{"id":112070,"date":"2021-12-14T13:18:36","date_gmt":"2021-12-14T17:18:36","guid":{"rendered":"https:\/\/birdfinding.info\/?p=112070"},"modified":"2022-01-13T10:16:31","modified_gmt":"2022-01-13T14:16:31","slug":"monteiros-storm-petrel","status":"publish","type":"post","link":"https:\/\/birdfinding.info\/monteiros-storm-petrel\/","title":{"rendered":"Monteiro\u2019s Storm-Petrel"},"content":{"rendered":"\t\t
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\u00a9 Peter Alfrey<\/a><\/p>\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t

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\n\t\t\t\nhttps:\/\/birdfinding.info\/wp-content\/uploads\/2021\/12\/XC657342-Monteiros-Storm-Petrel-Oceanodroma-monteiroi.mp3<\/a><\/audio>\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t
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\u00a9 Alba Villarroya<\/a><\/p>\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/div>\n\t\t\t\t

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Birdfinding.info \u21d2<\/em><\/strong>\u00a0 Recently described and little-known, Monteiro\u2019s Storm-Petrel<\/strong> is locally common in the central Azores from late March into October.\u00a0 Most sightings are in the waters east of Graciosa, especially at Fortuna Bank.\u00a0 The largest known colony is on Ilh\u00e9u de Praia, which lies about 1 km offshore from the port town of Praia\u2014however, the adults attend the colony nocturnally and are rarely seen from the town during daylight hours.<\/p>\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/section>\n\t\t\t\t

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Monteiro\u2019s Storm-Petrel<\/strong><\/p>\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t

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Hydrobates monteiroi<\/em><\/p>\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/div>\n\t\t\t\t

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Family: Hydrobatidae<\/a><\/strong><\/p>\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/section>\n\t\t\t\t

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Endemic to the Azores; range at sea unknown.<\/strong><\/p>\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/section>\n\t\t\t\t

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Conjectural at-sea distribution of Monteiro\u2019s Storm-Petrel. \u00a0\u00a9 BirdLife International 2018<\/a><\/p>\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/div>\n\t\t\t\t

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Breeds mainly on islets adjacent to three or four of the main Azorean islands.\u00a0 The majority (~300 pairs) nest near Graciosa on Baixo, Baleia, and Praia islets.\u00a0 Smaller numbers nest on islets near Flores, and are suspected of breeding around Corvo, and possibly also around S\u00e3o Miguel (detected nearshore in summer).<\/p>

The breeding season is approximately March to October.\u00a0 Adults return in March and lay their eggs in May or June, with a few in early July.\u00a0 Juveniles fledge in late August and September, with a few in early October.<\/p>

There appear to be no confirmed records outside of the Azorean archipelago.\u00a0 Tissue sample evidence of its winter diet reportedly suggests that it remains in the central North Atlantic, and is essentially non-migratory\u2014 unlike \u201cGrant\u2019s Storm-Petrel\u201d<\/strong><\/a>, for which the comparable evidence corroborates its known migratory pattern.\u00a0 (These tissue samples were collected for the original research project that initially detected differences between the populations and ultimately led to the recognition of Monteiro\u2019s as a separate species.)<\/p>\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/section>\n\t\t\t\t

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Identification<\/strong><\/span><\/p>

As a cryptic species within the Band-rumped Storm-Petrel<\/strong><\/a> complex, Monteiro\u2019s is visually indistinguishable from other band-rumped-type storm-petrels under most circumstances.<\/p>

Its tail averages much more deeply notched than on \u201cGrant\u2019s\u201d<\/strong><\/a>\u2014the other band-rumped-type storm-petrel that breeds in the Azores\u2014but can still appear square at some angles or when fanned.\u00a0 In the hand, Monteiro\u2019s averages slightly smaller than \u201cGrant\u2019s\u201d in most measurements, but with a slightly longer tail and proportionately longer wings.\u00a0 (Except for tail-notch depth, all of these metrics overlap widely.)<\/p>\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/section>\n\t\t\t\t

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Monteiro\u2019s Storm-Petrel, showing characteristically notched tail and molting secondaries\u2014which is normal for an adult late in its breeding season.\u00a0 (Banco da Fortuna, offshore east of Graciosa, A\u00e7ores, Portugal; August 25, 2013.)\u00a0 \u00a9 Richard Bonser<\/a><\/p>\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t

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Like other band-rumped-type storm-petrels, Monteiro\u2019s is dark-brown overall, with an even white band across the rump that usually extends partway down the sides of the rump to the undertail.<\/p>\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/div>\n\t\t\t\t

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Band-rumped-type storm-petrels strongly resemble storm-petrels of other groups (such as Leach\u2019s<\/strong><\/a> and Wilson\u2019s<\/strong><\/a>), and are best distinguished by their characteristic flight pattern: which is comparatively steady and stable, often gliding on flat wings like a shearwater.<\/p>\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t

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Monteiro\u2019s Storm-Petrel\u2014identification presumed based on location and season, despite lack of visible tail notch in this view.\u00a0 (Offshore southeast of Graciosa, A\u00e7ores, Portugal; May 26, 2007.)\u00a0 \u00a9 Killian Mullarney<\/a><\/p>\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/section>\n\t\t\t\t

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As with most dark storm-petrels, all band-rumped-types typically show a paler brown or whitish diagonal stripe on the wing coverts, but the boldness varies depending on molt-stage and lighting.\u00a0 So the apparent color and boldness of the wingbar can provide clues to the age and molt-stage of closely observed individuals.<\/p>

Juveniles and freshly molted adults have the most pronounced wingbars.\u00a0 On juveniles the bar appears white.\u00a0 On adults returning to the breeding grounds, the bar is blond.\u00a0 With feather-wear, the bar diminishes and can disappear entirely by the time the next molt begins.<\/p>

For conditions where wing-molt can be discerned: adult Monteiro\u2019s begins molting in late summer and completes in mid-winter; and first-year Monteiro\u2019s would likely begin molting in May and complete in September (see Howell & Zufelt 2021).\u00a0 Note that this expected seasonality of feather-wear and replacement is effectively identical to that of \u201cMadeiran Storm-Petrel\u201d<\/strong><\/a>.<\/p>\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/section>\n\t\t\t\t

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Monteiro\u2019s Storm-Petrel\u2014identification presumed based on location and season.\u00a0 (Offshore from Graciosa, A\u00e7ores, Portugal; June 2, 2011.)\u00a0 \u00a9 Richard Bonser<\/a><\/p>\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/div>\n\t\t\t\t

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Monteiro\u2019s Storm-Petrel, apparently molting secondaries late in the breeding season\u2014as is expected for adult Monteiro\u2019s in late summer.\u00a0 (Offshore from Graciosa, A\u00e7ores, Portugal; September 1, 2019.)\u00a0 \u00a9 Fran\u00e7ois Stocman<\/a><\/p>\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/section>\n\t\t\t\t

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Voice.<\/em><\/strong>\u00a0 Two types of calls are heard at breeding colonies: chattering and purring.\u00a0 Both resemble the equivalent calls of other storm-petrels, but differ in their patterns.<\/p>

Monteiro\u2019s\u2019 chatter call is shorter and simpler than the calls of other North Atlantic band-rumped-types: typically comprising four to six notes, whereas the others vary from six up to sixteen (4 to 6 in Monteiro\u2019s; 9 in \u201cGrant\u2019s\u201d; 6 to 11 in \u201cMadeiran\u201d; 11 to 16 in Cape Verde).<\/p>

Monteiro\u2019s\u2019 purring call consists of a rough purr or rattle followed by one or more \u201cyelps\u201d (less squeaky than other band-rumped-types, more like the scratch of a phonograph needle) with a brief gap between the purr and the yelp: