wiidfowl conservation: implications of the anseriform conservation assessment and management plan
Post on 29-Sep-2016
Embed Size (px)
I n / Zoo Yh (1994)33 114-118 0 The Zoological Society of London
Wi Idfowl conservation: implications of the Anseriform Conservation Assessment and Management Plan ANDREW J. GREEN & SUSIE ELLIS I The Wildfowl & Wetlunds Trust, Slimbridge, Gloucester GL2 7B7: Great Brituin und ?IUCNISSC Conservution Breeding Specialist Group, 12101 Johnny Cuke Ridge Rocid, Apple Vulley, Minnesota 55124, USA
Given the rate of destruction of wetlands habitat, an increasing number of wildfowl taxa are under threat. Collaboration between CBSG, the IWRB Threatened Waterfowl Research Group and The Wildfowl and Wetlands Trust has produced a first draft of a Conservation Assessment and Management Plan for Anseriformes which has resulted in the most objec- tive list of threatened species to date. Although much attention has been focused on problems of migratory waterfowl it appears that comparatively few migrants are seriously threatened. In addition to developing flyways for migrants, the development of plans for non-migratory species is urgent. A revised draft of the Plan is scheduled for late 1994.
Reduction and fragmentation of wildfowl populations and wetland habitats are occurring at a rapid and accelerating rate. For an increasing number of taxa, this has led to small and isolated populations that are at risk of extinction. As wildfowl populations diminish in their natural hab- itat, conservationists realize that manage- ment strategies to reduce the risk of species extinction must be adopted. The Wildfowl & Wetlands Trust, International Waterfowl and Wetland Research Bureau (IWRB) Threatened Waterfowl Research Group and Conservation Breeding Spe- cialist Group of the IUCN Species Sur- vival Commission are co-operating in the identification, monitoring and conserva- tion of the worlds threatened wildfowl.
The Wildfowl and Wetlands Trust has had a long-standing interest in the con- servation of Anseriformes (Anatidae and Anhimidae) threatened with global extinc- tion. In the 1930s the Trusts founder, the late Sir Peter Scott, identified the Hawai- ian goose Bruntu sundvicensis as a species in need of urgent action and went on to
establish a captive-breeding programme at Slimbridge (Scott. 1938, 1981).
In the 1970s the Trust began to identify and monitor the worlds threatened wild- fowl (Kear & Williams, 1978; Kear, 1979). Since 1989 The Trust has intensified mon- itoring of threatened Anseriformes (Green, 1992a; Callaghan & Green, 1993) and has developed recovery plans and conservation programmes for selected spe- cies (Anstey, 1989; Green, 1992b, 1993). This work has been aided by the develop- ment in 1990 of the Threatened Waterfowl Research Group which is currently co- ordinated from The Wildfowl and Wet- lands Trust.
ANSERIFORM CAMP The Conservation Breeding Specialist Group is pioneering the use of scientifi- ically based management tools that aid informed and efficient decision-making regarding allocation of limited conserva- tion resources for species management and survival. One such tool is the Con- servation Assessment and Management Plan (Foose & Seal, 1991: Foose rt ul., 1992, Seal et ul., 1994; see also Ellis, this volume). The first CAMP prepared for a bird group was for the Anseriformes and was developed in a workshop of experts from CBSG, the IWRB Threatened Water- fowl Research Group and The Wildfowl and Wetlands Trust at Slimbridge in August 199 1.
A key activity is the assignment of categories of threat to each taxon, includ- ing subspecies. It has long been recognized
AQUATIC BIRDS 115
that the original IUCN categories for threatened status are based on highly subjective criteria and are inadequate. The Mace-Lande proposals for revised and more objective criteria which could be applied across taxonomic lines (Mace & Lande, 1991) are currently undergoing further revision (Mace et ul., 1992). The original Mace-Lande criteria defining Critical, Endangered and Vulnerable (see Ellis, this volume) were systematically applied in the Anseriform CAMP.
When other factors, such as information about population fragmentation, demo- graphic trends, range, environmental sto- chasticity and commercial exploitation or interaction with introduced taxa, are taken into account taxa with populations of more than 10 000, although normally con- sidered as above the safety level, would possibly qualify for threatened status. The Baikal teal Anus formosu, for example, with a global population estimated at 40 000, is classified as Vulnerable because of its rapid and continuing rate of decline.
The Anseriform CAMP has produced the most objective list of threatened Anseriform taxa to date. The process of assigning Mace-Lande categories to Anseriformes initially identified 77 threat- ened taxa, including 59 not included in previous IUCN threatened lists, partly because subspecies have not been included in recent lists. While Endangered and Vulnerable were also used as labels in the IUCN categories Critical was a new label imparting a strong sense of urgency, with a
message that any taxa assessed as such is under immediate threat of extinction. Crit- ical Anseriform taxa include the Brazilian merganser Mergus octosetuceus (with a known population of around 20), Mada- gascar pochard Aythyu innotutu (only one individual seen in the last 20 years), Madagascar teal Anus bernieri (known population of fewer than 100 individuals), Campbell Island flightless teal Anus uuck- lundicu nesiotis (population of 3e100) and Crested shelduck Tudornu cristutu (last recorded in 1971).
Considerable attention has been focused on the problems of conserving migratory waterfowl. However, using the Bonn Con- vention definition of a migratory species as one for which a significant proportion of whose members cyclically and predictably cross one or more national jurisdictional boundaries, only 23% of threatened Anseriformes are migratory (Table 1). Furthermore. of the 29 taxa defined as Critical or Endangered only 7% are migra- tory and the only Critical taxon is the Crested shelduck. Migration is a general feature among wildfowl breeding in the large land masses at northern latitudes but the majority of threatened forms are resi- dent at tropical or sub1 ropical latitudes or on islands. There are currently no specific conservation plans for most of these non- migratory taxa. Hence, while there is a need to develop flyway plans for migratory species, there is also an urgent need to develop plans for resident species.
Species preservation calls for manage- ment strategieshecommendations which
CATEGORY MIGRATORY TAXA NON-MIGRATORY TOTAL TAXA
Critical 1 9 10 Endangered 1 18 19 Vulnerable 13 24 31
TOTAL 15 51 66
Table 1. Migratory and nonmigratory Anseriform taxa threatened with global extinction Listed by Mace-Lande categories (for details of categories see Ellis, this volume).
can minimize the risk of extinction. Once taxa were assigned categories of threat in the CAMP workshop, participants made recommendations for each taxon on the kinds of management action required for both wild and captive populations. For the Anseriformes, 173 of the 234 taxa (74%) were recommended for improved manage- ment programmes in the wild, such as better habitat protection. Recommenda- tions for taxonomic research were made for 94 taxa (40%), particularly to address the validity of questionable subspecies (such as the Tropical cinnamon teal Anus cyunopteru tropicu and Borreros cinna- mon teal A. cyunoptera borreroi, both clas- sified as Critical). Field surveys to clarify status and population size were recom- mended for 150 (64Y0) of Anseriform taxa and 92 taxa (39%) were recommended for Population and Habitat Viability Assess- ment workshops. The PHVAs, which com- bine computer simulation and analytical techniques to identify optimal manage- ment strategies for conserving animal pop- ulations, are always conducted in the range of the species, at the invitation of and in collaboration with responsible wildlife agencies. Among the avian species recently covered by PHVAs are the Whooping crane Grus americana, Hawaiian crow C o r t u ~ hmuiiensis, At twaters prairie chicken Tvmpunuchus cupid0 utticnteri, Waldrapp ibis Geronticus eremitu and the White-winged wood duck Cairinu scutulrtrl.
CAMPs also make recommendations regarding the need for husbandry research and the level of captive-breeding pro- gramme which is appropriate for each taxon.
The Global Captive Action Recom- mendation (see Ellis, this volume), which summarizes the captive status and man- agement priorities for taxa recommended by CAMPs on the world-wide basis, pro- poses that captive populations should be treated as an integral part of metapopula- tions being managed by conservation strategies and action plans.
The purpose of the GCAR is to provide strategic guidance for programmes at the global and regional level. In essence, this is a process that will help to ensure that efforts are not duplicated between regions and that the best collaborative use of captive space is facilitated. An important aspect of GCARs is the development of recommendations for target population sizes both on a global and a regional basis. Regional Taxon Advisory Groups and managers of Species Survival Plan-type programmes can then make decisions and take action concerning these collabor- atively developed recommendations.
There will be multiple genetic and demographic objectives depending on the status and outlook for a particular species in the wild. Some taxa will need large populations for a long time; others will need small populations which can be expanded later if needed.
Frequently the species most abundant in collections are those at least risk in the wild. The Anseriform CAMP recommen- ded managing