Move, move, move, clear the way! I am in a rush to deliver my baby petrel. It's coming, I can feel my 'egg bump'. Epidural anesthesia, please. Clear the way to my burrow-nest.
The first ever incident documented in December 2012, as reported with “The Critically Endangered Mascarene Petrel Pseudobulweria aterrima” (Bull. B.O.C. 2014 134(3) & 2015 135(1)) – see below for plates 3 & 4.
Now, my friend Matthias Dehling recently realized that he also captured, and the second ever documentation of this miracle back in July 2018, this time of the Grey-faced Petrel Pterodroma gouldi – see plates 1 & 2.
Plate 1 & 2 show a gouldi female with a large egg in the uterus.
Supporting evidence indicates that what appears as an 'egg-bump' is indeed an egg: here Mattias courageously photographed a lady petrel on July 7, 2018, near the Poor Knights Islands in New Zealand. This date falls within the peak period of the species egg-laying, which typically occurs from the end of June to the beginning of the second week of July. The breeding population on the Three Kings Islands is believed to be quite large. In Mattias' images of the Grey-faced Petrel, similar to the Mascarene Petrel, a swollen area that we believe to be a large egg in the uterus is visible just above the cloaca.
Some interesting biological aspects: the Grey-faced Petrel is having one of the longest pre-laying exodus periods, spending 50-80 days at sea between courtship and egg-laying. During this time, the female must obtain the necessary nutrients to produce such a demanding egg before returning to her mate. Similar to human pregnancy, the male gains weight during the pre-laying exodus in preparation for sharing incubation duties while the female recovers. :-)
The Grey-faced Petrel is an icon in New Zealand petrel conservation, and we are grateful to the Department of Conservation for their efforts.
Plates 3 & 4 show the Critically Endangered aterrima with a large egg in the uterus (screenshots from Bulletin of the British Ornithologists' Club 2014 134(3) & 2015 135(1))
We will continue collecting similar documentation of flying female petrels and storm petrels with a visible ‘egg bump’ that symbolizes the continuation of species survival, and for further scientific publications. Please check your images carefully and stay in touch.
Hadoram,
of the Almodóvar Birding Center
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