Author self-citations in the field of ecology

Ecologists writing research articles frequently cite their own papers. Self-citations are frequent in science, but the reasons behind abnormally high rates of self-citations are questionable. My goals were to assess the prevalence of author self-citations and to identify the combination of attributes that best predict high levels of self-citations in ecology articles. I searched 643 articles from 9 different ecology journals of various impact factors for synchronous (i.e., within reference lists) and diachronous (i.e., following publication) self-citations, using the Web of Science online database. I assessed the effect of the number of authors, pages, and references/citations, the proportion of diachronous/synchronous self-citations, and the impact factor, on the proportion of synchronous and diachronous self-citations separately. I compared various candidate models made of these covariates using Akaike’s Information Criterion. On average, ecologists made 6.0 synchronous self-citations (12.8% of references), and 2.5 diachronous self-citations (25.5% of citations received 2.8 to 4.5 years after publication) per article. The best predictor of the proportion of synchronous self-citations was the number of authors. My study is the first to report recidivism in the inclusion of self-citations by researchers, i.e., the proportion of diachronous self-citations was best explained by the proportion of synchronous self-citations. The proportion of self-citations also increased with the number of pages and the impact factor of ecology journals, and decreased with the number of references/citations. Although a lot of variance remained unexplained, my study successfully showed regularities in the propensity of ecologists to include self-citations in their research articles.