A Siskin conundrum!

Las Grutas in Rio Negro province of Argentina, is in a transition zone regarding both habitats & birds. Many species reach both their southerly range on or about here & conversely other species reach their most northerly range on or around the town. Also, a few species normally associated with the Andes Mountains occur around the town, for example Chiguanco Thrush & Cordilleran Canastero.

Male Hooded Siskin

Female

The Hooded Siskin ( Spinus magellanicus) is common in parks & gardens in the town. We were there in late autumn/winter & this species was found in quite large flocks both in the town & on the edge of town, where the Patagonian scrub habitat started. We also recorded it occasionally deep in the Patagonian scrub habitat, but it was much rarer here.

Black-chinned Siskin (Spinus barbatus) is normally associated with the Andes, but is also found in & around Las Grutas. We found it to be rare during our period of observation, with only a couple of records on the edge of town. However, there are many records on e-bird of this species both around Las Grutas & further south along the coast. I didn't manage to get any photos of this species.

Silvestrin type Siskins

Notice the lack of black on the head 

& a pale supercilium

Notice the almost lack of yellow in the wing.

These birds are very washed out.

Yellow, when present is feint & diffused.

However, there is a third type of Siskin found commonly around Las Grutas. This is the so-called Silvestrin Siskin. This type (species)? has been known about for quite some time, at least ten years. But I am not aware on any systematic work on it. It is still not known if it is a distinct species, or just an un-described race of Black-chinned Siskin. 

It is certainly quite common in the Patagonian scrub habitat that surrounds the town of Las Grutas. It was usually found in small parties of between 6-8 birds. We found it to the north, west & south of the town, we also saw it in dune vegetation habitat just south of Las Grutas. We never saw it associating with other Siskin species (although this is likely to happen) & we never recorded it in the town itself. However, we did see it right on the edge of town on two occasions, both times in Patagonian scrub.

Now we have a problem!

Silvestrin type Siskin, but with a darker crown!

There is also dark grey around the 

sides of the head.

But the overall greyness to the plumage is apparent.

Minimum yellow in the wing.

If one consults The Birds of Chile by Jaramillo, he mentions a grey morph occurring in both Hooded & Black-chinned Siskins & he illustrates them. But the birds he illustrates have much more yellow in the wing & indeed a more yellow tone to the overall plumage. It would be easy to dismiss the above photos as immature/female type Black-chinned or Hooded Siskins, apart from they normally don't look like that! Also one sees flocks of them all looking the same & some of these non-descript birds singing! All possibilities are still on the table. A bit of a puzzle at this time.