Thursday, 1 January 2015

An arrival of LITTLE BUSTARDS.....

An influx of Little Bustards......

Following sightings of single LITTLE BUSTARDS in Dorset at West Bexington on 18th November (Mike Morse) and in East Sussex on East Guldeford Levels on 30th December 2014 (Alan Parker), a third individual was located on New Years Eve in East Yorkshire just NE of Fraisthorpe, SSW of Bridlington. This beckons the question - do they all derive from the reintroduction programme ongoing in SW France or are they genuine immigrants arriving from record high populations in the east?

At first, I was pretty convinced of the former logic, with the two birds appearing on the South Coast - a direct target for post-breeding dispersal of French youngsters. However, with the appearance of two in two days at the classic arrival time of late December, and following a period of intense cold weather in the east - it may be perhaps best to treat them as natural arrivals, particularly as all three show no evidence of rings or tagging.

This latest bird presumably arrived fresh in from the North Sea on 31st December 2014, where local birder Kevin Barnard discovered it close to the beach at around 0850 hours. It soon flushed and flew inland but a sharp-eyed Tony Dixon soon joined in with the search, having been phoned by an extremely excited KB, and relocated it with European Golden Plovers in a grassy field nearby. Jittery as they always are, particularly in an area frequented by dogwalkers, the GP's were soon off, in turn sparking fright in the bustard. Desperate to get proof, TD fired off a number of flight shots and in doing so, lost the bird as it whistled rapidly inland. As luck would have it, the young Little Bustard was distracted by a large field of Kale and crash-landed into it, sparking off one of the biggest twitches this side of the Millenium.

The field was beside the single-track lane leading to the sea from Fraisthorpe hamlet and owned and managed by Auburn Farm and was an instant attraction to the vagrant vegetarian. Once pinned down, it remained on view from late morning until dusk, allowing an estimated 280 birdwatchers to connect before nightfall, representing the first Yorkshire record since November 1956. As expected, it remained in the same spot in the field overnight, delighting an estimated 1,200 further observers on New Years Day 2015. Perhaps due to a strong wind, the bird barely budged a few inches, deciding to stay low in the Kale, every now and again taking advantage of a few bugs on the plant leaves. It was about 100 yards in from the lane.

Plates 1-8: first-winter Little Bustard, Auburn Farm Kale Field, Fraisthorpe, East Yorkshire, 31 December 2014 (Tony Dixon)

The Reintroduction Problem
The Little Bustard has declined rapidly across European farmland landscapes due to agricultural intensification. In France, the number of breeding males in agricultural habitats has been reduced by 92% in 30 years as a result of decreases in insect abundance and nest destruction during harvesting. As a result, an age and sex-structured stochastic metapopulation model was formulated for the remaining population in south-west France and, using actual estimates of demographic rates obtained after 1997, its extinction risk over the next 30 years was estimated to be very high. Limited population reinforcement has thus appeared as a potential conservation strategy for this species in agricultural habitats, while agro-environmental actions have begun to have an effect on habitat quality at the landscape level. Different strategies for the reinforcement of fledglings, including the number and frequency of releases and the number of release localities in relation to four criteria for choosing the release points, were evaluated in terms of their effect in reducing the extinction risk of local populations and of the metapopulation. The reinforcement of 100 fledglings per year for 5 years and choosing the actual release points using the current abundance were found to be the optimal choices for reducing the estimated extinction risk of the remaining little bustard population in south-west France (Vincent Bretagnolle 2005). This project was propelled into action but found to be extremely difficult to implement, not least because the number of released young could not be sustained but that the survival rate of those released was very poor (0.04%). An estimated 760 Little Bustards were eventually released (2005-2013) but little is known of the success of the project and to date, the species in SW France remains precarious at best.

Vagrancy from the East...

In terms of vagrancy in the UK and elsewhere in NW Europe, we really must look towards the east for answers. The species has two widely separated breeding populations. In the east, it occurs in Russia (25,000+), Georgia (60 non-breeding individuals; Ernest Garcia, 2007), Kyrgystan, Kazakhstan, where the population is estimated to be 20,000 and increasing (N. Petkov, 2012), the Ukraine (100-110 individuals; Andryuschenko, 1999), NW China (very few), northern Iran and Turkey (negligable populations). In the west, its range covers Spain (71-147,000 individuals; Garcia de la Morena et al, 2006) and Portugal (17,500 displaying males; Ernest Garcia, 2007), with smaller populations in Italy and France (up to 1,875 displaying males in 2008). Eastern populations winter from Turkey and the Caucasus to Iran, and east to China, with Azerbaijan holding the largest population (over 150,000 individuals in 2005-2006 [Gauger 2007, E. García in litt. 2007]) and sightings in the winter of 2010 report 25,000 and 50,000-70, 000 individuals in Adjinohur valley and Shirvan National Park respectively (Gauger and Heiß 2010). Western populations winter in the Mediterranean zone, with the Iberian peninsula holding the most important wintering quarters (a minimum of 16,429-35,929 and 11,200 individuals in Spain and Portugal, respectively) (E. García in litt. 2007). The global population (excluding Kazakhstan) was estimated at a minimum of c.240,000 individuals in the late 1990s (C. Martínez in litt. 1999), but it may be substantially lower than this, due to the re-evaluation of the size of the Spanish population (García et al. 2007). Whilst it remains widespread and numerous, in some parts of its range it has declined dramatically since the 19th century, leading to extinctions in at least 11 European countries, Algeria, Tunisia and probably as a breeding bird in Azerbaijan. The species has now disappeared from mainland Italy, where it occurred in Apulia, and it is presently declining in France and Spain (V. Bretagnolle in litt. 2007). In Portugal, the population appears to be stable, and eastern populations are said to have increased in recent years (E. García in litt. 2007). The population in the Eurasian steppe belt is thought to have recovered due to an increase in fallow land during the transition process of the former Soviet Union (Gauger 2007) (Birdlife 2013)

No comments:

Post a Comment