Conservation status

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The conservation status of particular ant species is an important factor in their study. Red Listed ants that are Critically Endangered or Endangered must not be captured, killed or disturbed in any manner. They are threatened with extinction. Similar care should be taken with Vulnerable ant species as well.

IUCN Red List 1994 (v2.3) categories

INTRODUCTION

Ants are an important taxon for inclusion in conservation policies and conservation strategies. One approach is to identify those ants threatened with extinction. The IUCN Red List of Threatened Species is the best-known worldwide conservation status listing and ranking system. The system divides threatened species into three categories: Critically Endangered (CR), Endangered (EN), and Vulnerable (VU).

Out of the 14,578 valid extant species and subspecies, there are 141 ant species (~1%) on this Red List.

A list of ant species currently on the IUCN Red List.

Please see the Wikipedia article Conservation Status for more about the IUCN Red List.

Criteria for Placement on the Red List

III. DEFINITIONS 1. Population and Population Size (Criteria A, C and D) The term ‘population’ is used in a specific sense in the Red List Criteria that is different to its common biological usage. Population is here defined as the total number of individuals of the taxon. For functional reasons, primarily owing to differences between life forms, population size is measured as numbers of mature individuals only. In the case of taxa obligately dependent on other taxa for all or part of their life cycles, biologically appropriate values for the host taxon should be used. 2. Subpopulations (Criteria B and C) Subpopulations are defined as geographically or otherwise distinct groups in the population between which there is little demographic or genetic exchange (typically one successful migrant individual or gamete per year or less). 3. Mature individuals (Criteria A, B, C and D) The number of mature individuals is the number of individuals known, estimated or inferred to be capable of reproduction. When estimating this quantity, the following points should be borne in mind: • Mature individuals that will never produce new recruits should not be counted (e.g. densities are too low for fertilization). • In the case of populations with biased adult or breeding sex ratios, it is appropriate to use lower estimates for the number of mature individuals, which take this into account. • Where the population size fluctuates, use a lower estimate. In most cases this will be much less than the mean. • Reproducing units within a clone should be counted as individuals, except where such units are unable to survive alone (e.g. corals). • In the case of taxa that naturally lose all or a subset of mature individuals at some point in their life cycle, the estimate should be made at the appropriate time, when mature individuals are available for breeding. • Re-introduced individuals must have produced viable offspring before they are counted as mature individuals. 4. Generation (Criteria A, C and E) Generation length is the average age of parents of the current cohort (i.e. newborn individuals in the population). Generation length therefore reflects the turnover rate of breeding individuals in a population. Generation length is greater than the11 age at first breeding and less than the age of the oldest breeding individual, except in taxa that breed only once. Where generation length varies under threat, the more natural, i.e. pre-disturbance, generation length should be used. 5. Reduction (Criterion A) A reduction is a decline in the number of mature individuals of at least the amount (%) stated under the criterion over the time period (years) specified, although the decline need not be continuing. A reduction should not be interpreted as part of a fluctuation unless there is good evidence for this. The downward phase of a fluctuation will not normally count as a reduction. 6. Continuing decline (Criteria B and C) A continuing decline is a recent, current or projected future decline (which may be smooth, irregular or sporadic) which is liable to continue unless remedial measures are taken. Fluctuations will not normally count as continuing declines, but an observed decline should not be considered as a fluctuation unless there is evidence for this. 7. Extreme fluctuations (Criteria B and C) Extreme fluctuations can be said to occur in a number of taxa when population size or distribution area varies widely, rapidly and frequently, typically with a variation greater than one order of magnitude (i.e. a tenfold increase or decrease). 8. Severely fragmented (Criterion B) The phrase ‘severely fragmented’ refers to the situation in which increased extinction risk to the taxon results from the fact that most of its individuals are found in small and relatively isolated subpopulations (in certain circumstances this may be inferred from habitat information). These small subpopulations may go extinct, with a reduced probability of recolonization. 9. Extent of occurrence (Criteria A and B) Extent of occurrence is defined as the area contained within the shortest continuous imaginary boundary which can be drawn to encompass all the known, inferred or projected sites of present occurrence of a taxon, excluding cases of vagrancy (see Figure 2). This measure may exclude discontinuities or disjunctions within the overall distributions of taxa (e.g. large areas of obviously unsuitable habitat) (but see ‘area of occupancy’, point 10 below). Extent of occurrence can often be measured by a minimum convex polygon (the smallest polygon in which no internal angle exceeds 180 degrees and which contains all the sites of occurrence). 10. Area of occupancy (Criteria A, B and D) Area of occupancy is defined as the area within its ‘extent of occurrence’ (see point 9 above) which is occupied by a taxon, excluding cases of vagrancy. The measure reflects the fact that a taxon will not usually occur throughout the area of its extent of occurrence, which may contain unsuitable or unoccupied habitats. In some cases (e.g. irreplaceable colonial nesting sites, crucial feeding sites for migratory taxa) the area of occupancy is the smallest area essential at any stage to the survival of existing populations of a taxon. The size of the area of occupancy will be a function of the scale at which it is measured, and should be at a scale appropriate to relevant biological aspects of the taxon, the nature of13 threats and the available data (see point 7 in the Preamble). To avoid inconsistencies and bias in assessments caused by estimating area of occupancy at different scales, it may be necessary to standardize estimates by applying a scale-correction factor. It is difficult to give strict guidance on how standardization should be done because different types of taxa have different scale-area relationships. 11. Location (Criteria B and D) The term ‘location’ defines a geographically or ecologically distinct area in which a single threatening event can rapidly affect all individuals of the taxon present. The size of the location depends on the area covered by the threatening event and may include part of one or many subpopulations. Where a taxon is affected by more than one threatening event, location should be defined by considering the most serious plausible threat. 12. Quantitative analysis (Criterion E) A quantitative analysis is defined here as any form of analysis which estimates the extinction probability of a taxon based on known life history, habitat requirements, threats and any specified management options. Population viability analysis (PVA) is one such technique. Quantitative analyses should make full use of all relevant available data. In a situation in which there is limited information, such data as are available can be used to provide an estimate of extinction risk (for instance, estimating the impact of stochastic events on habitat). In presenting the results of quantitative analyses, the assumptions (which must be appropriate and defensible), the data used and the uncertainty in the data or quantitative model must be documented.

Social Parasites

Social parasites are dependent upon host population density and other factors. Social parasites typically have a "patchy" distribution pattern and are extremely rare. We are still discovering new species of social parasites and trying to understand the factors driving their evolution.

Rare species in specialized habitats

Obligatory predators on termites, subterranean ants, ants in remote mountain tops, etc. Once the host or prey becomes reduced, the entire population is at risk of extinction.

Rare species in endangered habitats

Ants that have had most of their habitat degraded or removed via logging, agriculture, city development or other factors. Many of these ant species are on islands and have a limited distribution.

Case Histories

  • Ants of Romblon Islands in the Philippine Archipelago. Romblon province consists of three islands sitting in the Sibuyan Sea. Romblon's three major islands are: 1.) Romblon Island, 2.) Tablas Island, and 3.) Sibuyan Island. Sibuyan Island is known to have been isolated and rather stable in its present location for millions of years. It has an area of 445 km². The island has two prominent peaks, Mount Guiting-Guiting with a height of 2,058 m and Mount Nailog with a height of 789 m. Recent mammal research by the Chicago Field Museum (Steve Goodman) has discovered several endemic rodents and an endemic bat. The ants of this island are virtually unknown at present but species found there and no-where else on the Philippine islands should be considered threatened and efforts should be made to protect their habitat from destruction.
  • Fiji Islands
  • Vanuatu
  • Solomon Islands
  • Bismark Archipelago

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