Phenology and diurnal behavior of common shelduck Tadorna tadorna at Sebkhet Bazer (El-Eulma, Nouth-East of Hauts Plateaux, Algeria)

This work aims to study phenology and daytime budget of common shelduck Tadorna tadorna (Anatidae) for two wintering seasons (2017/2018, 2018/2019) at Sebkhet Bazer (El-Eulma) North-East of Algeria from September to March. The obtained results show that common shelduck has the status of a wintering species. It was observed presently in the site during the study period. Common shelduck numbers begin to increase from the first decade of September to reach the maximums between late December and early January, where we had recorded the peaks of abundance 840 for the first season and 930 for the second. During our monitoring, budget time results showed that feeding is the dominant activity (surface water feeding, feeding on banks, and feeding by tipping), which take a ratio of more than 68%, the second activity is swimming with 18.71%, followed by preening which holds 9.14%, sleeping activity with a ratio of 2.38%, flight take the five range with a ratio of 0.82%. Finally, courtship and agonistic behavior recorded the lowest ratio on all budget time – 0.42% and 0.38% respectively. We can conclude that Sebkhet Bazer is a diurnal grazing ground for this Anatidae species.

Adults have more male-biased sex ratios than first-winter juveniles in wintering duck populations

Background The long-term monitoring of demographic changes in waterbird populations remains limited, but such information can be valuable for conservationists and waterbird managers. Biased sex ratios can indicate differences in survival rates between sexes. In particular, differences in the sex ratios of fledged juveniles and adults can provide insight into the development of male bias among populations. Methods In this study, we used data from individual birds captured over a 57-year period to assess the extent, and temporal variability in male bias in nine populations of ducks wintering in the United Kingdom: Gadwall (Mareca strepera), Northern Mallard (Anas platyrhynchos), Northern Pintail (Anas acuta), Common Pochard (Aythya ferina), Common Shelduck (Tadorna tadorna), Northern Shoveler (Spatula clypeata), Eurasian Teal (Anas crecca), Tufted Duck (Aythya fuligula), and Eurasian Wigeon (Mareca penelope). Results Overall, eight of these populations were significantly male-biased and adults were more male-biased than first-winter juveniles for all nine populations. The increased male bias among adults is consistent with the hypothesis that factors such as higher mortality of reproductive-age females during the breeding season is a major cause of male bias in duck populations. However, such predation cannot explain the male bias detected in first-winter juveniles in four of the populations. The temporal trends in male bias differed between adults and first-winter juveniles in Northern Mallard, Northern Pintail, Common Pochard, Common Shelduck, Eurasian Teal, Tufted Duck, and Eurasian Wigeon. Over the study period we found increased male bias among adult Northern Mallard, Northern Pintail, Common Pochard, Common Shelduck, and Tufted Duck as well as both adult and first-winter juvenile Northern Shoveler. Conclusions We provide evidence that among wintering duck populations, sex ratios are typically male-biased, with adults exhibiting stronger male-biased sex ratios than first-winter juveniles. Improved monitoring of sex ratios of wintering waterbirds would help to increase our understanding of changes in waterbird demography, population structure, and observed population trends; our study shows that birds caught during ringing projects can be a valuable source of such data.

Consistent habitat preference underpins the geographically divergent autumn migration of individual Mongolian common shelducks

While many avian populations follow narrow, well-defined “migratory corridors,” individuals from other populations undertake highly divergent individual migration routes, using widely dispersed stopover sites en route between breeding and wintering areas, although the reasons for these differences are rarely investigated. We combined individual GPS-tracked migration data from Mongolian-breeding common shelduck Tadorna tadorna and remote sensing datasets, to investigate habitat selection at inland stopover sites used by these birds during dispersed autumn migration, to explain their divergent migration patterns. We used generalized linear mixed models to investigate population-level resource selection, and generalized linear models to investigate stopover-site-level resource selection. The population-level model showed that water recurrence had the strongest positive effect on determining birds’ occupancy at staging sites, while cultivated land and grassland land cover type had strongest negative effects; effects of other land cover types were negative but weaker, particularly effects of water seasonality and presence of a human footprint, which were positive but weak or non-significant, respectively. Although stopover-site-level models showed variable resource selection patterns, the variance partitioning and cross-prediction AUC scores corroborated high inter-individual consistency in habitat selection at inland stopover sites during the dispersed autumn migration. These results suggest that the geographically widespread distribution (and generally rarity) of suitable habitats explained the spatially divergent autumn migrations of Mongolian breeding common shelduck, rather than the species showing flexible autumn staging habitat occupancy.

New species on the list of species with intraspecific nest parasitism

Intraspecific nest parasitism has only recently received more attention from ornithologists. In 2001, Yom-Tov published a list of 234 species that had exhibited this behaviour. I have since found literature data on four additional species in which intraspecific nest parasitism has been observed. No such record has so far been published from Hungary. This study presents records on 25 species from Hungary and on one species from Croatia, out of which I have not found any reference for intraspecific nest parasitism in the literature for Cattle Egret (Bubulcus ibis), Eurasian Thick-knee (Burhinus oedicnemus), Black-winged Stilt (Himantopus himantopus), Collared Pratincole (Glareola pratincola), Mediterranean Gull (Larus melanocephalus), Little Tern (Sternula albifrons), Whiskered Tern (Chlidonias hybrida), Eurasian Roller (Coracias garrulus) and Eurasian Jackdaw (Corvus monedula). In addition to records from Hungary, for Black-headed Gull (Larus ridibundus) and Mediterranean Gull I also present observations from Slovakia, and for Common Shelduck (Tadorna tadorna) from Germany.

Breeding birds in the Narta Lagoon (SW Albania) in 2016

The Narta Lagoon (59 km2) is one of the largest and most important coastal wetlands for migratory and wintering waterbirds in Albania. However, the breeding bird fauna of the site is still poorly studied. The current work aims to broaden the knowledge on the list of breeding bird species, their numbers, distribution and threats in the zone (with a focus on waterbirds). Relevant information for spring migrants is also provided. The survey consisted of two field visits in April and May 2016. The entire wetland area was covered and all its habitats were visited. In total, 136 bird species were observed. The total number of breeding birds was estimated at 6,400 pairs of 85 species. The most abundant breeders were the Little Tern Sternula albifrons with 377 breeding pairs (bp), Avocet Recurvirostra avosetta with 121 bp, and Kentish Plover Charadrius alexandrinus with 96 bp. In total, 3,461 individuals belonging to 80 species were recorded as non-breeders. At the species level, the most numerous were Kentish Plover with 1,100 individuals (ind.), Marsh Sandpiper Tringa stagnatilis with 600 ind., Greater Flamingo Phoenicopterus roseus with 321 ind., Common Shelduck Tadorna tadorna with 130 ind., Spotted Redshank Tringa erythropus with 120 ind. and Dunlin Calidris alpina with 100 ind. Breeding birds assemblages within the main studied habitats (salinas, lagoon, pine forests, mixed farmland, rocky hills with olive trees, and grasslands with bushes near the coast) and threats (the most significant of which were illegal shooting, trapping and dangerous power grid) are also described. Recommendations for future bird-friendly management, appropriate conservation activities and eco-tourism in the area are made.