HERONS IN SPAIN AND EXTREMADURA. SURVEYS 2011.

SEO/BirdLife has published a monograph of the census results of breeding and wintering herons carried out in Spain in 2011 (Garrido et al. 2012). Although Extremadura is not renowned for its wetlands, rather the opposite, it ranks second after Andalusia, in terms of importance for wintering birds (32 900, 14% of Spain) and third in terms of breeding pairs (9,900 pairs, 15% of Spain, in 84 locations).

As a family, the herons are increasing and most of the studied species show increases in Spain. The night heron (Nycticorax Nycticorax) has risen from 1,300 in 1986 to 5,400 pairs in 2011. The squacco heron (Ardeolla ralloides) from 200 in 1980 to 2100 pairs in 2011. Grey heron (Ardea cinerea) from 168 in 1950 to 7,000 pairs in 2011. The purple heron (Ardea purpurea) from 2,000 in 1997-2003 to 5,400 pairs in 2011. The bittern (Botaurus stellaris) from 26 pairs in 1980 to 41 in 2011. And the great white egret (Egretta alba), which began breeding in 1997 in the Ebro Delta has gone to 53 pairs in 2011. By contrast decreases were detected in the little egret (Egretta garzetta), with a small drop in the last ten years, resulting in 2011 (9350 pairs) against 1990 figures (7,600 pairs) but lower than 2002 (10,400). The most abundant species is the only one who has suffered a significant decrease. We talked about the cattle egret (Bubulcus ibis), down from 70,000 pairs in 1989 to 40,000 in 2011. This is a species that has incresed during the twentieth century and whose population can fluctuate greatly depending on local conditions. Experts say that some species show strong expansions, then suffer a decline after which the population is consolidated and stabilized.

 

 

 

Garrido, J. R., Molina, B. y del Moral, J. C. (Eds). 2012. Las garzas en España. Población reproductora e invernante en 2010-2011 y método de censo. SEO/BirdLife. Madrid.

BREEDING HERON COUNT IN CÁCERES: PRELIMINARY RESULTS

Colony of Grey Herons (Ardea cinerea), 9 nests, and White Stork (Ciconia ciconia), 3 nests. The photograph shows the whole colony, built in a single dead Maritime Pine. The 9 Grey Heron nests break down into 5 nests with chicks of varying ages, two nests with sitting adults and two empty ones. Toril, Cáceres. 19-05-2011 (Javier Prieta). Click on the photo to see it bigger.

Now that summer has come for real, the breeding heron count in Cáceres is pretty much over. With some last-minute information still to come in, with the consequent tweaks and corrections, we can give a foretaste here of the final results, mainly to reward the participants and thank them for their sterling efforts. These thanks are fully deserved because the censusing team achieved practically complete coverage of the whole province. Once all the final results are in, especially from the province of Badajoz, which has bigger populations than Cáceres for most heron species, this blog intends to give a complete account of this final result. To see other entries on herons in Extremadura, click here.

Breeding heron count in the province of Cáceres. Preliminary results, 2011.

- Grey Heron. At least 44 colonies found with about a thousand breeding pairs between them. It is the most widespread heron species in the province, with presence in all the heron colonies found. Sharp upward trend.

- Cattle Egret. Present in only 6 colonies with a total of about 1700 pairs. Although it is still the most numerous of Extremadura's heron species, this is the lowest known figure for the species in Cáceres, with an appreciable downward trend, both in the number of colonies and the number of pairs.

- Little Egret. About 60 pairs found in 5 colonies, all mixed colonies with Cattle Egret. It has always been a scarce species in Cáceres and the present result is similar to previous counts (stable trend).

- Night Heron. One known colony (Arrocampo Reservoir) with about 20 pairs. Slight increase.

- Purple Heron. Estimated 46 pairs in the province's only breeding site (Arrocampo). Stable trend.

- Squacco Heron. At least three pairs, also in Arrocampo Reservoir. Stable trend.

- Great White Heron. After breeding for the first time in Arrocampo in 2010, at least two pairs are now nesting in the same site this year.

- There is no information on two heron species that were not targeted by the count: Little Bittern (common breeder) and Bittern (occasional breeder).

- Interesting spinoff Spoonbill information was also obtained during the heron count, with 4 breeding sites found accounting for a total of about 40 breeding pairs. These are the highest provincial figures, both in terms of colonies and breeding pairs (see 2010 figures). Upward trend.

From here we pass on our thanks to all participants and wish all blog readers a good summer.

WINTERING HERON COUNT, JANUARY 2011: EXTREMADURA RESULTS

Cattle Egret (Bubulcus ibis). Galisteo, Cáceres. Javier Prieta

As already mentioned in this blog, the National Count of Wintering Herons was held last January. As usual the overall result will be published by SEO/BirdLife. For the moment, however, we can give you a foretaste of the Extremadura results.

The chosen methodology was to count birds in communal roosts. The main date was the weekend 15-16 January, although some counts were held a few days later. No information was obtained for the abundant but non-roost-forming Grey Heron. The same goes for the scarcer heron species (Squacco Heron and Bittern) or the ones that are nocturnal or difficult to detect (Little Bittern).

RESULTS BY SPECIES

Cattle Egret (Bubulcus ibis). 30,917 birds (22,315 in Badajoz and 8602 in Cáceres) in 38 roosts (23 in Badajoz and 15 in Cáceres). Eleven roosts held over one thousand birds, the standout ones being Azud de Badajoz (6103), River Zújar in Villanueva de la Serena (4200), Valuengo Reservoir (2700), Madrigalejo (2400) and River Guadiana in Montijo (2000). The attached map, plotting the location of the roosts, brings out the obvious importance of the River Guadiana and its surrounding meadows, which account for the lion's share of the regional population.

Little Egret (Egretta garzetta). 1273 birds (823 in Badajoz and 450 in Cáceres) in 38 roosts (20 in Badajoz and 18 in Cáceres). Seven roosts held over 50 birds, the biggest being Valuengo Reservoir (230), Madrigalejo (125) and River Guadiana in Montijo (100).

Great White Egret (Egretta alba). 67 birds in 18 roosts (31 in Badajoz and 36 in Cáceres). The biggest roosts were on the River Tiétar in Malpartida de Plasencia (15), Arrocampo Reservoir (9), Valdecaballeros Reservoir(7) and River Zújar in Villanueva de la Serena (6).

Night Heron (Nycticorax nycticorax). 52 birds in 5 roosts, all on the River Guadiana in the province of Badajoz. The most important roosts were Montijo Reservoir in Mérida (29) and Azud de Badajoz (10).

TREND

There's nothing specific to go on in terms of wintering herons in Extremadura. In January 1992 and 1993, however, two Iberian counts were conducted, giving the results by catchment areas (Fernández-Cruz and Farinha, 1992; Sarasa et al., 1993), but without breaking down the figures by regions or provinces. Working from the maps shown in the 1992 count, we estimate about 53,000 Cattle Egrets and 1500 Little Egrets in Extremadura. The 1993 figures were lower but the estimate is rougher because there is no map to go on; maybe the figures were about 42,000 and 700 respectively.

The number of Cattle Egret roosts has fallen from 64 in 1992 to 37 in 2011, a 40% drop. The fall in the number of birds was similar, about 35% on the mean figure for 1992-1993. This decline is much more notable in the Extremadura part of the Tagus catchment area (-60%) than in that of the River Guadiana (-20%). This figures should not really be taken in isolation, however, since the wintering population of the southwest Iberian Peninsula, including Portugal and Morocco, tends to behave as a metapopulation acting as a whole unit. Due consideration also has to be given to the possible differences in the censusing effort in the two years and the big swings from year to year and even month to month. Thus, in January 2011 5200 Cattle Egrets were counted in the Cáceres catchment area of the Tagus; only a few months earlier, in October 2010, two roosts alone pooled over 3000, this figure falling to 700 in January 2011 and then soaring to no less than 6000 in November 2007. Some districts with heron roosts in autumn were also empty by the following January. Although the information on previous years is bitty, it might well be a habitual practice for the Cáceres catchment area of the Tagus to have a bigger Cattle Egret population in autumn than in winter. What has been clearly recorded is a marked fall in some roosts associated with landfill sites; witness the case of the roost near the capital city of Cáceres capital, which was Spain's biggest in 1992, with nearly 8000 birds; by 2011 the number had dropped to one thousand.

As for the Little Egret, it is difficult to establish a clear trend due to the big difference in the estimated figures for January 1992 (1500 birds) and January 1993 (700). The number of roosts was almost the same 1992 (37) and in 2011 (38) and the number of birds in 2011 (1273) is 15% up on the mean figure for 1992-1993 (1100). Unlike the Cattle Egret, the Little Egret's wintering population has risen sharply in the Tagus catchment area since 1992, with a slight fall in the Guadiana. Another factor that has to be taken into consideration here is the possibility of confusion in some counts with the abundant Cattle Egrets; some small Little Egret roosts might even go totally unnoticed.

According to the annual January Wildfowl Count the trends in Spain (Molina, 2011) for the four heron species are:
- Cattle Egret: reduction in the 1991-2009 period and especially in 2000-2009
- Little Egret: sharp increase from 1991 to 2009, flattening out in 2000-2009
- Grey Heron: increase in the 1991-2009 period
- Great White Heron: sharp increase in the 1991-2009 period.

Lastly, neither in 1992 nor in 1993 were Night Herons or Great White Egrets detected in Extremadura; they would therefore seem to be new winter visitors to the region.

ACKNOWLEDGEMENTS

The National Wintering Heron Count is a project of SEO/BirdLifes' Bird Monitoring Area, run by Juan Carlos del Moral. In Extremadura the survey was coordinated by José María Traverso (Badajoz) and Javier Prieta (Cáceres). The fieldwork involved the collaboration of the 59 following collaborators: Pablo Caballero Javier Prieta, César Clemente, Javier Mahillo, Sergio Mayordomo, Eva Palacios, Jesús Montero, Manuel García del Rey, Emilio Pérez-Balsalobre, Javier Briz, Vicente Risco, Laura Alicia Rodríguez, Carmelo López, Helios Dalmau, Colin Jewitt, Marcelino Cardalliaguet, F. Javier Caballero, José Luis Caballero, Martin Kelsey, Jesús Solana, Juan Carlos Paniagua, Emilio Costillo, Casimiro Corbacho, Fernando Yuste, José Gordillo, Pedro Schreur, Godfried Schreur, Jesús Morena, José Antonio Fimia, Maria Jesús Tarín, Alfredo Mirat, Jesus Rojas, Carmen Galán, Álvaro Martín, Chema Traverso, Álvaro Sánchez Arribas, Antonio Núñez, Diego González Romero, Raquel Rangel Vanessa de Alba, Toribio Álvarez, Celsa Agudo, José María Abad, Patricia Gordon, María Jesús García-Baquero, Manuel Parejo, Raquel García Hierro, J. Elías Rodríguez, Juan Luis Soriano, María Luisa Villoslada, Juan Antonio Barquero, Elvira del Viejo, Juan Villalobos, Antonia Cangas, José Ángel Salas, Gerardo Pizarro, Emilio Jiménez, Agustín Sanabria.

Sources
- Fernández-Cruz, M. & Farinha, J. C. 1992. Primer censo de ardeidas invernantes in la península Ibérica and Baleares (1991-92). Airo 3:41-54. [download PDF]
- Sarasa, C. G., Bartolomé, J., Fernández-Cruz, M. & Farinha, J. C. 1993. Segundo censo de ardeidas invernantes in la penínsulas Ibérica and Baleares (1992-93). Airo 4:41-50. [download PDF]
- Molina, 2011. Censo nacional de aves acuáticas invernantes, Enero 2009. In, Escandell, V.; Palomino, D.; Molina, B.; Leal, A.; Remacha, C.; Bermejo, A.; De la Puente, J. and del Moral, J. C. (Eds.). Programas de seguimiento de SEO/BirdLife in 2009-2010. SEO/BirdLife. Madrid. [download PDF]