That natural cliffs offer valuable habitats for many birds is widely recognized and cliffs are often protected. But cliff-nesting birds readily use habitats created by human activities, such as quarries to breed, rest or soar, riding the rising hot air above sunlit slopes. Such areas become more important as natural habitats of many birds are disappearing. But nature managers sometimes undervalue industrial sites as potential habitats. Why?
We continue our theme on land forms following a previous post on geomorphologic design. This time we talk about cliffs and the topic is presented by guest blogger Zoë Rohrer, ecological restoration professional from Spain.
Quarrying involves severe disturbances to the environment and so these areas are often disregarded by environmentalists. But more often the case is that quarries spontaneously evolve over time into areas of great natural value. Also, some species of birds, as well as other fauna, occupy cliffs even during the active life of quarries. For example, eagle owls (Bubo bubo), sand martins (Riparia riparia) and jackdaws (Corvus monedula) can be easily found in active sites. Another example, the black wheatear (Oenanthe leucura) is in decline in Cataluña but recent studies have detected flourishing populations in quarries there (Noguera et al, 2014).
The “business as usual” approach to mine restoration discourages cliffs as well. Under the influence of old legislation restoration plans often ignore important ecological aspects and valuable habitats are lost. For example, a typical restoration plan aims to eliminate or reduce cliffs, and therefore override any subsequent colonization by rupicolous species as public safety and cliff stability are major concerns in quarry restoration.
Public safety and cliff stability are major concerns in quarry restoration. However, we have the technical knowledge to create stable cliffs. For example, the method known as Talus Royal® consists of “accelerating” the natural weathering of rocks. The result are very stable cliffs, which are visually attractive and integrated into the landscape. Also, the irregular morphology promotes the colonization of flora and fauna. More information on cliff stability and ecological restoration can be found in Martín Duque et al, 2011.
In the mining life cycle the conservation end-use is regarded as a low profit activity, yet creating habitats can be less expensive than other end uses, such as agriculture. In the long run, it offers financial advantages as well. For example it can decrease the cost of post restoration management, since it avoids problems such as erosion. Conservation end-use has other added values as well: it brings biodiversity back, creates aesthetically valued landscapes, and increases public health and quality of life. A very interesting manual with guidelines on promoting rupicoulous species was published by the Spanish Foundation for Cement and Environment (CEMA, 2010).
Creating habitat for cliff-nesting birds should be approached case by case. It is not a universal recipe. But, industrial habitats offer the opportunity to enhance rupicolous birds. Managing quarries to create rocky habitats can be an opportunity to recreate a scarce habitat and to improve local biodiversity.
Zoë Rohrer is a biologist, specialized in Restoration Ecology. She is working on a project regarding the colonization of quarry walls by cliff nesting birds together with the University of Alcalá de Henares and LafargeHolcim. Her objective is to promote a more ecologically centered restoration in the mining industry.
Castillo, I., Elorriaga, J., Zuberogoitia, I., Azkona, A., Hidalgo, S., Astorkia, L., Agurtzne, I., Ruiz, F. 2008. Importancia de las canteras sobre las aves rupícolas y problemas derivados de su gestión. Ardeola 55(1):103-110.
CEMA. 2010. Manual de restauración de la biodiversidad en entornos calizos (REBECA). Fundación Laboral del Cemento y el Medio Ambiente, Madrid, España. Found online here: http://www.fundacioncema.org/Uploads/docs/Manual_Restauraci%F3n%20de%20la%20biodiversidad%20en%20entornos%20calizos%20%28REBECA%29_F.CEMA.pdf
Davies, A.M. 2006. Nature after minerals – How mineral site restoration can benefit people and wildlife: the report. The RSPB, Bedfordshire, Reino Unido.
Lundholm, J.T., Richardson, P.J. 2010. MINI-REVIEW: Habitat analogues for reconciliation ecology in urban and industrial environments. Journal of Applied Ecology 47:966–975.
Madroño, A., González, C., Atienza, JC. (eds.). 2004. Libro Rojo de las Aves de España. Dirección General para la Biodiversidad – SEO/BirdLife, Madrid, España.
Martín Duque, J.F., de Alba, S., Barbero, F. 2011. Consideraciones geomorfológicas e hidrológicas. En: Valladares, F., Balaguer, L., Mola, I., Escudero, A., Alfaya, V. (eds.), Restauración ecológica de áreas afectadas por infraestructuras de transporte. Bases científicas para soluciones técnicas, pp. 44-72. Fundación Biodiversidad, Madrid, España.
Noguera, M., Francesc, X.A., Santaeufemia, F.X. 2014. Situació del Còlit negre Oenanthe leucura al massís del Garraf i paper de les pedreres costaneres en la seva conservació. Revista Catalana d’Ornitologia 30:41-53.