4.4.1 — Calculation of range territories by GIS intersections

The aim of GROMS was to produce an overview of the distribution of migratory species on a global scale. The set of 544 GIS maps presented here is based mainly on handbooks and 2 digital sources (for map sources and species groups covered, see Table 4.1). This data set can be intersected with any other GIS layer, for instance the political boundaries of states and provinces (administrative units). The basic concept of this operation has been sketched in Figure 3.4. The following additional steps were necessary for an intersection of the entire set of distribution maps:

1. Merging of all distribution maps to one GIS data file (allpolygons.shp),
2. Intersection of "allpolygons.shp" with administrative boundaries (admin98.shp by ESRI),
3. Import of the intersection attribute table into the GROMS database (Tab_Species_AdminStat). This table contains administrative unit name, species name and site function (e.g. breeding, feeding).

Besides mapping, the imported results can now be queried within the GROMS database, to produce species lists for each country or province, by clicking on the "species lists" button within the GROMS database main selection panel. In addition, it is now possible to list territories for each of the mapped 544 species, as part of the "species report" option (see User Guide, Annex I).⁴⁶

However, the user has to be aware that these lists are computed automatically, and therefore keep in mind the following constraints:

1. The GIS map is the basic information source, and any inaccuracy there is transmitted to the resulting lists. It is therefore important to cite the map source,
2. Boundaries and names of states and provinces are based on the ESRI data set (country.shp and admin98.shp, within ArcView 3.2 by ESRI). The designations concerning the legal status of any state or territory, their sovereigns or the delimitation of their frontiers are adopted directly from ESRI and do not reflect any opinion of the author.

Therefore, the species territories listed by GROMS are by no means identical with range state lists as used by CMS, but can certainly be used as a starting point for further comparison and investigation. The following differences require special attention: Overseas territories or autonomous areas are listed separately by ESRI, with sovereigns in a separate column. However, CMS membership of sovereigns does not necessarily mean that the Convention applies within all territories (see Figure A2.1). For example, Denmark is a party to the CMS, but the Convention does not apply throughout its autonomous territories — Greenland and the Faroe Islands (Denmark). For other countries the Convention applies throughout their overseas territories (e.g. French Overseas Territories such as Réunion or Amsterdam Island). Therefore, the GROMS database has to store CMS status on a territory base. Even so, there are some regions of unclear status (e.g. Spratley Islands), and up to now (July 2001) the CMS secretariat has been unable to inform GROMS officially about the CMS membership status of most overseas territories.

An additional complication of the range state as defined by CMS is the inclusion of "[...] states, flag vessels of which are engaged outside national jurisdictional limits in taking that migratory species" (UNEP-CMS, Art. I 1k). This requires a careful evaluation of national responsibilities within fishery zones, and an interpretation of whether the definition extends to all migratory species taken as bycatch. Be this as it may, the GIS methodology described above can certainly be applied to fishery zones and moving flag vessels. For marine organisms it would be important to know whether CMS legislation applies within the 200 nautical miles zone of marine sovereignty. For the time being, the GROMS list of "range territories" may be considered as a suggestion for improving the official CMS range state lists.

An additional range state list is maintained and was published recently in the shape of the IUCN Red List 2000 (Hilton-Taylor 2000), including current information on extinction or (re)introduction on a country level. Though not in GIS-format, this information could be integrated easily into the GROMS database as a separate column within the GROMS range territories lists. Some inconsistencies between IUCN and GROMS lists were found, which might serve as a starting point for detailed investigations or case studies (see also the discussion of local extinctions in 4.4.5, and the comparison of maps from different sources, as in Figures A2.17 and A2.49).

The maintenance of range state lists is an important and time-consuming task for conservationists. Our example shows that range states or even provinces for each species can be calculated by using GIS maps based on a well-defined data source (in this case, the reference for the distribution map). Thereby, range state information can be made more transparent. Different sources can be compared, and in the case of contradictory results, further investigations can be initiated. The advantage of "calculated administrative units" becomes even more evident in the case of provinces. In fact, the half-life of provinces is often longer than that of states. In addition, provinces are responsible for nature conservation or hunting laws in many federal states. Thus, it sometimes makes sense to analyse long-term political aspects of nature conservation at a provincial level.

This document should be quoted as part of the publication "Riede, K. (2001): The Global Register of Migratory Species ­ Database, GIS Maps and Threat Analysis. Münster (Landwirtschaftsverlag), 400 pp." + CD

 by Klaus Riede