Especificaciones de evaluación relacionadas con las dimensiones de la competencia profesional

6.6.1 The role of Protected Areas

This thesis has demonstrated that, as species have undergone distributional changes, PAs can (1) facilitate colonisations, (2) resist non-native species, and (3) provide appropriate

environments for species in global decline. As such, they contribute to AICHI Target #9 (by preventing the spread of non-natives within a country, if not necessarily preventing initial introduction), AICHI Target #12 (preventing the extinction of known threatened species) and parts of UN Sustainable Development Goal #15 (protect and prevent the extinction of

threatened species). PAs (see Introduction) are most likely to be designated for the presence of a species, species assemblage, or high numbers of individuals. When PAs do contain

threatened species (e.g. the SGBR’s core protected areas), they remain of current relevance for those species for which they have been designated. In this context, however, the future relevance of PAs has been questioned, given that the distribution of species are shifting as a result of climate change and other factors. If the climatic requirements of Military Macaws and Bearded Wood Partridges soon fall outside of the SGBR’s core protected areas, their value will have been reduced. The challenge here is that PAs may cease to meet some of the original reasons for their designation, even if they facilitate colonisations of new species and resist non-natives. These colonisations demonstrate that PAs will continue to be important as the distributions of species shift in response to climatic and other drivers. In this respect, the intention to increase the coverage of PAs to 17% (AICHI Target #11) or beyond (e.g. Dinerstein

et al., 2017) is an important conservation goal. However, designations will need to be

sufficiently flexible to accommodate changes in the composition of the biota in any specific PA. Increased coverage of PAs, however, may be difficult to achieve due to competition for land resources, which have historically biased PA land towards relatively unproductive

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continued achievement of conservation targets. More than 50% of Mexico’s land is part of an ejido – communal agricultural land which has been typically characterised by unsustainable resource use, high poverty, and restrictions on land transfer (World Bank, 2001). As such, acquisition of land for PAs is difficult, especially given the competition for available land provided by economically more attractive alternatives such as the development of the tourism industry. In the south-east of Mexico, tourism is now the most important economic activity in Quintana Roo (Barsimantov et al., 2009), and in the north-west it is the major contributor to the local economy of many parts of Baja California (Angeles et al., 2009). Whilst tourism development and protection for conservation might come into conflict (Saarinen, 2016), the growth of nature- and eco-tourism activities such as whale-watching (Brenner et al., 2016) provide an environmentally more-stable, and increasingly economically viable alternative to competing economic activities like gillnet fishing (associated with the decline of the Vaquita

Phoecena sinus; D’Agrosa et al., 2000).

When land is designated as a PA, the level of protection and the degree to which the protection is enforced will determine its ‘effectiveness’. In the SGBR, the levels of micro- disturbance that I observed were similar in areas with buffer protection (IUCN Category VI) and unprotected areas. The core protected areas that I visited were largely free from macro and micro-disturbance, although this should be considered in context as well. The core zones that I censused were in remote, inaccessible locations, and were regularly patrolled by rangers. This is not the case with all of the core protected areas in biosphere reserves across Mexico (Roberto Pedraza pers. comm), some of which are affected by illegal logging and hunting. The authorities which run the reserves do not have enough resources to

comprehensively patrol the boundaries of each of the core areas. When this happens, the value of PAs may be reduced by a lack of conservation enforcement. In such cases, their ecological effectiveness, particularly in terms of protecting vulnerable species, might be reduced. Nevertheless, in a global analysis which included many countries that have been associated with ‘paper parks’, PA coverage was still associated (Tables 5.3, 5.4, 5.5) with reduced extirpations and increased colonisations.

6.6.2 Non-native Species

Non-native species are those which have taken advantage of human ‘assistance’ to colonise novel regions. The drivers of non-native species richness (trade, human population density;

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Table 5.5) are unlikely to disappear soon, and so the growth of non-natives will continue. Comprehensive culls of non-native species may be effective, on occasion, depending on population size and other factors. For example, because of fears of hybridisation with endangered White-headed Ducks, the Ruddy Duck population of Europe has been controlled (Henderson, 2010) and they have now largely been eradicated from the UK (Holling et al., 2014). PAs might act as another measure in resisting the spread of non-native species. In the UK, non-native wetland birds were initially absent from PAs in recently colonised counties. In Mexico, core protected areas were free of non-natives, and globally, countries with more protected land had fewer introduced species. Yet the reasons for this resistance might vary between regions and between species. UK PAs were increasingly vulnerable as the

populations of non-native wetland birds grew, perhaps because the ‘release point’ of non- natives has tended to be in human-modified environments. Mexican core PAs might have been free of non-natives because of their geographic isolation from ‘establishment centres’ of non-natives in Mexico (although for those species spreading from the USA, core PAs are equally as remote as disturbed parts of the landscape). Alternatively, the lack of disturbance in core zones meant that there were fewer opportunities for non-natives species, which in the SGBR were largely found in human-modified environments. Attempts to control the spread of non-native species must, therefore, be context dependent.

The default conservation position on non-native species should also be considered. Non-native bird species in the UK, Mexico and across most of the world rarely pose direct threats to other bird species (Table 1.3). The case of the Ruddy Duck is apparently an exception, rather than the rule. In contrast, non-natives add to the alpha-diversity of the regions which they occupy, and in this respect are a positive component of distributional change (the presence of non-native birds has numerically compensated for the loss of native species in most countries across the World, resulting in a typical increase in national alpha diversity of about 1.5%). The range of species found on British wetlands and disturbed Mexican forest and scrub is higher as a result of non-natives. The spread of species such as Black Swans into British wetlands is welcomed with considerably less enthusiasm than, for example, the Great Egrets which have recently colonised the south of the country. Yet, just as House Sparrows (now a protected and much-loved ‘native’ species in many European

countries) did 5,000 to 10,000 years ago (Thomas, 2017) and Collared Doves did 60 years ago, both species are opportunists taking advantage of human-induced actions. In these examples, the species took advantage of human-modified habitats, whereas others have benefitted from their ability to escape from bird collections or to respond to changed climates. To add another

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layer of moral confusion, whilst many parties are preoccupied with the removal of non-native species, the population of Common Pheasants (native to Asia) and other game species is artificially augmented each year in the UK and many parts of the World to provide sport for hunters. Game management is not universally positive, of course, but such effects (for example, predator management) are not restricted to non-native gamebirds.

Although their status and life histories differ, each of the above species have made the British breeding bird avifauna richer than it was before their arrival, and perhaps should not be viewed through a lens which is, by default, negative.