Author response to "Comments on “Clear-cuts and warming summers caused forest bird populations to decline in a southern boreal area” by Virkkala et al. " by Vauhkonen

Abstract

In his correspondence, Vauhkonen (2025) argues that our analysis indicating a significant effect of clear-cutting on the decline of forest bird populations is misleading because of the use of cumulative clear-cuts as an explanatory variable in the model. He has reanalysed our bird census data by including annual clear-cuts in different analyses. Here, we reply to Vauhkonen’s critique and show that annual clear-cuts cannot be used as an explanatory variable because they do not take account of the long-term effects of clear-cuts. Annual clear-cuts cover only 1.4 % of the study area, on average (7.5 ha/564 ha). Such a small proportion of the landscape cannot, on its own, affect bird population densities yearly across the whole study area during the 30-year study. In contrast, as most of the abundant bird species prefer forests with a mean stand height of over 10 m, clear-cuts have long-lasting negative effects on boreal bird populations that accumulate across several years or even decades. This effect is ignored in the models by Vauhkonen (2025), rendering them ecologically irrelevant. We conclude that our approach of using cumulative clear-cuts is well-founded for analysing the effects of clear-cuts on bird populations. Other factors criticized by the author, such as aging of the observer and the use of Global Forest Change data in measuring clear-cut cover, do not cause deviations to the original results presented by us.