Resighting Black-Tailed Godwits in Doñana and Extremadura During Spring Migration
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Resighting Black-tailed godwits in Doñana and Extremadura during spring migration. January 31st to February 19th, 2021. Author: Pablo Macías Torres 1 Summary: Due to Covid-19 the RUG crew couldn't come themselves to Spain or Portugal for doing the annual resighting period during migration. This time João Belo conducted the resighting of godwits in Portugal and Pablo Macías Torres did so in Doñana and Extremadura. This document summarises the conditions of those godwits passing through Spain. Doñana From the 31st of January until the 7th of February I looked for godwits in the South of Spain. Veta la Palma hosted the largest proportion of godwits in Doñana. This time PN Marismas del Odiel almost empty, with only 6 godwits while El Rocio had a variable number of godwits, ranging from 240 to 1500 individuals. Inside Veta la Palma, Lucio del Cuquero Grande had the biggest group of godwits (8.000-12.000 individuals) while all the other fishponds had between 6.000-10.000 godwits. The godwits' behaviour was overall very calm and more than half of them were resting during daytime. The weather conditions during the fieldwork were typically winter weather including a day of heavy rains and no resightings, but also nice sunny days. Although most of the transmitter individuals were using Veta la Palma there were some distributed between smaller water pounds of restricted access inside Doñana according to the transmitter positions. Rice fields around Isla Mayor were generally ploughed and flooded, although no godwits were found here. Reading conditions were not the best since most of the godwits were resting in belly water for long periods. The numbers estimated here seemed not to increase nor decrease during my stay. 117 RUG individuals were resighted 134 times in Doñana. Extremadura From the 8th of February until the 19th of February I looked for ringed godwits in Extremadura. The weather was not bad at all with 3-4 days of rain and just two days of fog. This year the field conditions were ideal for migrating godwits. More than half of the rice fields were ploughed and flooded thanks to the abundant rain of the previous weeks. Godwit numbers were increasing over my stay as I could notice from colour resightings as well as from roosting counting. A peak of 5000-5500 godwits were using Extremadura as a stopover during their spring migration, a number that was more or less constant from February 11 until February 19. This number is slightly higher than last year. Although the godwits in Extremadura had plenty of rice fields to choose from this year, they always used the same 3-4 fields. All river plains were covered at least once, but the godwits used almost only the rice fields between Santa Amalia and Hernán Cortes and another big rice field close to Valdetorres, where more than 3000 godwits could be found every time. The roosting place was close to Vivares and they used it every day I checked. The godwits in Extremadura behaved clearly different from Doñana. Here the flocks were mainly foraging all day, with short naps in between foraging. Abdominal index profiles (API) were slightly increasing day by day over my stay and foraging behaviour was also observed inside the roosting rice field. This year only one shotgun was heard but people visiting the rice field with dogs unleash was a common thing when close to villages. Plenty of other wader species were using the rice fields including thousands of lapwings, golden plovers and dunlins. Cranes were all over the region but I did not observe any particular interaction with the godwits. This year the University of Extremadura could tag some godwits with new transmitters that were of high importance to find foraging rice fields in this huge area. Unfortunately, Amalia was not seen this year. In total 85 RUG individuals were resighted 371 times in Extremadura. Also, 276 non-RUG ringed godwits were resighted in Doñana and Extremadura. 2 3 Acknowledgements Jos Hooijmeijer, for his support provided before and during this fieldtrip. Miguel Medialdea, Quality and Environment Manager Veta la Palma (VLP). Thank you for arranging my admission to Veta la Palma and for the support provided when needed. Enrique Martínez Montes, director of PN Marismas del Odiel. Thanks for his helpful approach, allowing me to explore Marismas del Odiel freely. José Manuel Sayago, ornithologist of Marismas del Odiel Natural Park. Thanks for the excellent assistance with searching and finding the godwits in the NP. Extremadura University team: Jose Masero, Jose Mª Abad (Pipe), Jorge Sanchez, Auxiliadora Villegas, Manuel Parejo and Andrea Soriano. Thanks for the ringing sessions and the data from the transmitting godwits. 4 Introduction In 2004 the University of Groningen started a long-term demographic project on a partly colour-ringed breeding population of Black-tailed Godwits Limosa limosa (hereafter: godwits) in SW Friesland and has since then coordinated all colour marking of godwits in The Netherlands. Mainly from December onwards, Black- tailed Godwits leave their wintering areas in West-Africa to stopover areas in southern Iberia, where they join their conspecifics that have spent the entire winter there. Here they are largely confined to three areas: Doñana NP and Extremadura in Spain and the Tejo and Sado estuaries near Lisbon in Portugal (Figure 1). Since 2007 these areas are visited by experienced volunteers and researchers from the University of Groningen in search for colour-ringed godwits. In this report you will find a summary and detailed day-to-day trip report of our work in Doñana and Extremadura in winter 2021. Figure 1. Three main areas where many godwits can be observed during January-February: Extremadura (1), Donaña NP (2), Tejo- Sado (3) Resighting colour-ringed birds during this stopover period is important for several reasons: 1. If a godwit disperses outside our study area, the chance that it will be resighted elsewhere in The Netherlands is small. Without the resightings in the stopover areas, we would assume that this individual is dead and therefore underestimate annual survival, because in the breeding areas individuals have very different resighting probabilities. 2. Secondly, with enough resightings from the Iberian Peninsula we can calculate seasonal survival. In other words, we can calculate in which period of the life cycle mortalities occur more often. Or we can find out if birds that cross the Sahara have a different survival rate than birds that stay the entire winter in southern Europe. 3. By measuring the density of individuals with colour rings, we can monitor the population size of the western European part of the Black-tailed Godwit population. In 2016 we published a scientific paper about this, a true milestone summarizing 9 years of fieldwork in Iberia. Please find below the abstract. 5 30th January 2021 I arrive to Malaga airport with half an hour of delay and after picking up the renting car I drive to my temporary house in Aznalcazar, a small village at the entrance of Doñana. 31st January 2021 Cloudy 14ºC wind: 6-7m/s As expected, the first place to check is Veta la Palma. This is the place were more godwits gathered during the previous days (figure 2) and very few individuals showed movements on the East side of Guadalquivir river. At the entrance of the property, the guard check my body temperature, something is going to be a routine every time I come here. After a short talk with the guard about the landscape conditions I drive directly to Lucio del Cuquero Grande. Figure 2. Left: godwits locations on 25th of January 2021. Right: godwits locations on 28th of January 2021 My expectations are high as the last weeks have been raining abundantly. On the first look at this big water pound I realise my expectations were right and it is indeed full of water and birds! It is a great contrast with what I saw in October, when it was completely dry. Figure 3. Big resting groups in Lucio del Cuquero Grande. Left picture: North side of Lucio del Cuquero Grande. Right picture: godwits in the Southside of Lucio del Cuquero Grande only showed one leg. There is a big flock of godwits (8000 individuals) in the North of the water pound but when I check them almost all legs are covered by water. After some sightings, the group flies away and split into two. Now I am 6 in the South and have half of the group in shallow water, but only one leg per individual! Patience is sometimes the best skill in these situations and after some time I manage to get some resightings. I the afternoon I drive around other parts of the fishery and localize other big groups of godwits. Fish pounds C1 and D3 (figure 5) also host a big flock of godwits. However, because of the big godwit numbers, it was impossible to check all the fish pounds in just one day, a good signal! Today 33 RUG combinations read, not a bad start. Figure 4. B1RLYR, C2PPPW and C1GWPW with a transmitter. Figure 5. Map of Veta la Palma, Doñana Natural Park. 7 1st February 2021 The first thing to do today is to buy groceries as it is the first day that supermarkets are open since I arrived on Saturday evening (Supermarkets are closed on Sunday in small cities in Spain). On my way to Veta la Palma I check Dehesa de Abajo. It is half its capacity and only some flamingos and shovelers are using it. I drive around Isla Mayor rice fields but there are no godwits, but a short-eared owl is scared.