Australian Antarctic Division Details
|The following 14 out of 15 criteria
|Date Input||Yearly measurements|
Macquarie Island Details
Geographic Coverage is
Longitude (158.8 to 158.9)
Temporal range of the available data, as described by the metadata record, is from 15-Oct-1985.
Timespan: 1988 to 2012.
Number of data points: 42.
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Macquarie Island: Number of breeding females - Full census
Macquarie Island: Number of breeding females - Partial census
|Data Quality, Interpretation and
Analysis of Indicator Data
Two different methodologies have been employed to collect these data. From 1988 to 2004 a full census of all colonies on the island were conducted each year between the 13th and 17th of October - details of which are presented below. From 2005 onwards, owing to diminishing resources, a decision was made to only census a representative sample of the southern elephant seal colonies on the island. 5 colonies were selected as being representative of the whole island. Further information about this ''partial'' census can be found in a word document available for download from the URL given below.
In the data graphs displayed below, the ''Full Census'' graph present data collected between 1988 and 2004 using the full census method. The ''Partial Census'' graph present data from 1988 onwards using the partial census method - for the period 1988-2004, the figures for the 5 colonies used in the partial census have been obtained from the full census data.
Full Census Method:
Female Elephant seals haul-out to pup on island beaches according to a very regular pattern (Gaussian or Normal distribution) and timetable (peak haul-out between 13 and 17 October). They group together in ''harems'' with a few associated dominant males and are readily counted due to their obvious locations on open beaches and their lack of movement once ashore and having pupped. Thus counts of females can be made accurately to within +/- 5\\%.
The counts of the adult females (cows), fully weaned pups and dead pups are summed daily, and separately, through October for the west and east isthmus beaches. These totals represent the time distribution of numbers of cows ashore for each of these beaches. Corrections to the census totals are made in two stages:
Firstly, Gaussian curves are fitted to these distributions by least-squares calculations. From the equation to the curve for the west isthmus, the day of maximum numbers is determined as the calculated mean day. If the day of maximum numbers is not October 15, then the total for October 15 is increased by the proportional difference between it and the peak total of the fitted curve.
Secondly, the totals of the numbers for each of the five island zones counted on October 15 are increased to numbers predicted for the actual day of maximum cows ashore. This is done by transforming the fitted curve for the west isthmus into daily values of the proportion of cows present, from 1 (which is the number of cows at the peak of the curve) to fractions for each day on either side of the peak. Then the zone totals are divided by the fraction appropriate for their number of days delayed. This is done because the island beaches are grouped into five zones (see figure in instructions) which have characteristic day delays in their elephant seal cow numbers reaching a maximum with respect to the west isthmus area.
These delays are given in days:
ZONE- DAYS (delay from calc. peak day, west Isthmus)
North Head to Aurora Point - 0
Aurora Point to Caroline Cove - 3
Garden Cove to Sandy Bay - 2
Sandy Bay to Waterfall Bay - 3
Waterfall Bay to Hurd Point - 5
The total for the census is the sum of all these five adjusted zone totals.
|Data Usage Constraints|| '|
This data set conforms to the PICCCBY Attribution License
Please follow instructions listed in the citation reference provided at http://data.aad.gov.au/aadc/metadata/citation.cfm?entry_id=SOE_elephant_seals when using these data.
|Data Access Constraints|| '|
These data are publicly available for download from the URL given below.
A copy of the word document describing the census methodology adopted in 2005 is also available for download from the URL given below.
For definitions of the Scale categories, consult the Explanation of the Status Categories
The properties link can be used to view details of the parameters measured for this indicator.
Citation reference for this metadata record and dataset
Download page for Australian Antarctic Data Centre - SIMR Access 2000 Database
Download point for the word document detailing the methodology adopted in 2005
Download point for the complete census spreadsheets