What you are seeing is not what you might expect. It is actually a large-billed adult male Zino's Petrel, which further validates the measurements we have taken. These measurements include bill length, bill depth from the last feather above the nostril tube, bill depth immediately in front of the nostril tube, and bill depth at the maxillary nail/hook to gonys.
You can download the biometrics from the Birding World paper from 2010 here.
This confirms that large-billed Zino's Petrels can have dimensions and bulbous development that overlap with the smaller-billed Desertas Petrels, which are mostly females and/or juveniles.
I captured this photograph of the gadfly on March 4, 2024, in the waters off Madeira Island, Portugal.
Date return of the Zino’s
As far as I know, this is the earliest seasonal return date ever recorded for Zino’s Petrel in Madeira’s waters, and for any Pterodroma species in the ocean. The date of the 4th of March is also close to the earliest Zino’s Petrel recorded over the years (by Frank Zino and Madeira Wind-birds) upon return to the colony on the main Madeira Island. According to Frank’s data, the earliest recorded Zino’s Petrels at the colony were back in the 80s, when Frank had one bird fly over on the 28th of February! Frank happened to remember this date because it was his wife Buffy’s birthday. They were in the freezing cold at Areeiro. On a personal note, it is not surprising to know that the Zino family celebrates their birthdays, and maybe even honeymoons, with their petrel, the Zino’s Petrel they saved over the years. Frank just reminded me it was the exact spot, when some years later I suggested that we must try to trap a Zino’s Petrel together, and we did! So here is the official seasonal return date of the Zino’s Petrel: 28th February to 4th March!
The early date is a strong bias in the identification process for eliminating Desertas Petrels, which mostly return to the Madeira Islands from mid-April, and still vastly during May.
Zino’s versus Desertas Petrels
Since this bird is a large-billed Zino’s petrel, but also a dark-winged Zino’s petrel, some key identification clues should be considered - both in combination and analogously - in the process, as it could easily be overlooked as a Desertas or even Cape Verde Petrel.
In the forthcoming Gadfly Petrels volume (The Tubenoses Project, Almodóvar; Bloomsbury, London), with my coauthor Vincent Bretagnolle, we are introducing a completely new identification model for the separations of the three members of the feae complex, which could even assist in the separation of such challenging dark-winged and large-billed Zino’s from the Desertas, and even the latter versus the Cape Verde Petrels.
Putting this interesting but challenging dark-winged and large-billed Zino’s from the 4th of March 2024, into the new modeling, it resulted as ‘Difficult Zino’s’, falling within the scale of a Zino’s with mostly dark underwing (score 0 & 1, equivalent to wing Types 0-2), and hence mostly inseparable from Cape Verde and Desertas Petrels on underwing pattern; and therefore the identification becomes primarily based on correct evaluation of overall lighter build, and still key differences in bill dimensions and structure in clues-up images. (Because of the nature of these structural elements, analyzing and confirming with a set of good images during prolonged views is vital.)
This bird has been delimited into Zino’s in all 10+ parameters that can be broadly divided into three main categories, of Conclusive, Supportive & Inconclusive (latter two are tendencies of various levels). I will give you two examples here: the extensive brown smudging on the flanks, and the development of bold white basal and outer webs of GPC – are a key combination – encompassing many of the coverts, and yet not forming the Desertas’ diagnostic crescentic mark! The rest will be found in the Gadfly Petrels volume (of the Tubenoses Monograph).
Zino’s threat alert
In relation to the above dating for the Zino’s Petrel to the Madeira's waters, which were indeed the earliest Zino’s seen on its return to the 2024 season on Madeira! And as I am writing these lines, Frank Zino just informed me of a massive fire around the Zino’s colonies now threatening many of the young Pterodroma chicks and obviously their parents too, as these are habitually not willing to leave the chick, or even attracted to the fire’s lighting to be burned alive.
I will conclude with two videos: one showing the sky filled with Zino's Petrels socializing above the colony at night (taken in May 2024), and the other showing the burning mountains of Madeira from last night (23-24 August). Let's hope the damage to the Zino's breeding population, breeding season, and nests will not be too catastrophic for the future of the species.
From the Almodóvar Birding Center, we will continue to provide updates on the development of all tubenoses in the related islands of Madeira and Azores (Portugal), Canaries (Spain), and the Cape Verde Islands.
Photo credit: Hadoram Shirihai; video credits: Frank Zino, Philip R Boak/Royal Naval Birdwatching Society
Hadoram Shirihai, The Tubenoses Project, Almodóvar Birding, Portugal
(in collaboration with Frank Zino, Vincent Bretagnolle, Miguel Demeulemeester, and the Freira Conservation Project - FCP, Madeira, Portugal; & Madeira Wind-birds, Madeira, Portugal)
24 Aug 2024
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