THE BLACK STORK IN EXTREMADURA

TRANSLATED BY MARTIN KELSEY

Despite being a very attractive species for birdwatchers, the unusual and isolated Iberian population of Black Stork (Ciconia nigra) continues to be poorly known. Indeed, the only national census carried out in Spain took place way back in 1987. Since then, there have only been some compilations of information from varied sources. From these early estimates, the population in Extremadura (161-219 pairs over the period 1995-2013) has always been the largest. Portugal follows, with between 97-115 pairs in a national census carried out in 2004, and Andalucía, with 87 pairs in 2009, all of them in the Sierra Morena. With pre-2003 figures, we have Castilla y León (61 pairs), Castilla-La Mancha (24) and Madrid (12). Adding this all together, admittedly over a long time frame, produces 470 pairs for certain in the Iberian Peninsular, although it is likely that the real figure exceeds, probably by a margin, 500 pairs. If one takes into account published data, the Iberian population has apparently increased (Cano y Hernández, 2003, cited 405 certain pairs). If there had been a better coverage, it is probably wiser to consider the population as stable. For example, in the case of Andalucía, where a figure of 54 pairs (2006) and 52 pairs (1999, 2005, 2007) rose to 89 pairs (2009), an increase of no less than 70% in two years, which seems improbable under natural circumstances. 

 

Focusing on the population in Extremadura, the graph below shows the values obtained in 17 regional censuses that we have been able to compile. Two phases can be seen, the first between 1973 and 1989, when ornithology in Extremadura was in its infancy and the data are partial, mainly anecdotal. And the second phase from 1993m the government of Extremadura started annual counts. The studies undertaken by Adenex (José Luis Pérez-Chiscano, Víctor Pizarro, José A. Román, Juan J. Ferrero and others) have also helped. The information of these last twenty years shows a stable trend, with peaks and troughs most likely because of differences in effort and coverage (there are variations of up to 21% between consecutive years). The maximum figure was 219 pairs in 1995, followed by 195 pairs in 2011. In 2013, the census recently made public reached 189 certain pairs , 30 less than the maximum twenty years ago. By province, 116 pairs were found in Cáceres and 73 in Badajoz (in 2003 there were 101 and 82, respectively). Taking into account that censuses almost always underestimate real populations, it us very likely that there are more than 200 pairs in Extremadura, perhaps even 220.

The map shows the breeding distribution of Black Stork in Extremadura. The areas of highest breeding density are shown in red: the dehesas of south-west Badajoz, Monfragüe, Alagón, the Tiétar pinewoods and areas in along the Tajo and Guadiana rivers. This area of occupation remains practically the same since the first censuses, being centred along the Tajo river and its tributaries, and in some areas of dehesa and mountains.

With respect to breeding, we have information from 2002 and 2013. In 2013, 147 nests were monitored, from which 290 young fledged. The reproductive indices are very similar in both years:

- productivity (fledged young per occupied nest): 1.97 in 2013, 2.05 in 2002.

- fledging success (fledged young per successful nest): 2.45 in 2013 and 2002.

- Percentage of pairs which raise young successfully: 82% en 2013.

These figures for Extremadura are very similar to the average for Spain as whole (1.94) and elsewhere in Europe (1.81 in Latvia, 1.96 in Lithuania) (Cano, 2012).

An interesting aspect of the Iberian population of Black Stork is the high proportion of nests built on rock. The Black Stork normally nests in trees across its wide range across Europe, although there are countries where use of rocky sites is significant (Austria 28%, Bulgaria 52%). The distant population in southern Africa nests exclusively on rock and the isolated Iberian population has a figure of 55%, with 75% in the case of Portugal. For Extremadura detailed information of nest substrate use is given for the years 2003 and 2013 (table). Nests on rock reach 55%, the same as the Iberian population as a whole, with somewhat more use of this substrate in 2003 than in 2013. It is noteworthy that whilst the population, distribution and breeding success has remained stable over the last decade, there are important changes in best sites. There has been a drop in the number of nests in cork oak by a third, compensated by an increase in tree nests in general, especially in holm oak and pine. With respect to rock sites, there has been an increase in use of rocky valleys, now the habitat most often used, with a decrease in sites in mountain ranges.

These changes in nest sites deserve a more detailed analysis to determine the conservation impact of the Black Stork as well as the Cork Oaks themselves (are there fewer Cork Oaks of sufficient size? Has their management changed? Is there more disturbance?). Over the last decade there at least has been more information on the conservation of Black Stork. Some of us remember that in 2003, at a regional congress, Pizarro et al. cited seven nests that were destroyed by fire that year (three in the dehesas of Jerez, two in the Tiétar pines, one in Cañaveral and one in Sierra de San Pedro) or how the construction of the Alqueva dam apparently caused the loss of ten active nests; also they stated that half the nests in cork oak suffered disturbance during the cork harvest and during pruning; and how sensitive nests were to boat traffic on rivers, indeed that there were no nests on navigable stretches. And not forgetting the damage caused by changing water levels on reservoirs, with 23 nests and 25 chicks lost in 1994.

Acknowledgements: This post is based on information published in the sources cited below. The 2013 data come from a press release from DGMA-Junta de Extremadura, apart from the nest site data which have been provided Ángel Sánchez/DGMA (in litt.). The censuses in Extremadura are carried out every year by some 250 rangers and other staff of the Environment Directorate. We also would like to extend our thanks to personnel in Portugal and other parts of Spain, as well as to other fieldworkers and volunteers who have collaborated.

References:

• Anuarios Ornitológicos de Extremadura. 1998-2008.
• Informes de Medio Ambiente en Extremadura. 2006-2012.
• Censos oficiales de la CMA-Junta de Andalucía.
• Cano, L. S. 2012. Biología y conservación de la cigüeña negra en la península Ibérica. Tesis Doctoral. Universidad Complutense de Madrid.
• Cano, L. S. y Hernández, J. M. 2003. Cigüeña negra Ciconia nigra. En Martí, R, y del Moral, J.C. (Eds.).Atlas de las aves reproductoras de España. MMA y SEO/BirdLife. Madrid.
• DGMA. 2004. The black stork in Extremadura, Southwest Spain. IV Conferencia Internacional de cigüeña negra. Dávod-Püspökpuszta. Hungría. Abril 2004.
• Ferrero, J.J. y Pizarro, V. M. 2003. La cigüeña negra en Extremadura. Cuadernos Populares 61. Consejería de Cultura. Junta de Extremadura. Mérida.
• Pizarro, V. M., Fererro, J. J. y Gil, A. 2003. Conservación de la cigüeña negra en Extremadura. II Congreso de especies protegidas de Extremadura. 19-21 noviembre 2003. Cáceres. DGMA. Junta de Extremadura.

RESERVOIRS OUT OF CONTROL: BLACK STORK NESTS FLOODED

Black Stork (Ciconia nigra). Monfragüe National Park, flooded nest in 2007. By Miguel Ángel Muñoz "Memole".

The irregular rainfall of the Mediterranean climate, for better or for worse, governs Extremadura and especially so in 2013. In spring we were blessed with one of the wettest on record, filling the reservoirs to levels never seen before. The Tajo, which used to be a river is now an uninterrupted chain of reservoirs established almost exclusively for power generation. It is a resource for everyone, used by one of the biggest multinational power companies without respect for legislation pertaining to the protection of species and protected areas. In April (see photo below), voices were already being raised in alarm because the Alcántara reservoir was rising and threatening some of the most famous Black Stork (Ciconia negra) nests in the Monfragüe National Park. Even though the Confederación Hidrográfica del Tajo and Iberdrola had been advised, this was ignored and water was released upstream from the Valdecañas reservoir, with grave consequences for the colonies of birds nesting there on islands (so much so that by mid-June, the islands became connected to the shore and dozens of chicks died and many clutches were lost), the water level in the Alcántara reservoir was rising to 99% of its limit and ended up flooding active Black Stork nests in Monfragüe.

 Black Stork (Ciconia negra). Monfragüe National Park, 20th April 2013.

The image of a Black Stork chick on a wooden pallet, in the heart of Monfragüe, is shown below. This nest had two chicks, but when the Monfragüe staff intervened they found the surviving chick perched on top of its drowned sibling. Faced with this emergency, they opted to raise the nest on three pallets and other material. This nest had also been flooded in May 2007 (photo at the top of the posting), when fours chicks had to be removed and taken to the Animal Clinic at Sierra de Fuentes, Cáceres. In the winter of 2008, a new platform was installed at a higher point to try to avoid a future flooding, a solution which clearly failed this year since the artificial nest was situated below the maximum water level of the reservoir.

Black Stork (Ciconia negra). Monfragüe National Park, 8th June 2013.

These events, in Monfragüe as well as at the Valdecañas reservoir, have been denounced by SEO/BirdLife [read here] and by the authorities in Extremadura. We shall see how the story ends and if the surviving chick fledges. At the end of June the reservoir had lowered and it seemed that the youngster would be fine (see photo below), but at the start of July, alarm was raised again because the Alcántara had increased its level dangerously. We have heard that the nest has again been rebuilt by the authorities.

Black Stork (Ciconia negra). Monfragüe National Park, 19th June 2013.

The Government of Extremadura provided explanations that surprised us. On one hand it came out in defence of the multinational Iberdrola. It also blamed the rains of March, a full three months earlier, which would have had no influence over the fluctuations of level in June and July, which are exclusively due to the management decisions of the company. And finally, and as it usual, the present government put the blame on its predecessor.

Translated by Martin Kelsey.

CHONI, BLACK STORK

Black Stork (Ciconia nigra). Choni on nest "original" in 2011, last season it was observed, with an age of 21 years. Eva Palacios.

Humans name each new family member as it enters the world, but the animals that we see in our travels are all anonymous. Or almost all. Some have brand new names thanks to man marking them. Among the birds of Extremadura has been such a particular individual: Choni, a Black Stork. The legend was born of "The Choni".

Choni had the great idea of starting her home in a highly visible place in the much visited Monfragüe National Park, becoming perhaps the most famous Black Stork in the world. And all because on one of her red legs is a white plastic ring with the letters C/HN. It is now easy to see how she got her name. This author came to Extremadura in 1995, when Choni started her nest. So for over 18 years we were almost neighbors ... with me waiting for her timely return each spring. In 2012 she did not return. After a year's absence, it seems highly justified for me to write this small tribute.

Black Stork (Ciconia nigra). Choni was born in Oliva de Plasencia. Photo by J. A. Roman in 1988. There are no photos of 1990 when Choni was ringed.

Choni was born in a nest in an old corn oak in Oliva de Plasencia (Cáceres), in the spring of 1990. A productive and accessible nest where several chicks had been ringed in previous years, probably Choni's siblings. On 11 June 1990, Jose Antonio Román and Juan José Ferrero, ringers from Elanus de Adenex group, ringed the three chicks in the nest. Of the three siblings, C/HL was seen on 13 and 25 September 1991 in the Emblase de Valuengo, Badajoz, but there have been no further sightings. Worse fate befell C/HP, found dead, 2,900 km away, in Africa three years later, on June 14, 1993 in Macina, Mali.

In her fifth year, Choni, now an adult female took possession of one of the classic nests in Monfragüe, close to the famous Portilla del Tiétar and only 35 km from her birthplace. A territory held from 1994 to 2011 for 18 straight seasons where year after year she successfully raised between one to four chicks each year. We have data for 18 seasons, when she fledged a total of 46 young , ie an average of 2.55 per year. At least three different males have shared her nest. One of them, ringed as 1/9V, was her partner four years, between 1999 and 2002. This male, also born in the north of Cáceres, was ringed by Elanus de Adenex on June 19, 1992.

Black Stork (Ciconia nigra). Choni, aged 21, with her partner. Year 2011. Javier Prieta.

Black Stork. Male W[1/9V]. Partner of Choni between 1999 and 2002. By Enrique F. Larreta.

Thousands of people have enjoyed seeing Choni on her nest, resting, flying, incubating or feeding her chicks, and sometimes seeing surprising behavior, such as two cases of infanticide, and the presence of other ringed birds in or near the nest: a juvenile from Luxembourg on September 18, 2004 (O [CT05]), a bird born in 2005 Lanzahíta, Avila was seen on 18 and 23 March 2008 (W [68C4]), and one born in Valdemaque, Madrid in 2005, was observed on June 12, 2010 (W [W10V]).

Black Stork (Ciconia nigra). Choni with her partner and three chicks. Year 2003. Javier Prieta.

Perhaps most interesting was documented conflicts with her neighbours. With the increase in population of vultures, it has become commonplace in Monfragüe for them to usurp nests of other species, especially black storks, but also nests of Egyptian Vultures, Bonelli's and Spanish Imperial Eagles that are found in trees. Choni began to suffer with nest occupatons by vultures in 1999. When she returned she found a vulture incubating in her nest, however, with human assistance, it was recovered and she fledged 4 chicks. In 2002 she had worse luck and this time the vultures won, leaving no other choice for Choni but to build a new nest a few meters away. Thereafter annual occupations were, even in two nests at once, although interventions by park staff eased the situation. Since 2002, Choni used the original nest five times and the new one six times. On two occasions, the first nest was used by a pair of egyptian vultures, and in 2010 there were two pairs of black storks in the nests, but the other pair did not lay eggs.

Choni nesting place between 1994 and 2011. Picture taken in 2010. With yellow circle the traditional nest, known for decades and occupied this time by another pair of black storks. With blue circle the nest "alternative" built in 2002 and occupied by Choni and her chicks. With red circle where there was a egyptian vulture nest. Above and to the right of the rock usually breed griffon vultures.

Sadly, in 2012 Choni did not return home. A sighting was reported in Monfragüe, but with no confirmation. The nest was used but both birds were unringed. Although there is no evidence that Choni has died, 21 years of life would make her the oldest known Spanish Black Stork.... and also the most famous.

Black Stork (Ciconia nigra). Choni with her three chicks. Year 2006. Javier Prieta.

This text is dedicated to GOCE, source of most of the information and experiences collected; Santi Cano for his infectious teaching and especially his passion for "Black Ladies" and José Antonio Román, Víctor Pizarro and Juan José Ferrero (Adenex ringing group), who between 1980 and 1995 ringed no less than 555 black storks in Extremadura. A task which unfortunately has not been continued, but which has helped to understand the species in Extremadura. J. A. Roman has provided data and photographs. 

Sources: 

- Ferrero, J. J. and Pizarro, V. M. 2003. The Black Stork in Extremadura. Cuadernos Poplulares No. 61. Consejería de Cultura. Junta de Extremadura. Merida.