"It is becoming increasingly difficult to find reviewers"-myths and facts about peer review.

A frequent complaint of editors of scientific journals is that it has become increasingly difficult to find reviewers for evaluating submitted manuscripts. Such claims are, most commonly, based on anecdotal evidence. To gain more insight grounded on empirical evidence, editorial data of manuscripts submitted for publication to the Journal of Comparative Physiology A between 2014 and 2021 were analyzed. No evidence was found that more invitations were necessary over time to get manuscripts reviewed; that the reviewer's response time after invitation increased; that the number of reviewers who completed their reports, relative to the number of reviewers who had agreed to review a manuscript, decreased; and that the recommendation behavior of reviewers changed. The only significant trend observed was among reviewers who completed their reports later than agreed. The average number of days that these reviewers submitted their evaluations roughly doubled over the period analyzed. By contrast, neither the proportion of late vs. early reviews, nor the time for completing the reviews among the punctual reviewers, changed. Comparison with editorial data from other journals suggests that journals that serve a smaller community of readers and authors, and whose editors themselves contact potential reviewers, perform better in terms of reviewer recruitment and performance than journals that receive large numbers of submissions and use editorial assistants for sending invitations to potential reviewers.