| Estimates from Surveys | Guesses | % Known and Possible Range | Area (km2) | |||
|---|---|---|---|---|---|---|
| Survey category | Estimate | ± 95% CL | From | To | ||
| Aerial Sample Counts | 68 | 113 | — | — | 69.2 | 17,034 |
| Reliable Dung Counts | 631 | 218 | — | — | 14.6 | 3,606 |
| Informed Guesses | 3 | — | 199 | 326 | 4.8 | 1,172 |
| Degraded Data | — | — | 500 | 500 | 0.0 | 0 |
| Totals 2015 | 702 | 245 | 699 | 826 | ||
| Totals 2006 | 929 | 820 | 1,585 | 2,085 | ||
| Assessed Range | 88.6 | 21,812 | ||||
| Unassessed Range | 11.4 | 2,807 | ||||
| Total Range | 100 | 24,619 | ||||
| Data Category | Definite | Probable | Possible | Speculative |
|---|---|---|---|---|
| Direct Sample Counts and Reliable Dung Counts | 454 | 245 | 245 | 0 |
| Informed Guesses | 3 | 0 | 199 | 127 |
| Other Guesses | 0 | 0 | 0 | 500 |
| Totals 2015 | 457 | 245 | 444 | 627 |
| Totals 2006 | 109 | 1,689 | 1,036 | 500 |
| Estimates from Surveys | Guesses | Area | ||||
|---|---|---|---|---|---|---|
| Cause of Change | Estimate | ± 95% CL | From | To | % Known and Possible | Total |
| New Population | +3 | 0 | +47 | +147 | 1.7 | 416 |
| Different Technique | +631 | ±218 | -869 | -869 | 14.6 | 3,606 |
| Different Area | -861 | ±828 | 0 | 0 | 69.2 | 17,034 |
| New Guess | 0 | 0 | +152 | +179 | 3.1 | 756 |
| Data Degraded | 0 | 0 | 0 | -500 | 0.0 | 0 |
| Totals | -227 | ±856 | -670 | -1,043 | 88.6 | 21,812 |
| Cause of Change | Definite | Probable | Possible | Speculative |
|---|---|---|---|---|
| New Population | +3 | 0 | +47 | +100 |
| Different Technique | +443 | -681 | +199 | 0 |
| Different Area | -14 | -847 | -840 | 0 |
| New Guess | 0 | 0 | +152 | +27 |
| Totals | +432 | -1,528 | -443 | +127 |
| Data Category | Known Range | Possible Range | Total Range |
|---|---|---|---|
| Direct Sample Counts and Reliable Dung Counts | 20,640 | 0 | 20,640 |
| Informed Guesses | 1,172 | 0 | 1,172 |
| Unassessed Range | 872 | 1,935 | 2,807 |
| Totals | 22,684 | 1,935 | 24,619 |
| Cause of | Survey Details2 | Number of Elephants | Area | Map Location | |||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| Input Zone | Change1 | Type | Reliab. | Year | Estimate | 95% C.L. | Source | PFS3 | (km²) | Lon. | Lat. |
| + Bangassou Forest Reserve | - | O | E | 2004 | 500 | 500* | Blake, 2005 | 1 | 12,011 | 23.3E | 5.2N |
| + Chinko Drainage Basin | NP | O | D | 2015 | 50 | 100* | Aebischer, pers. comm., 2016 | 1 | 19,000 | 23.9E | 6.5N |
| + Dzangha Ndoki National Park and Special Reserve | DT | DC | B | 2012 | 631 | 218 | Princée, 2013 | 1 | 3,861 | 16.2E | 2.8N |
| + Northern Landscape | DA | AS | B | 2010 | 68 | 113 | Bouché, 2011 | 1 | 94,962 | 20.8E | 8.2N |
| + Yobe-Lidjombe | NG | O | D | 2012 | 152 | 27* | Princée, 2013 | 2 | 756 | 16.3E | 2.7N |
* Range of informed guess
1Key to Causes of Change (only tracked since 2007): DA: Different Area; DD: Data Degraded; DT: Different Technique; NA: New Analysis; NG: New Guess; NP: New population; PL: Population Lost; RS: Repeat Survey (RS ́ denotes a repeat survey that is not statistically comparable for reasons such as different season); –––: No Change
2Key to Survey Types: AC: Aerial Count, not specified; AS: Aerial Sample Count; AT: Aerial Total Count; DC: Dung Count; EX: Extrapolation from GIS; GD: Genetic Dung Count; GS: Ground Sample Count; GT: Ground Total Count; IG: Informed Guess; IR: Individual Registration; OG: Other Guess. Survey Type is followed by an indicator of survey quality, ranked from 1 to 3 (best to worst). Survey Reliability is keyed A-E (best to worst) as outlined in this table.
3PFS: Priority for Future Surveys, ranked from 1 to 5 (highest to lowest). Based on the precision of estimates and the proportion of national range accounted for by the site in question, PFS is a measure of the importance and urgency for future population surveys. All areas of unassessed range have a priority of 1. See Introduction for details on how the PFS is derived.
Note that totals for the Definite, Probable, and Possible categories are derived by pooling the variances of individual estimates, as described at http://www.africanelephantdatabase.org/reliability. As a result, totals do not necessarily match the simple sum of the entries within a given category.
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