Hybrid and aberrant Anseriformes in Spain, winter 2001-2002

Photos by Ferran López, Delfín González and Ricard Gutiérrez
All comments by Ricard Gutiérrez

The presumed hybrid Mallard x Red-crested Pochard
The melanistic mallard
Geese at Villafáfila, Zamora
 

The increasing attention payed to observation of large concentrations of duck and geese in Spain is being rewarded by the observation of birds showing anomalous plumages. These are being either suspected hybrids between local species or birds showing melanism or leucism.

In this page we publish a number of photos regarding the presumed hybrid mallard x red-crested pochard (Anas platyrhynchos x Netta rufina),and  a melanistic mallard Anas platyrhynchos from Llobregat delta, Barcelona, and couple of photos from two geese at Villafáfila, Zamora.

There have been other cases reported in Ebre delta, Tarragona, involving Anas strepera x sp. and different plumage variations of Coot Fulica atra.

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The presumed hybrid Mallard x Red-Crested Pochard.
Photos by Ferran López

A male hybrid A.platyrhynchos x Netta rufina, was present in the Remolar-Filipines Nature Reserve, Llobregat Delta, Barcelona, from 4.12.2001 till early 2002. Note the basic mallard aspect but the rufous tones of nape, some white on sides of neck, bill colour and profile, overall tinge to head and shape of body sides all recalling Red-Crested pochard characters.

Bill profile and head characteristics are clearly giving idea of birds parents. 
Las características de la cabeza y el pico están indicando cláramente la posible procedencia de los padres. 
Les característiques del cap i el bec indiquen clarament la possible procedència dels pares de l'ànec.

When compared with a pure Mallard, the shape of bill and the reddish-brown tinge is clearly discernible. 
En comparación con un ánade azulón puro, la forma del pico y los tonos marrón rojizos son cláramente discernibles. 
Quan es podia comparar amb un coll-verd pur, era quan els tons marronosos-vermells i la forma del bec es podien apreciar millor.

The Mallard x Red-crested Pochard hybirds looke like an abnormal Mallard (Randler, 2001: Alula,3: 82-91) and this bird fits well what it is described in the above bibliography. Los híbridos de ánade azulón x pato colorado parecen azulones raros (Randler, 2001: Alula,3: 82-91) y de hecho, este ave se ajustaba perfectamente a lo descrito en la bibliografía referenciada. Els híbrids de coll-verd i xibec semblen coll-verds rars (Randler, 2001: Alula,3: 82-91) i de fet aquest ocell s'ajustava perfectament al que es descriu a la bibliografia a dalt esmentada. 

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The Melanistic Mallard
Photo 1 by Ferran López, 2 by Ricard Gutiérrez

From 27.9.2001 (Ferran López, Xesco Macià) to 10.10.2001 (Pedro Bescós) a melanistic Mallard Anas platythynchos was also seen at Remolar-Filipines reserve, Llobregat Delta, Barcelona, Spain.

The bird was an overall black duck of the same size than the neighbour mallards, but close examination of obtained images revealed a hint of the speculum still present at least in the left side of the duck. 

The obvious pitfall for this bird identification is the drake American Black Duck Anas rubipres, that, interestingly, had also been recorded in this reserve on 14.11.1996 (R.Gutiérrez, FX Santaeufemia, M.Lockwood, J.Figuerola, F.López, accepted report, see the 1996 CR/SEO rarity report for the original record).

However, a number of characters, eg structure, size or bill colour plus colour of speculum can rule out safely the american species.

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Geese at Villafáfila, Zamora
Videocaptures by Delfín González

Villafáfila, Zamora, has held important numbers of geese, including many rarities. Amongst the odd birds, there have been the following, depicted below, which have turned to be leucistic Greylag geese and in the lower photo case, a possible either escaped/feral goose or a kind of leucistic Swan goose Anser cygnoides. In any case, only detailed descriptions can rule out confusion with other rarer species such as Snow Goose Anser caerulescens.