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, 8 (1), 3926

Multi-modal Survey of Adélie Penguin Mega-Colonies Reveals the Danger Islands as a Seabird Hotspot


Multi-modal Survey of Adélie Penguin Mega-Colonies Reveals the Danger Islands as a Seabird Hotspot

Alex Borowicz et al. Sci Rep.


Despite concerted international effort to track and interpret shifts in the abundance and distribution of Adélie penguins, large populations continue to be identified. Here we report on a major hotspot of Adélie penguin abundance identified in the Danger Islands off the northern tip of the Antarctic Peninsula (AP). We present the first complete census of Pygoscelis spp. penguins in the Danger Islands, estimated from a multi-modal survey consisting of direct ground counts and computer-automated counts of unmanned aerial vehicle (UAV) imagery. Our survey reveals that the Danger Islands host 751,527 pairs of Adélie penguins, more than the rest of AP region combined, and include the third and fourth largest Adélie penguin colonies in the world. Our results validate the use of Landsat medium-resolution satellite imagery for the detection of new or unknown penguin colonies and highlight the utility of combining satellite imagery with ground and UAV surveys. The Danger Islands appear to have avoided recent declines documented on the Western AP and, because they are large and likely to remain an important hotspot for avian abundance under projected climate change, deserve special consideration in the negotiation and design of Marine Protected Areas in the region.

Conflict of interest statement

The authors declare no competing interests.


Figure 1
Figure 1
(a) Map showing the location of the Antarctic Peninsula and (b), the location of the Danger Islands group on the Antarctic Peninsula, both created using ESRI ArcMap 10.0 ( (c) Quickbird image of the Danger Islands taken 22 January 2011 (©2018, DigitalGlobe).
Figure 2
Figure 2
Guano areas (yellow) identified on Brash Island (at left) and Heroína Island (at right) from 1957 to present day. (a) and (h) manually classified from aerial imagery from 1957; (b) and (i) manually classified from aerial imagery from 1957 and reduced to 30 m cells for comparison with Landsat; (c) and (j): Landsat-4 in 1990 classified as described in Methods; (d) and (k) Landsat-7 in 2000 classified as described in the Methods; (e) and (l) Landsat-8 in 2015 classified as described in the Methods; (f) Worldview-2 image taken 19 February 2016 classified as described in the Methods (©2018, DigitalGlobe); (m) Worldview-2 image taken 2 December 2015 classified as described in the Methods (©2018, DigitalGlobe); (g) and (n) nests that were retained by the spatial filter marked as yellow dots overlaid on UAV imagery from ground survey described in this manuscript. Panels a, b, f, g, h, i, m, and n displayed using ESRI ArcMap 10.0 (; Panels c, d, e, h, k, and l displayed using ENVI 5.4 (
Figure 3
Figure 3
UAV orthomosaic image of Brash Island (above), with examples of zoomed-in penguin rookeries (below), displayed using ESRI ArcMap 10.0 (

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