This paper analyses how in the aftermath of one of the worst environmental disasters ever to occur in Spain - the Aznalcóllar Disaster - various environmentalist and conservationist groups mobilised migratory birds to bring new insights and the need for new precautions to the controversy elicited by the spill. The case study, thus, revolves around how environmentalists established a "hybrid collective action" to draw attention to unconsidered risks and impacts of the disaster and thereby make the case for open debate. Building upon this, I engage with two different, though interrelated, theoretical debates that contribute to a rethinking of environmental management (EM) as a social and materially situated practice. Drawing on the idea of "tactic" (De Certeau, 1984), I draw attention to the devices, actions and procedures that environmentalists carried out to resist attempts to minimise the spill and to undermine administrations¿ assumptions of control, coherence and singularity associated the idea of management. Drawing on Tim Ingold¿s latest work (2007, 2008, 2011), I analyse environmentalists¿ most successful tactic: the enactment of migratory birds as "lines". Together with other authors in this special issue, I will use this notion to make an argument against some of the assumptions of the "hybrid ontology". In contrast to more essentialists and static notions of non-human agency and politics, the idea of line is particularly useful as a way of understanding how nature(s) can be effectuated differently and how this leads to the imagining of new regimes of cohabitation, human and non-human management and intervention.

En este trabajo se analiza cómo durante la secuela de uno de los peores desastres ambientales producidos en España -el desastre de Aznalcóllar- varios grupos ecologistas y conservacionistas movilizaron a las aves migratorias para aportar nuevas ideas y la necesidad de nuevas precauciones a la controversia provocada por el derrame. El estudio de caso, por lo tanto, gira en torno a cómo los ecologistas establecieron una "acción híbrida colectiva" para llamar la atención sobre los riesgos e impactos no considerados del desastre y, por lo tanto, llevar el caso al debate abierto.

En aquest treball s'analitza com durant la seqüela d'un dels pitjors desastres ambientals produïts a Espanya -el desastre de Aznalcóllar- diversos grups ecologistes i conservacionistes van mobilitzar a les aus migratòries per aportar noves idees i la necessitat de noves precaucions a la controvèrsia provocada per el vessament. L'estudi de cas, per tant, gira entorn a com els ecologistes van establir una "acció híbrida col·lectiva" per cridar l'atenció sobre els riscos i impactes no considerats del desastre i, per tant, portar el cas al debat obert.