The Dutch Constant Effort Site (CES) programme has been operating since 1994 and is especially designed for the analysis of demographic parameters. Currently, it works with 40 active mist-netting sites and has a database with more than 250,000 records at its disposal. Here, we ask whether the effort invested in the programme is appropriate to detect temporal trends of productivity of passerine bird populations across The Netherlands. We specifically ask if less effort would produce the same results or if the number of CESs should be augmented. To evaluate these questions we used a resampling approach in which we decreased sample size in steps of five and iterated resampling 1000 times for each step, thus simulating CES programmes in which fewer sites were operated. For the twenty most abundant species and for each sample size, linear regressions of the productivity index (a logistic generalized linear model of the proportion of captured juvenile birds) on year were compared with the regression obtained using the complete records. The proportion of samples that yielded significant positive or negative slopes was determined, as well. For the majority of species without significant temporal trends (18), the proportions of significant slopes at smaller sample sizes were lower than 20%, indicating a moderate risk of committing Type I errors (detecting a negative or positive trend although productivity did not change over time). For the Garden Warbler Sylvia borin, which showed a significant positive productivity trend, the probability of committing Type II errors (not detecting existing trends) increased rapidly with decreasing sample size. We conclude that the Dutch CES programme works with a sufficient number of sites to detect reliable temporal trends for most of the more abundant passerine species. However, increasing the number of sites would allow for a more secure determination of productivity trends for those species that currently show ambiguous results (Reed Warbler Acrocephalus scirpaceus, Willow Warbler Phylloscopus trochilus, Willow Tit Parus montanus).

Counts of migrating raptors at Batumi, Georgia, revealed the eastern Black Sea coast to form one of the most important bottlenecks for raptor migration during autumn in the Eurasian-African migration system. Totals for 10 species (European Honey-buzzard Pernis apivorus, Steppe Buzzard Buteo buteo vulpinus, Black Kite Milvus migrans, Eurasian Sparrowhawk Accipiter nisus, Levant Sparrowhawk Accipiter brevipes, Montagu's Harrier Circus pygargus, Pallid Harrier Circus macrourus, Lesser Spotted Eagle Aquila pomarina, Greater Spotted Eagle Aquila clanga, Booted Eagle Aquila pennata) exceeded 1% of their estimated world population. We compare the observed abundance of each species to estimates of the presumed source populations in European Russia. Counts of most species involved only a limited subset of these source populations, except for European Honey-buzzard and Lesser Spotted Eagle, which were more numerous than predicted. This could be due to inaccurate population estimates or because birds from NE Europe or W Asia are also using this migration route.

On the floodplain meadows of the Pripyat River in southern Belarus, Ruffs Philomachus pugnax form concentrations of up to 30,000 individuals during spring migration. The Ruffs replenish their energy reserves before continuing their northwards migration. Over eight spring seasons, between late March and middle May 2001–2008, we measured the body mass increase in a sample of 2839 adult and 342 immature males, and 2058 adult and 136 immature females caught in the middle Pripyat near Turov. Body mass increased in two phases in the spring season, rising slowly in the first and faster in the second phase; the breakpoint date between the two phases differed between the sexes (24 April and 3 May, respectively) and showed less variation in females than in males. Adult males gained an average of 1.1 g/day in the first phase and later 2.4 g/day. Immature males gained 0.39 g/day in the earlier phase and 1.7 g/day later. Adult females gained on average 0.56 g/day in the early phase and 1.22 g/day later. In immature females the rate of body mass gain was not significant. The rate of body mass increase varied among years. The water level had a negative impact on the body mass increase in females, but not in males. Presumably, males are less affected by the water level as they have much longer legs and are able to forage in deeper water. According to the estimated flight ranges, both sexes were able to reach at least the breeding grounds in the western part of Siberia in one nonstop flight, except in years with higher water levels. The middle Pripyat is probably the last stopover site before their breeding grounds for at least a portion of these birds.

In migrants that occupy and defend territories during migration, social status can determine access to preferred resources and alter stopover behaviour. The potential variation in stopover behaviour between dominant and subordinate individuals of the Northern Wheatear Oenanthe oenanthe, a territorial migrant bird species, was examined at an offshore stopover area on the island of Helgoland during the spring of 2009. Overall, territories were occupied and defended by dominant birds (identified as those that won ≥50% of the conspecific aggressive encounters). Dominant birds also initiated most conspecific aggression. Unable to settle and defend a territory, subordinates tended to be vagrant and stopped over for shorter periods of time. This is likely due to the fact that subordinates were continuously displaced by dominants, and therefore had less access to food. Subordinates also tended to forage at lower rates. Northern Wheatears were primarily found in zones with a higher number of shelters, supporting the idea that avoidance of predation plays a role in site selection.

The advantages and disadvantages of breeding in nestboxes are well known, whilst the merits of roosting in nestboxes during the non-breeding season remain poorly understood. Here I review the advantages and disadvantages of using nestboxes as roosting sites during the non-breeding season. The main advantage of nestboxes is that they increase the number of cavities available for roosting and birds gain considerable thermal benefits and energy savings, when compared to congeners roosting outside of cavities. However, the main disadvantage is that roosting birds are widely targeted by detrimental ectoparasites, and birds actively avoid nestboxes where ectoparasites are abundant. Meanwhile, there is insufficient evidence to make any firm conclusions as to whether roosting in nestboxes increases or decreases predation risk and this is an area, which warrants further research. Consequently, there is a great deal of variation in the quality of individual nestboxes as roosting sites, and interspecific competition results in larger and more dominant species roosting in preferred nestboxes. In summary, this review emphasises the importance of nestboxes to roosting birds during the non-breeding season.

The role of olfaction for predation risk assessment remains barely explored in birds, although predator chemical cues could be useful in predator detection under low visibility conditions for many bird species. We examine whether Great Tits Parus major are able to use the odour of mustelids to assess predation risk when selecting cavities for roosting. We analysed whether the response to predator chemical cues is innate and assessed whether the antipredatory response is associated with exploratory behaviour, a proxy for the personality of birds. In a choice experiment in aviaries, we offered naïve adult Great Tits of known personality two nest-boxes, one control and one experimental. The experimental nest-box had the odour of a mustelid predator or a strong new odour without biological significance, the control nest-box contained no odour. When one of the cavities contained the odour of a predator, birds avoided the use of either of the two offered nest-boxes, whereas there was no avoidance of boxes when one of the nest-boxes contained a control odour. There was no relationship with exploratory behaviour. We show that the ability to use the chemical cues of predators is innate in birds, but individual differences in the response to predator chemical cues cannot be explained by the personality of the bird.

Protecting breeding sites should not be the only conservation measure for seabirds that exhibit delayed maturity and spend extended periods of time in their non-breeding areas. We investigated age at first breeding and immature survival of Damara Terns Sterna balaenarum which breed in southern Africa and migrate c. 4000 km to their non-breeding grounds in West Africa. Using multi-state capture—mark—recapture models adult annual survival was estimated to be 0.87 (95% confidence interval: 0.73–0.94). Mean annual immature survival of Damara Terns from nest stage to breeding was estimated to be 0.59 (95% confidence interval: 0.48–0.68). Immature survival contained an element of pre-fledging mortality since most individuals were ringed before fledging. Furthermore, our estimate could be biased low due to permanent emigration from the study area. The age at first breeding was three years (probability of 0.27), and all terns were breeding at four years. This is comparable to other plunge-diving migratory terns which have extended periods of post-fledging dependence. In the light of this we suggest that consideration be given regarding the protection of the species in its non-breeding countries in addition to the protection of current breeding sites.

I examined sexual size dimorphism (SSD) and assortative mating and estimated a discriminant function for predicting sex in the Whiskered Tern Chlidonias hybrida, a medium-sized marsh tern. I measured and molecularly sexed 241 breeding adults captured in southern Poland from 2005 to 2010. Males were significantly larger than females in all six measurements: total head length, bill length, bill depth at gonys, tarsus length, wing length and body mass. The largest dimorphism index (DI) was found in head and bill measurements and body mass. Within pairs, the total head length, bill length and bill depth were positively correlated. Two discriminant functions, one based on the length and depth of the bill and the second including only total head length, showed the same high sex classification success of 95%. DI in Whiskered Terns was greater than in other terns probably due to stronger sex specialization in foraging niche.

Understanding the factors that influence territorial behaviour is essential for determining whether fragmented habitats are able to support the spatial ecological conditions that maintain cooperative breeding systems of threatened bird species. Here, we examine territorial behaviour of the cooperative breeding Buff-throated Partridge Tetraophasis szechenyii in patchy tree-line habitats of the Pamuling Mountains in western China. This population has been habituated to humans through supplementary feeding by Tibetan Monks. We studied 18 groups during three consecutive breeding seasons and two non-breeding seasons from March 2007 through July 2009, using direct tracking of colourmarked individuals. Territories were occupied by stable family groups, and were centred on the interface of two or more different tree-line habitats. Groups occupied the same close area near the nest from one year to the next. However, territory sizes, estimated using radio-telemetry, were smaller compared to those of other non-cooperative breeding montane Galliformes. Both territory size and overlap were greater during the non-breeding season. Group size did not influence territory size, in either the breeding or non-breeding season. Territorial behaviour was influenced by supplementary food given at two offering sites during both seasons, in proximity to both nesting and roost sites. Further research should focus on examining the interactions between supplementary feeding and family group composition, with direct comparisons of data from non-supplementary fed partridge populations outside of Buddhist Sacred Sites.

The diet of Great Cormorants Phalacrocorax carbo sinensis at Lake Dümmer, a shallow eutrophic lake of 1240 ha in Lower Saxony (Germany) was analysed by collecting 562 regurgitated pellets over a period of one year. Pellets contained structures of 10,645 fishes belonging to 15 species. Substantial differences were found in frequency, composition and size of prey fish species. Pikeperch, Ruffe, Roach and Perch accounted for the largest seasonal differences in the diet. During late autumn and winter the diet was dominated by small-sized cyprinids and Ruffe. In spring Great Cormorants primarily foraged on larger-sized cyprinids. Young-of-the-year percids, dominated by Pikeperch, were the primary prey during summer. We estimated that at least 32.6 tons (26.3 kg/ha) of total fish biomass was removed by Cormorants, of which one third (10.8 tons) consisted of Pikeperch. 81% of the Pikeperch biomass was removed in August—September, indicating that the Great Cormorant is an important predator of juvenile Pikeperch at Lake Dümmer. Our findings highlight the need of extensive diet analyses in all seasons to obtain a comprehensive picture of the impact of Cormorant predation on fish stocks. Snapshots of the diet sampled over short-time periods may be misleading and inadequate for local management.

We used GPS satellite tracking data and field measurements of vegetation to investigate the effect of food resources, distance to roosts, and the location of refuges on the distribution of Barnacle Geese Branta leucopsis in the northern part of The Netherlands. To deal with spatial dependence among the data, a spatial lag model was used. A significant quadratic effect was found between sward height and goose distribution, indicating that geese prefer patches with intermediate sward heights. The manipulation of sward height can therefore be used to attract geese to refuges and thus reduce goose grazing in agricultural land. No relationship was found between grass nitrogen content and grazing intensity, indicating that geese do not distinguish between areas based on nitrogen content. A higher grazing intensity was observed in areas located within 2 km from roosts. The eight tracked geese spent 80% of their foraging time in refuges, demonstrating the importance of the refuge system.

Nest predation was studied in a population of Tawny Owls Strix aluco in the Duna-Ipoly National Park, Hungary during the period 1992–2009, and related to the choice of nesting sites at different altitudes, the breeding experience of males, and weather conditions. The use of nesting sites at high elevations reduced the risk of nest predation in comparison to lower elevations, where breeding territories occur at a higher density. Also, the risk of nest predation decreased as the local breeding experience of males increased. Adverse weather conditions, i.e. long-lasting snow cover, increasing breeding density, and later laying dates enhanced the probability of breeding failure by nest predation. Broods were depredated in the nestling period rather than during incubation.

This note corrects a statement made in an earlier note on flock-fishing Great Crested Grebes Podiceps cristatus at the South Swedish Lake Krankesjön, namely that the flocks presumably consisted mainly of non-breeders. This has been proved wrong. The majority come from a loose colony and consist of birds during incubation recesses. Flock-fishing started around 1 May in 2008, 2009 and 2011, but not until the beginning of June in 2010. The reason for the late start in 2010 is unclear. Flocks formed soon after sunrise and dissolved at various times during the day. Only once was a fishing flock seen in early evening.

This paper provides data on the breeding biology and social system of the Black Redstart Phoenicurus ochruros at a Tibetan site (4300 m elevation). Egg-laying occurred between early May and early July during which pairs bred once (10 out of 12 marked pairs) or twice (2). Clutch size varied between 4 and 5 eggs (4.56 ± 0.51 SE), but a seven-egg clutch was recorded. Incubation by the female lasted 12–14 d (13.0 ± 1.0 SE). Nestlings were provisioned by both parents for 13–18 d (16.7 ± 1.6 SE). Nestlings fledged when they were slightly heavier than adult females. Compared to their European counterparts, the high-elevation redstarts had similar clutch size, incubation or nestling periods and tended to produce fewer clutches of larger eggs. This suggests a life history strategy adapted to maximize offspring survival in the harsh highland environments. Most nests were attended by one male and one female, while at several nests the pair was accompanied by a third individual in female-like plumage. One of these helpers was molecularly sexed as a male and its plumage pattern indicated it to be a yearling. Such cooperative groups occurred in two of the 12 closely monitored nests and two additional nests based on opportunistic observations. One of the four trios was confirmed to raise two broods during a single breeding season and another produced the seven-egg clutch. This is the first confirmation of cooperatively breeding among the 11 Phoenicurus species.

We describe an observation of Griffon Vultures Gyps fulvus killing and eating a conspecific in Álava, northern Spain. We put this observation in the context of previous reports of cannibalistic behaviour in vultures. The reduction of livestock carcasses available to scavengers in the wild, a result of the carcass removal policy adopted by EU countries after the bovine spongiform encephalopathy (BSE) outbreak, could have contributed to this behaviour.