Conservation of chiropters and invertebrates in volcanic cavities

PROJECT DESCRIPTION

BACKGROUND

One of the more striking geological formations on the Canary Islands are the lava tubes, which are also of great anthropological, palaeontological and biological interest. They harbour unique life forms, e.g. 13 genus and 120 species of endemic invertebrates. In addition, the lava tubes targeted by this LIFE project are a habitat for some bat species of great interest such as Plecotus teneriffae and Barbastellus barbastellus.

There is a pressing need to integrate these cavities into land use planning, given how sensitive they are to external factors such as infiltration of waste water and pesticides or degradation of the vegetation. Another factor which contributes to their degeneration is the impact of visitors.

OBJECTIVES

The main objective was to lay the foundations for an appropriate management in favour of the conservation of the lava tubes of the Canary Islands and the species dwelling there. The specific objectives were protecting the 15 most frequented tubes by installing fences and barriers, setting up a wardening service and studying the distribution and habitat requirements of the species.

An inventory and analysis of the principal threats to each site where bats and invertebrates occur was to be made, in order to draft proposals to improve their conservation status.

Knowledge of these unknown habitats was to be improved amongst the authorities, the wardens and the nature conservation entities.

Aimed at implementing a conservation management of the tubes, a study work to prevent the infiltration of waste water in one of the most important tubes (Cueva del Viento) was foreseen, as well as taking into account the presence of tubes in the management planning of the protected nature reserves containing them.

RESULTS

The foundations for the conservation of the Canarian lava tubes and their singular species were laid thanks to this project, and the difficulties to protect these insufficiently known and barely understood habitats were fairly overcome; therefore the general objective was met. The management measures and the scientific and technical work carried out in this project set solid bases to draft and implement adequate management measures for these fragile habitats and their dwelling species. This will allow that the design of protected area networks take into account the presence of these caves, hence contributing to implement an adequate management of the Natura 2000 network.

The main measures implemented in the project were:

The installation of protective gates in 9 lava tubes and the upholding of the gates of caves that were already protected are to be highlighted. The protective measures focused mainly on prominent caves with valuable natural features that were subject to human pressure, so that at the end of the project 14 of the most significant Canarian tubes were physically protected. As this kind of safe mechanisms are sometimes unpopular and subject to wreckage, some interesting alternative measures, initially not foreseen, were tried, such as blurring the hints about the presence of certain caves (pathways, tracks, indications) to ease their integration in the local landscape and make their detection difficult.

Also, the installation of informative signposts, the closure of trails with barriers to avoid the access to caves and the closure of secondary mouths to better control the access were tried with significant success.

A reinforced surveillance complemented the above mentioned protective measures. Two wardens were hired and equipped to survey the caves of Tenerife and El Hierro Islands. A reduction in the activity of potentially harmful groups (of tourists, cavers, etc) and a lower frequency of inadequate use was recorded as a consequence of their work. Complementing this specific surveillance and to continue with it after the project, all the staff related to cave management and, particularly, the wardens belonging to the official corps (regional wardens, national corps) were trained in cave conservation issues. As a consequence, they improved their attention towards these habitats, as shown by an increase in the number of reports received from them. Other authorities, such as the Teide National Park managers, committed themselves to monitor more tightly the public use in the caves under their competency.

A very good research work was done to improve the knowledge about the status of the lava tubes and the threats they were subject to, thus filling an important knowledge gap as regards these habitats of Community interest. Among the main findings, about 20 new species were described, and a critical update on the distribution of some 120 endemic invertebrate species was generated. Also, a lot of valuable information was collected about the Canarian bat populations and their use of the subterranean habitats. The tubes revealed as an important biodiversity hotspot for the European natural patrimony that should receive special attention in the framework of Natura 2000 in order to guarantee their conservation.

One of the main products generated as a compendium of the works mentioned was the “Catalogue of the Caves Important for Fauna in Tenerife, El Hierro and La Palma”. A database of the 60 most important caves identified, containing information about the location, degree of protection, biological features, threats, management measures implemented, conservation status and management recommendations. All this information was incorporated to the Regional Biodiversity Bank, a very important initiative of the Canarian Government that will be essential for the management planning of the Natura 2000 network in the archipelago.

Another important achievement was the preparation of a pilot document on integral management of full basins draining into the caves, through a work called Audit of the Leaks into the “El Viento - Sobrado” Cave System. Following a very complete study that analysed the leaks and the sources of wastewater, agro-chemicals, dangerous products and urban waste into the longest cave system of the Canary Islands, a proposal of solutions and technical management recommendations and a study of economic viability were proposed, thus creating a valuable strategy for action aimed at removing the threats for this cave. The results of the study were disseminated among the main competent authorities (local, water managers, Cabildo - island administration -, etc.), which started to prepare a project and to seek funds to implement corrective measures and stop the threats identified. The awareness raising of the administration managers had a very high impact, and the future implementation of this project would be an important step for sustainable development, with a very important socio-economic impact.

A series of excellent quality awareness raising materials were produced. An output to highlight in this regard is a video film of superb quality that was produced and internationally distributed, which is available in 2 languages (Spanish and English). There is also a monograph book of very high quality, which is a primer to the rare environments focused by the project. The beneficiary carried out a very satisfactory networking activity with other LIFE-Nat projects and, in general, with cave ecosystems specialists worldwide.