On November 20, 2005, after a bird ringing session in Paul de Tornada,  Pedro Henriques and myself, decided to go to the Bay of S. Martinho do Porto (west Portugal), to take a look at the gulls. It was especially interesting because Common gulls (Larus canus) (uncomon in Portugal) and Ring-billed Gulls (Larus delawarensis) were relatively regular at this site during the winter. Sometimes 4 or 5 inds. of each species, simultaneously.

Soon as we arrived, we noticed a striking first winter Franklin´s gull (Leucophaeus pipixcan) among Black-headed gulls and a Ring-billed gull. I was still recoverying from finding a Laughphing gull, two weeks before in Peniche.

13 years ago I had a Canon analogic camera with a 70-300 lens, to update my ebird I just scanned the printed photographs, and here they are:

At the beginning of February 2019, in one of my regular incursions to the Óbidos Lagoon, I found two Greenshanks (Tringa nebularia). The birds were relatively close, feeding on the edge of the pond. I took some photos with the purpose of practicing ageing Greenshanks, at a time of the year when it is more difficult.

I have always found, with some exceptions, relatively hard to age waders. The great variability in feather patterns and the intensity and extent of moult, makes some plumages difficult to interpret.

Summary of the moult in Greenshanks:

Adults

Post-nuptial - Complete. A part of the individuals begins primary moult still in the breeding grounds and suspends it during migration, resuming it in the wintering areas. Others begin primary moult already in the wintering areas.

Pre-nuptial - Partial. Variable, but usually includes replacing body feathers, some coverts and tertials.

Juveniles

Post-juvenile - Partial. Includes a variable number of coverts, body and tail feathers.

Pre-nuptial - Partial. Variable, but, as in adults, it can include multiple coverts, tail feathers and tertials. Some birds can moult outer primaries (Prater, et all, 1977).


The separation of 1st winters from adults, in autumn, is relatively easy. One of the most mentioned characters in the literature is the shape of the median coverts. Where the typical median covert has a clear pale fringe, interrupted at the tip by a brown split (Fig. 2). The bird in Fig. 1 is a 1st winter that has undergone a post-juvenile molt restricted to the scapulars, and most likely, during autumn, will replace a variable number of lesser, median and greater coverts. The tertials are juvenile, told by the brownish coloration and weak pattern, but some individuals can present gray tertials with a more defined pattern.

At the beginning of the winter, juveniles have already renovated a good part of the coverts during their partial post-juvenile moult, resembling adult plumage. Knowing that adults undergo a complete post-nuptial moult, to identify immature birds one must look for juvenile feathers that remain unmoulted. This task is increasingly complicated as winter progresses, mainly because feather wear tend to blur significant differences in plumage patterns.

One factor to take into account is the inferior quality of juvenile feathers, that lead to a slightly more pronounced wear than in adults. This wear is particularly evidenced by the coloration. For example, lesser and median coverts tend to be browner in immature birds than in adults.

Another feature that can help separating age groups at the end of winter is the wear, shape and coloring of primaries and secondaries. In my opinion, this is one of the most reliable characters, since it is less subject to variability than the coverts. Given the Greenshank moult pattern, immature should keep juvenile primaries, sometimes until the next complet moult (August-October). Some caution is needed during spring, as there seem to be some immature birds that renew the outer primaries, which would result in birds presenting the tip of the  primaries "fresh", when observed in the field. In this case, a photograph with an open wing is required to see the moult limit, between the outer primaries (adult type) and the inner primaries (juvenile).

The two birds, I observed in Lagoa de Óbidos, showed a slightly different coloration of the upper parts. The bird 1 (front in the photo), presented grayer shades in most coverts, I classified this bird as adult. The bird 2 (back in the photo) had some brown coverts, as well as flight feathers, a little more worn, I classified this bird as immature (2nd calendar year).

In this photo we can see the head pattern, which is slightly different in the two birds. Bird 1 (front in the photo) features a whiter throat and bold gray stripes on the side of the neck . On bird 2 (back in the photo) the stipped pattern on the neck is thinner and less defined, creating a less "clean" appearance of the head and neck.

Bird 1 (front in the photo), also has two tertials, in the left wing, very "fresh" and gray. I am not sure if they were renewed in a late post-nuptial moult or in the pre-nuptial moult. Therefore, it is quite possible that the bird is in active moult of coverts and / or body feathers.

Bird 1 -  Flight feathers with little wear, presenting a well defined white edge in secondaries and  inner primaries. The upper parts have a greater uniformity of coloration, with the lesser and median coverts dark gray.

Bird 2 - Primaries and secondaries with some wear, showing a weak white trailing edge.  The upper parts have areas with light brown coverts, particularly in lesser and median coverts. Note the  innermost great covert of the right wing, showing a good amount of wear.

Comparison of the shape and level of wear on the primaries and secondaries. (Bird 2 - left, Bird 1 - right). Note the broader upper edge of the flight feathers on bird 2, creating a more "blunt" tip, characteristic of juvenile feathers.

The wear and pattern of the tail feathers, in particular of R1 and R5, has been mention out as a way to separate juveniles and adults. I believe it may work in some inds., although In the case of these two birds, from what I could perceive in the field and in the photos, it seems to me that both replaced the tail feathers, making it useless as an ageing criteria. 

Conclusion

Ageing Greenshanks in late winter, or early spring, can be a tricky task. The extent of post-juvenile moult can lead to some individuals getting plumages very much like adults. So when we come across a Greenshank we should take into account the following:

- Check if there are any median coverts with the typical juvenile pattern;

- See if different generations of feathers occur in the coverts, in particular, if there are brownish feathers and with enough wear on the upper parts. There must be some caution because adults, at the end of winter, can also exhibit different generations of feathers, as a result of partial pre-breeding moult. Immatures will show old brownish feathers, not gray;

- Observe the wear on the primaries, if it has wear, the bird should be an immature;

- In the literature it is mentioned that some immature birds can moult the outer primaries in the pre-nuptial moult. I do not know exactly how much this happens in the populations that winter or migrate through Portugal. So, if a bird in late winter, or early spring, displaying "fresh" primaries tip may be an immature one. In this case, it is necessary to check for juvenile coverts or, if an open wing photo is obtained, if there are moult limits on the inner primaries.

- If you get an open wing photo, we can also observe the shape of the primaries and secondaries, which apparently seems to be different in adults and immature birds (I need to test this theory better);

- To verify the wear of the tail feathers, some juveniles seem to retain some tail feathers in the post-juvenile molt.

Acknowledgments

To Peter Potts, Pedro Lourenço and Leila Durte.

​On the morning of February 1st 2019 mainland Portugal was beginning to feel the effects of the depression "Helena". The day broke with showers and moderate SW wind. I decided to go to Peniche, one of my local patches, to take a look at seabird movement and check the gulls. To my pleasant surprise there was a Glaucous gull (Larus hyperboreus) resting among a group of Lesser black-backed gulls (Larus fuscus) and Yellow-legged Gulls (Larus michahellis), at the mouth of the Saint Domingos river.

Although I have observed this species several times in the past, particularly during the winter influx of 2013/2014, I had never observed this plumage. The bird, at first sight (and light conditions), had an adult appearance with a gray mantle and light iris, but with an immature bill. The bird was kind and allowed me to spend some time studying and photographing the plumage details.

The bird had a pale pink yellow bill, with a dark, relatively well-marked, subterminal stripe. The tip was ivory. The legs were pink, more intense than the beak. The iris was pale olive and had a dark pre-ocular mark. Note the pale brown infusions on the side of the chest, extending to the nape.

The third left tail feather (R3) presented a slight brown infusion along the shaft.

The coloration of the primaries begins to approach the adult pattern, however, it presents with a less obvious division between the white of the feather tip and the interior.

A good portion of the innermost greater and median coverts, as well as the  tertials,  were white.

In flight we can observe the marbled pattern formed by the contrast between the white and buffish coverts and the gray.

The underwing coverts presented creamy tones in the median and lesser coverts, forming a slight brownish bar, which contrasted with the white axillaries.

​At the beginning of June 2018, we decided to go for a week of family vacations on the island of Madeira, with a day in Porto Santo. This would be my first visit to the islands. Although bird watching was not the main objective, whenever there was an opportunity, I kept my binoculars up. I was particularly interested in seeing Trocaz pigeon and Madeira firecrest. I also had the opportunity to do a four-hour pelagic trip off Funchal,  with Birds & Company. The pelagic trip proved to be a success, and is, undoubtedly, an excellent addition to the itinerary for any birder that visits Madeira. Species like the White-faced storm petrel and two putative Bugio petrel made the boat trip unforgettable. Sadly I did not have the chance to see the elusive Zino´s petrel (Pterodroma madeira).
 
This article is intended to be an annotated checklist of bird species observed during my trip to Madeira and Porto Santo islands.

1. Petrel (Pterodroma sp.);
Probably Bugio petrel (P. deserta), two inds. were observed during the pelagic trip (June 5th). Unfortunately I could not get any photos.

2. Bulwer´s petrel (Bulweria bulweri)
About seventy inds. observed during the pelagic trip, some very close to Funchal. More birds observed during the ferry crossing to Porto Santo.

3. Cory´s shearwater (Calonecris diomedea)
Fairly abundant during the pelagic trip.

4. Manx shearwater (Puffinus puffinus)
Ten inds. observed during pelagic trip.

5. White-faced storm petrel (Pelagodroma marina)
One ind. came to "chum" during the pelagic trip.

6. European storm petrel (Hydrobates pelagicus)
One ind. came to "chum" during the pelagic trip.

7. Little Egret (Egretta garzetta)
One ind. at the river mouth of Câmara de Lobos.

8. Eurasian Sparrowhawk (Accipiter nisus granti)
One ind. at São Vicente river valley.

9. Common Buzzard (Buteo buteo)
Two inds. observed at Ponta do Pargo.

10. Common Kestrel (Falco tinnunculus canariensis)
One ind. observed at Ponta do Pargo.

11. Atlantic Yellow-legged Gull (Larus michahellis atlantis)
Several inds. at beaches and ports.

At the beginning of January 2019, I found two Richard´s pipits (Anthus richardi) in one of my local patches: the fields next to the Sewage treatment pond, close to Peniche town, West Portugal. The presence of Richard´s pipits, during the winter in these fields, has been anual. This autumn, one of the fields has been plowed and the pipits spend some time feeding off of the tall grass. They feed particularly on earthworms. With the scope and the folding chair in hand, I spent some time having fun studying the behavior and moult pattern of these two individuals.

Moult in Richrad´s pipit
 
Post-nuptial (adult): It is complex and variable, but seems to follow 3 different strategies:
 
1. Birds that undergo a complete moult on the breeding grounds (July-September)
 
2. Birds that suspend moult and resume it on the wintering grounds.
 
3. Birds that undergo a complete moult on the wintering grounds.
 
Post-juvenile: Partial moult that may be more or less extensive. Often the partial moult involves the replacement of head and body feathers, leaving the mantle, rump and upper tail coverts unmoulted. The moult usually includes a variable number of coverts (lesser, medium and, less extensively, greater coverts). Sometimes the moult also includes a few tertials and tail feathers.
Between October and January may occur an "additional" moult, in which some birds can replace some body and tail feathers, tertials and greater coverts.
 
Pre-nuptial: Many birds, both adults and immatures, perform a partial pre-nuptial moult, which usually involves the body, some coverts and tail feathers.

The birds of Peniche
 
The two pipits were notoriously different in coloration, which made it relatively easy to know exactly which individual I was observing in each moment. The birds spent some time actively feeding close to each other, which allowed a direct comparison with the same light and angle. Although sometimes the photos may slightly alter the colors, they seem, in this case, quite faithful to what I observed in the field. Ind. (A) was generally paler. The underparts were white with buffish infusions, almost restricted to the lower flanks. The back was pale with dark spots, formed by the center of some mantle feathers. The birds, despite the distinct appearance, were both immatures (1st winter), revealed by the pattern, color and wear of some greater coverts.

​
Moult extension in Ind. (A)
​
Ind. (A), was notoriously paler. I believe it was due to having made a partial post-juvenile moult before migration, which causes the plumage to wear out. The moult, from what I could observe, seemed symmetrical. This bird had three different feather generations: juvenile feathers, which apparently included the primaries, secondaries, primary coverts and most of the greater coverts; feathers acquired in the post-juvenile moult (pre-migration), which included medium coverts, a single greater covert (Gc 10), a tertial (T8), tail feathers (R1 and apparently R2); the scapulars and lesser coverts seem to have been replaced in a recent post-juvenile moult, early in winter.

(1) - Visible median coverts, replaced in the post-juvenile moult, they have a broad, and yellowish border that gradually merge into dark centers.
 
(2) – Greater coverts nr. 1-9, with juvenile pattern, presenting a thin and white border.
 
(3) – Greater covert no. 10, looks like it was replaced during post-juvenile moult. The center of the feather is darker and the border exibits a broader and yellowish coloration when compared to other Gc.
 
(4) - The scapulars and lesser coverts seem to belong to  a different, more recent, generation. Judging by the little wear and tear, the moult of these feathers may have occured in the wintering grounds. I did notice a more vivid coloring, even standing out from the rest of the plumage.

​(5) – Shorter tertials (T9), still juvenile, light brown and very worn.
 
(6) – Central tertials (T8), replaced during post-juvenile moult, showing similarity in color and level of wear with the Gc 10. Although it ‘s difficult to see in the photos, I had the feeling that both T7 were still juvenile.
 
(7) - Primaries and upper tail coverts stilll juvenile.
 
(8) - The central pair of tail feathers (R1) was replaced during the post-juvenile moult and apparently the R2, right and left, as well.
 
Body moult - Apparently the bird moulted some feathers of the back, head and underparts during the post-juvenile moult. It is difficult to assess the extent of this moult without seeing the bird in the hand. However, due to the faint pencil streaks on the breast, mustacial and malar stripes, there was no head or chest moult during early winter.

​Moult extension in Ind. (B)

Compared with Ind. (A) this bird was darker and had the majority of the plumage in good condition. Apparently, Ind. (B), underwent a post-juvenile moult in early winter. It’s difficult to know for sure if this bird has replaced some of the coverts in a post-juvenile moult before migration, but it is likely, that if it occurred, to have been very limited. The tail feathers were in active moult, so, given the good state of conservation of the plumage, the bird may still be finishing the early winter moult.

​(1) – The median coverts were recently replaced in the early winter moult, exception could be the median covert no. 4. Compared with the other adjacent coverts, it appears to have a paler edge and a more faint center. Also visible is one unmoulted juvenile lesser covert (Lc).
 
(2) –  The greater coverts nos. 1-7, the primary and the carpal coverts are also juvenile.
 
(3) – Greater coverts nos. 8, 9 and 10 have been recently replaced,  it’s possible to tell it by the buffish border gradually merging into the dark center of the feathers.
 
(4) - Tertials T9 and T7 are juvenile, but the central pair (T8) was recently replaced.
 
(5) – Juvenile primaries. I cannot rule out the possibility that some inner secondaries may have been moulted, sadly I could not confirm this.

​6) - The back pattern is noticeably stronger and more striped than in Ind. (A). The feathers of the mantle and rump seem to have been replaced recently.
 
(7) – Juvenile right tail feather (R1). The left tail feather (R1) appears to be missing and the left R2 is growing, already about 3/4 of the way.
 
Body moult – Judging by the pristine condition of the feathers and vivid coloration, there was (or is still active) a relatively extensive early winter body moult. The well marked chest, moustacial and malar stripes reveal that the moult also included the head and chest feathers. The flanks were deeply buffish.

​Just for fun, some sound recording...
​
It was possible to record flight calls of both birds. Here it is.

​Bibliography
​
Alström, P, Mild, K & Zetterström, B 2003. Pipits & wagtails of Europe, Asia and North America: identification and systematics. London.

Svensson, L 1992. Identification guide to European passerines. Fourth edition. Stockholm.