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Annual population estimates of Southern Elephant Seals at Macquarie Island from censuses made annually on October 15th.

Entry ID: SOE_elephant_seals

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Summary

Abstract: INDICATOR DEFINITION
Count of all adult females, fully weaned pups and dead pups hauled out on, or close to, the day of maximum cow numbers, set for October 15.

TYPE OF INDICATOR
There are three types of indicators used in this report:
1.Describes the CONDITION of important elements of a system;
2.Show the extent of the major PRESSURES exerted on a system;
3.Determine RESPONSES to either ...

Related URL

Link: GET DATA

Description: Display Antarctic State of Environment Indicator 31 - Access data and report

Geographic Coverage

(Click for Interactive Map)

Spatial coordinates

N: -54.6

S: -54.7

E: 158.9

W: 158.8

Temporal Coverage

Start Date: 1985-10-15

Location Keywords

OCEAN > SOUTHERN OCEAN

OCEAN > SOUTHERN OCEAN > MACQUARIE ISLAND

GEOGRAPHIC REGION > POLAR

Science Keywords

BIOLOGICAL CLASSIFICATION > ANIMALS/VERTEBRATES > MAMMALS > CARNIVORES > SEALS/SEA LIONS/WALRUSES
BIOSPHERE > ECOLOGICAL DYNAMICS > SPECIES/POPULATION INTERACTIONS > POPULATION DYNAMICS

ISO Topic Category

BIOTA

OCEANS

Platform

FIELD SURVEYS

Quality 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.

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.

Use Constraints This data set conforms to the PICCCBY Attribution License
(http://creativecommons.org/licenses/by/3.0/).

Please follow instructions listed in the citation reference provided at http://data.aad.gov.au/aadc/metadata/citation.cfm?entry_id=SOE_elep... when using these data.

Ancillary Keywords

MACQUARIE ISLAND

MIROUNGA LEONINA

Data Set Progress

IN WORK

Data Center

Australian Antarctic Data Centre, Australia

Data Center URL: http://data.aad.gov.au

Data Center Personnel
Name: DATA OFFICER AADC Phone: +61 3 6232 3244 Fax: +61 3 6232 3351 Email: metadata at aad.gov.au Contact Address: Australian Antarctic Division 203 Channel Highway City: Kingston Province or State: Tasmania Postal Code: 7050 Country: Australia

Distribution

Distribution Media: HTTP

Distribution Format: html, excel

Fees: free

Distribution Media: HTTP

Distribution Size: 1,463 kb

Distribution Format: word

Fees: free

Personnel

ROSEMARY GALES

Role: INVESTIGATOR

Role: TECHNICAL CONTACT

Phone: +61 3 6233 3865

Fax: +61 3 6233 3477

Email: rgales at dpiw.tas.gov.au

Contact Address:

Wildlife and Marine Conservation Section

Department of Primary Industry and Water

GPO BOX 44

City: Hobart

Province or State: Tasmania

Postal Code: 7001

Country: Australia

HARRY BURTON

Role: INVESTIGATOR

Email: harry.burton at aad.gov.au

Contact Address:

Australian Antarctic Division

203 Channel Highway

City: Kingston

Province or State: Tasmania

Postal Code: 7050

Country: Australia

COLIN JOHN DAVIS

Role: DIF AUTHOR

Contact Address:

Australian Antarctic Division

203 Channel Highway

City: Kingston

Province or State: Tasmania

Postal Code: 7050

Country: Australia

Publications/References

Hindell, M.A., Burton, H.R. (1987), Past and Present Status of the Southern Elephant Seal (Mirounga leonina) at Macquarie Island., Journal of Zoology, 213, 365-380

Creation and Review Dates

DIF Creation Date: 2001-08-08

Last DIF Revision Date: 2011-05-31

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