Teal Marmaronetta Angustirostris Research Articles

Blind shots: non‐natural mortality counteracts conservation efforts of a threatened waterbird

AbstractWaterbirds are particularly affected by the high hunting pressure they face in many regions, which in some cases is compromising conservation actions for threatened species. The marbled teal Marmaronetta angustirostris is one of the most endangered waterbirds in Europe. In order to restore its population, several conservation actions have recently been undertaken, including a population reinforcement programme in Spain using captive‐bred birds. With the aim of assessing the success of the reinforcement programme to establish a long‐term self‐sustaining population, we identified mortality causes of marbled teal, evaluated the survival of individual birds of the reinforcement programme and estimated the viability of the population under different management scenarios. We used data from wild and captive‐bred individuals tracked by GPS since 2018 (n = 42) and from a mark–recapture programme initiated in 2015 (n = 297). We recovered 15 dead birds or transmitters: 20% died of natural causes, 60% of non‐natural causes (including all anthropic causes) and 20% of unknown causes. Furthermore, the GPS tags of 24 birds unexpectedly stopped transmitting without any indication of malfunction, and for 66.7% of these disappeared birds, the cessation was suspected to be caused by illegal shooting. Survival during the hunting season was higher for males (31.3%) than for females (12.5%), and for the wild (50%) than for the captive‐bred birds (9.4%), probably due to differences in migration patterns to North Africa. Population viability models revealed that maintaining the breeding population at the current mortality rates is only possible with a permanent release programme of captive‐bred individuals, and that in order to establish a self‐sustaining population, non‐natural mortality would have to be reduced by at least 40%. We recommend management measures to reduce marbled teal mortality, such as limiting legal hunting to hours with clear visibility, prosecuting illegal shootings, controlling exotic predators and improving water management to reduce disease outbreaks. Some improvements can be implemented in captive‐breeding programmes, such as earlier release times and incorporating anti‐predator training.

Marbled Teal Marmaronetta angustirostris breeding in Wadi Djedi at Ziban region, Algerian Sahara

This note reports the breeding of Marbled Teal Marmaronetta angustirostris at Wadi Djedi wetland at Ziban oasis, in the northeastern Algerian Sahara). On 14 May 2019, two females and their ducklings were observed. This breeding provides evidence that Marbled Teal may breed elsewhere in the region and provides the first information concerning the breeding strategy of this species in Algeria, especially in the northeastern Algerian Sahara Urgent measures and regular surveys are needed to protect this vulnerable species and their preferred habitats.

Distribution of breeding waterbirds in relation to wetland characteristics in the Oued Righ valley in the Algerian Sahara

Abstract In the framework of this study 14 breeding species were identified in the wetland complex of the Oued Righ valley in the Algerian Sahara. Six species of breeding Anatidae were reported, two of which are classified as vulnerable and threatened, namely, the ferruginous duck Aythya nyroca and the marbled teal Marmaronetta angustirostris. For shorebirds, we noted reproduction of the pied avocet Recurvirostra avosetta, the black-winged stilt Himantopus Himantopus, and the Kentish plover Charadrius alexandrinus in most of the wetlands studied. We report for the first time nesting of the slender-billed gull Chroicocephalus genei at Chott Merouane with 72 pairs recorded during the breeding season 2018. This colony was associated with the larger colony of greater flamingo Phoenicopterus roseus composed of 640 pairs. Principal component analysis (PCA), gathering 69.74% of the information, showed a significant correlation between the distribution of different bird species and the main environmental factors, that is, vegetation, water surface area, water depth, and salinity, and a strong correlation between the species of Annatidae and Rallidae, which are associated with less-saline environments rich in vegetation and deep water, with the exception of shelducks, which prefer large surface areas with less-dense vegetation and more holomorphic water. For the shorebirds such as R. avosetta and H. himantopus, there was a clear preference for large wetlands with shallow water and relatively high salinity. A remarkable correlation was also noted for P. roseus, where a strong distribution of breeding populations was observed in areas with the highest salinity levels and a vast surface area.

Factors Predicting Ramsar Site Occupancy by Threatened Waterfowl: The Case of the Marbled TealMarmaronetta angustirostrisand Ferruginous DuckAythya nyrocain Morocco

Summary. Since 2005, Morocco has designated many Ramsar wetlands, yet little is known about factors determining their occupation by waterbird communities. In this study, we assessed the relationship between the occupation of Moroccan Ramsar wetlands during the breeding season by two globally threatened waterbirds, the marbled teal Marmaronetta angustirostris and the ferruginous duck Aythya nyroca, and geographical, topographical and macrohabitat factors. Habitat-based statistical models showed that the presence of these two threatened waterfowl species at Moroccan wetlands was positively correlated with the number of emergent vegetation species, and negatively correlated with altitude and the distance to the nearest coastline. These results highlighted previous findings regarding the significant and positive relationship between the number of plant taxa and the number of threatened waterbird species at Moroccan wetlands. Further investigations should be conducted at regional (Maghreb region) and internati...

Marbled Teal Marmaronetta angustirostris and Cape Teal Anas capensis on the Ounianga Lakes, northern Chad

Marbled Teal Marmaronetta angustirostris and Cape Teal Anas capensis on the Ounianga Lakes, northern Chad

The diet of the Marbled Teal Marmaronetta angustirostris in southern Alicante, eastern Spain

We present a study of the diet of the globally threatened Marbled Teal Marmaronetta angustirostris in the southern Alicante wetlands, the most important site for the European population. We analysed the gut contents of 64 fully-grown teal collected between 16 June and 24 November from 1992 to 2000, and 31 ducklings (29 of the newly hatched age class Ia) collected between 18 May and 16 July from 1994 to 1998. The ducklings died following rescue from a concrete irrigation channel, and all but 4 fully-grown teal died in various mortalities. We also analysed 20 faecal samples collected from fully-grown teal in July-August in 1999 and 2000, plus faecal samples collected from five broods after their rescue from the channel. Seeds (72% by aggregate percent of gullet volume), supplemented by invertebrates (21%) dominated gut samples from fully-grown teal. The most important food item was Scirpus litoralis seeds (43% by aggregate percent of gullet volume) consumed mainly when floating on the water surface. The importance of invertebrates was probably underestimated owing to the poor quality of gut samples. Chironomid larvae and pupae, Corixidae and their eggs, ants, ostracods and amphipods were the most abundant invertebrates by volume. Green plant material (probably Potamogeton pectinatus) was abundant in July faeces. There were no clear seasonal trends in diet, perhaps because of the poor quality of most gut samples and variation between years in the seasonal patterns of abundance of different seeds and invertebrates. Ducklings fed mainly on invertebrates, especially chironomid adults and pupae, Coleoptera, Corixidae and ants. They consumed more green plant matter than seeds.

Spatial and temporal variation in the diet of Marbled Teal Marmaronetta angustirostris in the western Mediterranean

CapsuleThis globally threatened species is less dependent on invertebrates and more dependent on seeds than other ducks. Aims To assess seasonal variation in Marbled Teal diet at two of the most important wetlands for the west Mediterranean population. Methods Faecal samples from El Hotba, Morocco (19 in October, 28 in May) and Veta la Palma, Doñana (19 in August, five from July broods) were analysed. Gut contents of six birds from Veta la Palma (September–October) were analysed. Results At El Hotba, small seeds (especially Ruppia) and green plant material (especially charophytes) were the dominant faecal components in May and October. The proportion of invertebrates did not change, but more Corixidae and less Chironomidae were consumed in May. At Veta la Palma, Ruppia seeds were dominant in August, but Ephydridae, Chironomidae, Coleoptera and other insects were dominant in faeces from July broods. Significantly fewer Coleoptera but more Foraminifera were recorded in August. The overall proportion of invertebrates at El Hotba in May and October was higher than at Veta la Palma in August, but lower than in July broods. Corixidae were dominant in May, Ephydridae in July broods, unidentified insects, Ostracoda and Foraminifera in August and Coleoptera in October. Gut contents from Veta la Palma confirmed the dominance of Ruppia seeds in the post-breeding diet. Conclusion Marbled Teal differs in its ecology from the better-known north-temperate ducks. With the exception of ducklings, they are less dependent on invertebrates and rely on small seeds more than north-temperate ducks.

Waterbirds in coastal wetlands along the Persian Gulf coast of Iran, January–February 2000

In January and February 2000, about 20 wetland sites were visited to count waterbirds and pay special attention to the presence of Slender-billed Curlews Numenius tenuirostris, a Globally Threatened species. At least 1,200 Eurasian Curlews N. arquata and 240 Whimbrels N. phaeopus were checked individually, but no Slender-billed Curlews were observed. More than 53,000 waterbirds of 82 species were counted during the survey, including Globally Threatened Species like Dalmatian Pelican Pelecanus crispus, Marbled Teal Marmaronetta angustirostris, Ferrugineous Duck Aythya nyroca, White-tailed Eagle Halaeetus albicilla, Greater Spotted Eagle Aquila clanga, and Imperial Eagle Aquila heliaca. Only a small part of the wetlands along the Iranian Gulf coast were counted and a total of over 240,000 waders were estimated to winter in the surveyed wetlands. Our survey suggests that the total Iranian Gulf coast is very important for waterbirds and in particular for waders and Dalmatian Pelican. Apparently suitable habitat for Slender-billed Curlews, including irrigated wheat fields, extensive salt marshes and marshland close to intertidal mudflats, was found in the Hilleh Protected Area (42,600 ha) and Monde Protected Area (46,700 ha), as well as much of the surrounding area up to Bushehr and Monde River Delta.

The scaling and selection of sexually dimorphic characters: an example using the Marbled Teal

Current theory and empirical evidence suggests that, if a character is sexually dimorphic as a result of sexual selection, it should be positively allometric (i.e. relatively larger in larger individuals), whereas if the dimorphism is the result of natural selection (e.g. niche divergence), it should be isometric. I show how this can be used to study the selective forces responsible for dimorphic morphological characters, using the monochromatic Marbled Teal Marmaronetta angustirostris as an example. In absolute terms, first‐year male teals have a higher body mass, wing length, head length and bill length than females. In relative terms (controlling for body size), males still have longer wings, heads and bills. The scaling in Marbled Teal suggests that bill and head dimorphisms are due to sexual selection, whereas wing dimorphism is due to natural selection. Tail length is sexually monomorphic but positively allometric, possibly because of a display function. Such scaling studies are easy to carry out, and provide a useful complement to direct investigation of the influence of variation in the size of dimorphic characters on mating success, foraging efficiency etc.

Clutch size, brood size and brood emergence in the Marbled Teal Marmaronetta angustirostris in the Marismas del Guadalquivir, southwestern Spain

The first detailed study of the breeding biology of the globally threatened Marbled Teal Marmaronetta angustirostris is presented, using data from the Marismas del Guadalquivir in southwestern Spain. Complete clutches, with 9–20 eggs, were recorded from 28 April to 27 July. Excluding clutches of over 14 eggs (likely to be intraspecifically parasitized), the mean clutch size was 11.8, larger than that reported for almost all other Anatidae species. Broods hatched from May to early August (later than sympatric duck species), with a peak in mid‐late June and significant annual variation in date. Brood sizes were exceptionally high, declining from a mean of 10.9 in the first week of age to 8.5 when fully feathered (at 42 days or more). Duckling mortality was concentrated in the first 2 weeks after hatching. Nine percent of broods had 15–23 ducklings, largely as a result of nest parasitism. Brood size decreased strongly with hatching date and varied significantly between years. Data from across the species' range showed that breeding occurs later at more northerly latitudes. A recent decline in the Marbled Teal in the Marismas is linked with its late breeding season. Anthropogenic changes have reduced the duration of flooding in the natural marshes of Donana National Park, which now dry out by August, before this species has completed breeding

Habitat selection by the Marbled Teal Marmaronetta angustirostris, Ferrugineous Duck Aythya nyroca and other ducks in the Göksu Delta, Turkey in summer

La sélection de l’habitat diurne a été étudiée du 10 juillet au 6 août 1995 dans le delta de Göksu, Turquie, pour la Sarcelle marbrée Marmaronetta angustirostris, le Fuligule nyroca Aythya nyroca, la Sarcelle d’été Anas querquedula et le Canard colvert Anas platyrhynchos. Il s’agit de la première étude détaillée de ce type pour les espèces globalement menacées que sont la Sarcelle marbrée et le Fuligule nyroca. Toutes les espèces étaient concentrées sur des lacs riches en denses formations végétales émergentes ou sub-émergentes, évitant les lacs ouverts et salés ainsi que les canaux étroits et isolés. La Sarcelle d’été et le Colvert étaient concentrés dans la «zone émergente mixte» du lac Akgöl, saumâtre, composée d’un mélange de Phragmites australis, Typha et Scirpus littoralis. La Sarcelle marbrée se localisait essentiellement dans une zone plus centrale, pourvue de formations monospécifiques de S. littoralis, le Nyroca étant intermédiaire. Le Colvert et en particulier la Sarcelle marbrée montraient une certaine préférence pour les petits étangs autour du lac, moins profonds et qui permettaient probablement une meilleure alimentation. Les nichées de Sarcelle marbrée étaient très concentrées au débouché d’un canal de drainage dans le lac, ce qui constituait un refuge diurne sûr, adjacent à un gagnage nocturne possible. Sur le lac Akgöl, la Sarcelle marbrée utilisait des microhabitats dominés par S. littoralis, la Sarcelle d’été était davantage associée aux Typha tandis que le Colvert et le Nyroca étaient autant associés aux Typha qu’aux Phragmites. Le Colvert restait au plus près de la végétation émergente, la Sarcelle d’été utilisant surtout les microhabitats ouverts loin des émergents. Le Nyroca utilisait des zones au plus loin de la rive du lac. Toutes les espèces sélectionnaient fortement les denses formations de Potamoge-ton pectinatus, en raison de leur importance en tant qu’ habitat d’alimentation. Une gestion prudente est requise pour maintenir la forte valeur d’Akgöl pour les oiseaux d’eau. Le rétablissement des populations de Sarcelle marbrée et de Nyroca dans d’autres parties de la region méditerranéenne nécessite la conservation et la restauration de lieux de reproduction à végétation luxuriante.

Brood attendance and brood care in the Marbled Teal,Marmaronetta angustirostris

Brood attendance by adults in the globally threatened Marbled TealMarmaronetta angustirostris was studied in the field in Spain and Turkey. In seven broods, only one adult (thought to be the female) was seen attending. Two adults were in attendance for 10 broods, amongst which all age classes were represented. These were confirmed to be a male and a female in four broods observed at close range. When these four broods were disturbed, the female led the ducklings into emergent cover whilst the male remained close to the human observer, flying around or past him repeatedly and giving conspicuous alarm calls. This may be a form of paternal care (guarding or warning behaviour) as it was never observed in males not accompanying broods. Paternal brood attendance and care has not been reported in other Aythyini (pochards), but Marbled Teal have monochromatic plumage and other features associated with paternal brood attendance and care in Anatini (dabbling ducks).

National censuses of the Marbled Teal Marmaronetta angustirostris in Spain

National censuses of the globally threatened Marbled Teal were organized in Spain in 1994 and 1995 during the prebreeding, breeding and post-breeding periods. This is the first detailed study of the status and distribution of the species in any country. The censuses revealed a drastic decrease in Marbled Teal numbers in the Guadalquivir marshes in Andalucía (their former stronghold) but numbers in the other main subpopulation in Valencia region are not currently in decline. The average national count (excluding pulli) was 55 in 1994 and 50 in 1995. In 1994, 75% of birds and 86% of broods were recorded in Valencia region, with 23% of birds and 14% of broods in Andalucía and 3% of birds in Murcia. In 1995, 91% of birds and 95% of broods were recorded in Valencia region, with 9% of birds and 8% of broods in Andalucía. The censuses provide evidence of movements from the Guadalquivir marshes to Valencia during the breeding season, in response to severe drought in the former area.

L’évolution récente de l’avifaune du Nord-Est marocain : pertes et gains depuis 35 ans

The author studied the avifauna of north-eastern Morocco from 1953 to 1959 as a resident naturalist, and visited the area occasionally afterwards. A more recent visit enables him to review the drastic changes, both negative and positive, which took place in the past 35 years, due to demographic pressure and agricultural development. On the plateau steppe, the numerous birds of prey and corvids which used to nest on the scattered betoum trees Pistacia atlantica have now disappeared, the « dayas » being presently used for cultivation. On the other hand, the large raptors, social corvids, and bald ibises Geronticus eremita, formerly breeding on the cliffs of the Debdou-Tlemcen ridge, also disappeared due to direct human persecution. Conversely, the small species of larks, chats, finches, and warblers are now as numerous as before. On the contrary, the damming of the River Moulouya and the irrigation of 30,000 ha of the coastal plain, have drastically altered the course of the river and the shape of the delta, creating oxbow lakes and increasing significantly the size of the original wetlands. These artificial wetlands now attract large populations of water birds, 18 species of which were found breeding versus 4 in 1959. Among them, the Marbled teal Marmaronetta angustirostris and the Purple gallinule Porphyrio porphyrio are now firmly established. Palearctic migrants were also observed in large numbers in this area. The lower Moulouya wetlands should now be protected as soon as possible.