews, metanalyses and preprints. We divided our total sample into two categories: 1) telomere studies using the zebra finch, and 2) telomere studies using any species other than zebra finch. For each category we listed the studies in ascending chronological order, and for multiple publications within each year we listed authors in alphabetical order. The results of our literature search are summarized in Table 1 of Supplementary Materials.