Hydrurga Rocks (HYDR)

64˚08’S, 61˚37’W

Magnetic declination: 14.5˚E

Inventory subarea: NW

Inventory acronym: HYDR

Species Diversity: LOW

Site Sensitivity: LOW                                                  Note: Restricted visitor space

 

Location — History — Features

A group of rocks lying E of Two Hummock Island in the Palmer Archipelago, and named after the leopard seal, Hydrurga leptonyx . These low, rocky islands rise to approximately 25 meters above sea level and have a bare-rock summit. Snow cover may totally cover the area in November. The narrow shingle beach is made up largely of pebbles and cobbles of angular to subrounded blocks, with some minor sand and granules. Several of the smaller rocks surrounding the main island are connected by causeways of this shingle material. Glacially polished rock surfaces are extensive.

Landing Characteristics

Rock-strewn island, which approaching zodiacs must negotiate carefully to avoid shallow rocks. Visitors must climb uphill from the regular landing rocks, sometimes through deep early-season snow, to reach numerous, discrete groups of chinstrap penguins. An additional set of chinstrap colonies to the N are more difficult to access. Shag nests are relatively inaccessible in heavy snow cover, but may be more accessible in mid- to late-summer. There appear to be few vantage points for photo-documentation.

Antarctic Site Inventory Effort

Visits by Antarctic Site Inventory researchers, 1994-2003:

1.    November 18, 1995    BH        W. Discoverer

2.    December 1, 1995    BH SF        W. Discoverer

3.    November 25, 1996    SF WT RN    Explorer

4.    December 17, 1999    RN        Cal Star

5.    December 26, 2000    SF LF        Cal Star

6.    December 23, 2001    JC LGC        Endeavour

7.    January 3, 2002        RP        Endeavour

8.     January 1, 2003        RP        Endeavour

9.     January 11, 2003        SF        Endeavour

Assessment and monitoring. Preliminary surveying, mapping, and photodocumentation (terrestrial). Regular censusing of chinstrap penguin groups (##1-20) and blue-eyed shags. More thorough ground survey of floral communities, after snow cover recedes, is needed.

Fauna — Flora — Censuses

Penguins & flying birds . Chinstrap penguins, blue-eyed shags, and kelp gulls are confirmed breeders. Antarctic brown skuas noted, and also may breed.

Antarctic Site Inventory censuses:

Chinstrap penguin (site-wide)

526    N1    1996 Nov

420    N1    2000 Dec

398    N1    2003 Jan

Blue-eyed shag (site-wide)

 21    N1    1996 Nov

 13    N1    2000 Dec

 12    N1    2003 Jan

Recent chinstrap penguin census data reported in Woehler (1993): 1,000 N4/5, 1986.

Seals . Leopard seals observed patrolling the site. Weddell seals hauled-out on cobble shoreline and on snow-covered areas above the shoreline.

Flora . Virtually total snow cover during Inventory visits.

Conservation Aspects

Site sensitivities. Restricted visitor space and upward climb (often, through snow) to reach the penguins, whose nests are readily approached. Steep cliff edges.

Pointers for avoiding disruptions.

• Walk slowly and carefully around nesting, crèching, or molting chinstrap penguins.
• Do not impede penguins’ access to and from the water.
• If extensive snow cover, avoid — and do not walk in or block — trails that penguins have made through the snow.
• Stay clear of — and do not hike upon or wander over — cliff edges.

Visitation Aspects

Numbers of tourist zodiac landings and participating visitors, 1989-2003:    

 

 

Proximate visitor sites . Sprightly Islands lie to the SE; Portal Point (Charlotte Bay) to the S; Mikklesen Harbor and Astrolabe Island to the NE.