Breeding populations of Southern Giant Petrels at Heard Island, the McDonald Islands and within the AAT

Brief description

This indicator is no longer maintained, and is considered OBSOLETE.

INDICATOR DEFINITION
The number of breeding pairs of Southern Giant Petrels at Heard Island, the McDonald Islands, and in colonies near Casey, Davis and Mawson stations.

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 condition or changes in the condition of a system.

This indicator is one of: CONDITION

RATIONALE FOR INDICATOR SELECTION
The breeding population of Southern Giant Petrels is related to resource availability (nesting space and food), behavioural mechanisms (immigration/emigration and breeding effort/success) in addition to climate change and human impacts (including fisheries and human disturbance). Monitoring breeding populations and interpretation of the data provides information on changes in the Antarctic and Subantarctic ecosystems.

DESIGN AND STRATEGY FOR INDICATOR MONITORING PROGRAM
Spatial scale: Colonies near Australian Stations -
Frazier Islands, Casey (lat 66 degrees 16' 54.5' S, long 110 degrees 31' 39.4' E)
Hawker Island, Davis (lat 68 degrees 34' 35.8' S, long 77 degrees 58' 02.6' E)
Giganteus Island, Mawson (lat 67 degrees 36' 09.7' S, long 62 degrees 52' 25.7' E)

Heard Island - (lat 53 degrees 06' 00.0' S, long 73 degrees 31' 59.9' E)

McDonald Islands - (lat 53 degrees 02' 26.2' S, long 72 degrees 36' 00.0' E)

Frequency: Breeding Southern Giant Petrels are easily disturbed. Colonies are visited every 3-5 years to minimise disturbance to breeding birds.

Measurement technique: All colonies are visited and breeding birds are counted from outside the colonies by two personnel performing replicate counts. All breeding individuals in a colony are counted. No birds are disturbed off their nests.

Considerations regarding disturbance associated with census visits are also incorporated into monitoring strategies. The lack of annual census data does not reduce the value of these long-term monitoring programmes.

RESEARCH ISSUES
All Southern Giant Petrel breeding populations in the AAT and at HIMI decreased following their discovery. Southern Giant Petrels breeding on Indian Ocean islands are highly sensitive to human disturbance. Access to breeding colonies is restricted, as are the types of activities permitted. Disturbance from researchers has been implicated in the observed decreases in these populations (Woehler et al. 2001, Woehler et al. in press). Analyses of the long term AAT data suggest that the breeding populations at Hawker Is and at the Frazier Is have recovered following the restrictions on access and activities permitted on breeding islands.

LINKS TO OTHER INDICATORS

Lineage

Progress Code: completed

Statement: This indicator is now OBSOLETE. These data are no longer archived in this location, and are therefore not up-to-date.

Censuses of breeding adults are performed and long term trends are determined. Integration with other long term datasets is currently underway through international collaborations, allowing comparison among sites at regional and ecosystem scales. Some analyses and their interpretations have been published (see bibliography), and current analyses will examine population data as they are compiled.