Sunday, February 1, 2015

Wire-hoppers, long-distance migrants - and your list...

I would be prepared to wager a fair mound of money on the notion that the topic that raises the most discussion and controversy among keen birdwatchers is the difficult subject of escapes. A substantial amount of stress could be eased if captive birds would just stay where they were, but accidents happen. Cages get damaged in storms, pairs breed and their young depart before they can be banded or pinioned, a whole range of events can take place. And before you know it, a bird has turned up where it is not expected. Of course, if this bird were to be something like a kiwi or an ostrich, we wouldn't get too excited, for these birds are never likely to appear too far out of their normal range. No, the problem comes when there is an outside chance that the bird may be a genuine vagrant; a wanderer from its normal range that has perhaps been blown here by an adverse wind - and therefore fair game to go on our ever-growing check lists...

An unusual bird turns up and the hotlines start to vibrate. Facts can often be hard to come by, so opinion starts to hold sway. The list serves start to heat up; the meek give way and sink into the shadows; the discussion becomes a disagreement, becomes an argument; becomes pistols at dawn!!

But this is such a shame, for the only reason that such discussions get so heated is almost always because we put our lists before our interest in the bigger picture. Almost always, the problem starts with a duck or a goose, for these birds are extremely popular in captivity, difficult to keep penned, and thus prone to escaping relatively regularly. In addition, wild populations of such birds often are long-distance migrants and thus prone to vagrancy. The problem cam easily become unsurmountable.

 It would be easy to dismiss any occurrence of an out-of-range duck or goose as not worthy of our attention. But, if we are generally interested in the vagrancy potential of birds, then we need to address the occurrence of such birds on an individual basis. And above all, we need to put our desire for a 'tick' on one side for a moment. It seems to me that the real sticking point is that there really seems to be no one single argument that categorically nails the exotic visitor one way or another; discussions revolve around several issues: is the bird banded? Does it show signs of captivity? Is it tame?

Can these questions help? It would seem not. A caged bird can escape before the owner has had time to apply a band (this shouldn't happen, but it does). Some observers look for extreme feather wear, or abrasion to feet or bill to suggest a captive origin - but visit a cage bird show and you will see perfect birds on display - the pride and joy of their trophy-winning owners. Is the bird tame? Not always a good sign, one way or the other. St James's Park in London has a mass of ducks on it in the winter, all readily coming to take bread from the visiting tourists - and yet such ducks often include individuals carrying bands that show they were trapped as wild birds in Russia during the breeding season!

So why do I bring this up now? Well, it's been an interesting winter again in New Jersey for unusual wildfowl. Barnacle and Pink-footed Geese have shown up in Canada Goose flocks in central Jersey, while Cape May currently hosts a wonderfully exotic Ruddy Shelduck, again in a flock of migratory Canada Geese. What to do? The geese, perhaps seem a little more straight forward. There is evidence for Canada Goose populations spreading eastward and establishing breeding populations in western Greenland - this seems to be because the region is become increasingly ice-free during the summer, courtesy of global climate change. At one time, such birds seemed to be considered guilty until proven innocent by regional records committees (for it is they that have the unenviable job of proclaiming on these things), but now a more liberal approach seems to hold sway. Certainly it is easy to see how Pink-footed or Barnacle Geese from eastern Greenland can find themselves tied up with Canada Goose flocks and then head south with them on the fall.

Rarity chasing will always be an attractive prospect and is a great excuse for visiting new places. If it wasn't for this Barnacle Goose, I wonder if I would ever have visited North Branch Park in Somerset County! Barnacle Geese are great birds wherever you see them and well worth seeing wherever they show up [photo by Mike Crewe].

Horses for courses... What species of  bird draws the attention of local birders will, of course, depend on where you are. While US birders chase Pink-footed Geese in Canada Goose flocks, British birders chase Snow Geese in Pink-footed Goose flocks - and the same arguments ensue! This Snow Goose was one of two in a flock of some 3,000 Pink-feet in Norfolk, UK in January 2006 [photo by Mike Crewe].

But what of a Ruddy Shelduck? Well, the long and the short of it is, we will almost certainly never know. This is a popular bird in captivity, but the species has a track record for vagrancy; indeed, it has probably been given short shrift in the past and unexplained groups of three or more birds have been noted in a number of unexplained occurrences in some far-flung places. Some years ago, I saw one feeding on the tidal flats at Nesseby, a picturesque little village half way along Varangerfjord in far northern Norway. Similarly - and even more intriguingly - a party of six Ruddy Shelducks was discovered on Southampton Island, Nunavut in July 2003. Escapes? Certainly the latter birds have not been accepted by the relevant records committees, but genuine vagrancy seems far more likely than a mass break-out of six birds that then decided to head into the far northern Canadian Arctic!

Ruddy Shelduck at Lake Champlain, Villas, Cape May, January 2015. Whether it is wild or not, a Ruddy Shelduck is a great bird to see. This is an adult female, as shown by the extensive white on the head and the lack of a black neck ring. In most species, juvenile/first-winter birds seem most prone to wandering, so is it a bad sign for our lists that this is an adult? [Photo by Mike Crewe]

So why worry? Does it really matter whether these birds are escapes or not? Well I guess it depends on how interested you are in birds (I've moved on from lists now!). There are certainly implications for conservation. The greater New York area hosts a number of growing populations of Monk Parakeets; at the most basic level, these free-ranging, self-sustaining populations give us an extra bird for our lists, but what are the implications for the region? Are the birds having any adverse affects on the local habitats - competition with other bird species, potential effects on plant species that they might feed on? And what of their impacts on the Human environment? Should we be more concerned with the fact that they brighten up a dull day with their bright colors, or should we consider the potential problems that their nests might cause to utility wires?

Monk Parakeets at Carteret, New Jersey. A cheerful addition to the list, or a reason for concern? Research based on sound recording and monitoring will be the best way to decide [Photo by Mike Crewe].

And is a Monk Parakeet only 'countable' if you see it where it really should be? This bird was photographed on the Pantanal in southern Brazil, in the species' home range - and yet it was happily hanging out on a less-than-natural area of cattle ranching. A great example of a highly adaptive species [photo by Mike Crewe].

Monk Parakeet nest snuggling up between plastic siding and electrical wiring in New Jersey.... [photo by Mike Crewe].

Such populations of birds may not have been deliberately liberated, but they are now out there and part of the environment. Overwhelmingly, introduced species seem to cause problems, but this is not always the case and some populations of introduced birds now form significant percentages of the world populations of some species.

Clearly this is a multi-faceted issue, so how can we, as birders help with the bigger picture? Well there is a strong argument for recording any bird that turns up, escape or not. For if we are armed with all the facts, making informed decisions becomes so much easier. If the very first Monk Parakeet turns up and is recorded, in the future we can look back at, say, 10 years of data and make good judgement calls on the birds. Is the population showing signs of increasing rapidly and thus indicating the potential to be difficult to control should the need arise? Or do the birds seem to be levelling out and fitting into a comfortable niche? These decisions are for others to make, but we can help by recording our observations - and not worrying quite so much about our lists...

Red-legged Partridge in Norfolk, UK. This species was originally introduced into the UK for hunting, then started to become 'hybridized out' when the closely-related Chukar was also introduced. With natural populations of Red-legged Partridges seriously declining throughout its range in France and Spain, the UK population took on a new importance. A ban was put on the release of Chukars and now the UK population makes up a significant percentage of the world population of this species [photo by Mike Crewe].

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