From the past to the future: natural sound recordings and the preservation of the bioacoustics legacy in Portugal.

The preservation of historical and contemporary data safeguards our scientific legacy. Bioacoustic recordings can have historical as well as scientific value and should be assessed for their conservation requirements. Unpreserved bioacoustics recordings are generally not referenced and are frequently at high risk of loss by material degradation and/or by misplacement. In this study we investigated the preservation status of sets of natural sound recordings made in Portugal from 1983 until 2010 inclusive. We evaluated the recordings on the basis of their rate of loss, the degree to which unpreserved recordings could be preserved, and their risk of loss. Recordists of animal sounds were surveyed (by questionnaire or interview) to identify sets of recordings and to collect information on their quality and state of preservation. Of the 78 recordists identified, we found that 32% of the recordings have an unclear status and that only 9% of the recordings are lost. Of the c. 6 terabytes of unpreserved sound recordings discovered, an estimated 49% were recoverable. Moreover, 95% of the recoverable sets of recordings were at high risk of loss by their being misplaced. These risks can be minimized if recordists are persuaded to deposit their material in an institution committed to long-term curation of such data (e.g. sound archives). Overall, the study identified a considerable body of unpreserved animal sound recordings that could contribute to our scientific heritage and knowledge of the biodiversity found in Portugal. It highlights the need to implement effective policies to promote the deposit of recordings for preservation and to reverse the present scenario so that scientific material can be preserved for future generations.