Behavioral responses of nesting birds to human disturbance along recreational trails

ABSTRACT The presence of recreational trails can impact breeding birds either indirectly by altering habitat or the movement patterns of predators or directly if the presence of humans disturbs birds. We examined the behavioral responses of nesting female Northern Cardinals (Cardinalis cardinalis) to human disturbance using both experimental and observational approaches. From April to August 2006 and 2007, we monitored Northern Cardinal nests in 18 riparian forests in Ohio, USA. Two experimental trials were conducted at each nest (N= 63), with Flight Initiation Distance (FID, the distance at which a bird flushed from the nest) recorded as we approached nests by walking directly toward them and by walking along trails located variable distances from nests. We also measured flight initiation distance (FID) when nests were approached during routine nest checks (N= 160). Cardinals were six times more likely to flush when nests were approached directly, and females on higher nests were less likely to flush regardless of distance to trail. FID was not significantly influenced by the distance of nests from trails. We found no association between nest survival and the tendency of birds to flush. Rather, nest survival was best explained by nest height. Thus, our findings suggest that the responses of birds to human use of recreational trails have only short‐term effects, with no apparent effects of on nest survival. Because the reaction of birds to humans in our study depended on how nests were approached, studies where FID is used as an indicator of sensitivity to human disturbance and is determined by direct approaches may overestimate the potential impact of trails on nesting birds.     

Breeding performance of gentoo penguins (Pygoscelis papua) at a colony exposed to high levels of human disturbance

Port Lockroy, situated on the Antarctic Peninsula, is one of the most visited tourist sites in Antarctica. The effects of visitor disturbance on the breeding performance of gentoo penguins (Pygoscelis papua) at Goudier Island, Port Lockroy was investigated during the austral summer of 1996/1997 by comparing pairs in treatment areas (visited by 35–55 tourists every 1–2 days) and control colonies (not visited by tourists). There were no differences between the two groups in the proportion of birds that laid, in hatching success or the proportion of single-chick broods. Pairs in treatment colonies laid a higher proportion of single-egg clutches, but this was related to colony location and unusually high snow accumulation. Most treatment colonies were situated on low-lying ground or in the lee of buildings, and probably had more late layers at the initial census. Only 11% of tourist visits had occurred by laying, making human disturbance an unlikely explanation for the higher proportion of single-egg clutches. Nests monitored in a disturbed colony and a control colony showed no differences in chick mass or survival up to 20 days of age. The overall breeding success, based on counts of creched birds, was similar to other southern populations of gentoo penguins, after correcting for mortality between creching and fledging. Historical data from Goudier Island indicate that the colony established itself in 1985 and has rapidly increased in size since then. The neighbouring colony at Alice Creek, which has been regularly visited by tourists for at least a decade, has also shown a population increase, although this expansion has been at a slower rate. We conclude that disturbance from tourist visits is unlikely to have been a major determinant of gentoo population change at Port Lockroy. Accepted: 8 November 1998     

Effect of Approaching Boats on Nesting Black Skimmers: Using Response Distances to Establish Protective Buffer Zones

ABSTRACT Understanding how birds respond to the activities of people is an important component of conserving wildlife. We measured responses of nesting black skimmers (Rynchops niger) to an approaching boat in Barnegat Bay, New Jersey, USA, by examining distance to first respond, distance to flush, and time to return to the colony. Our objective was to determine if response distances of skimmers changed as a function of year, reproductive stage, direction of approach (direct or tangential), or number of birds nesting in the colony. Generally, reproductive stage had the greatest effect on all responses, followed by direction of approach, number of adults present at the colony, number of nests, and year, which also explained variation in behavioral responses. The distance at which skimmers first flew when a boat approached decreased from the pre-egg-laying period to hatching, and then increased slightly later in the season. Time (x̄± SE) for skimmers to return to the nesting colony varied seasonally, with birds taking longer to return during the pre-egg period (9.5 ± min) than during hatching (0.7 ± 0.1 min). The decision process for determining set-back distances to protect nesting skimmers should involve selecting 1) behavioral response of highest concern, 2) reproductive stage of highest concern, and 3) an appropriate level of response at which to establish the buffer area. We recommend that managers use a set-back distance of ± 118 m from the perimeter of the colony for black skimmers, which is the 95% percentile of the distance that skimmers first flew in response to approaching boats. Managers can use these data to set buffer distances for skimmers and other colonial birds.     

Using flight initiation distance to evaluate responses of colonial‐nesting Great Egrets to the approach of an unmanned aerial vehicle

Remote‐controlled, unmanned aerial vehicles (UAVs) can be used to collect information in difficult‐to‐access places while potentially minimizing human disturbance. These devices have been widely used in a variety of ecological and behavioral studies in recent years, but additional study is needed to assess the magnitude of disturbance they cause to birds. We examined the responses of Great Egrets (Ardea alba) to a UAV in a breeding colony in Louisiana in 2016 where isolated patches of common reed (Phragmites australis) were used as nest sites by multiple breeding pairs. We examined the flush responses and flight initiation distances (FIDs) of nesting adults to the direct vertical approach of a UAV. Incubating adults were more likely to flush from nests and flushed at greater distances when approached by a UAV than adults with nestlings, suggesting that adult assessment of risk was based on the greater reproductive value of nestlings. We observed fewer flush responses and calculated lower set‐back distances using a UAV to approach nesting Great Egrets (~50 m) than set‐back distances calculated using traditional methods of approach (e.g., walking or boating; 87–251 m). We found that FIDs were shorter when more adults were present in nesting patches, suggesting that the perception of predation risk may be based in part on the reactions of other birds. Our results suggest that UAVs may be a useful alternative for monitoring colonial‐nesting waterbirds. However, our analyses were based exclusively on behavioral observations. Additional studies of the physiological responses of birds to the approach of UAVs are needed to better understand the stress responses of birds to these devices.     

Disturbance-dependent Yellow-legged Gull (Larus michahellis) predation on Larid chicks decreases with chick age

Predation is one of the key factors shaping the dynamics of animal populations. In birds, nest loss due to predation can be a significant cause of low reproductive success. Ground-nesting birds are among the bird groups most susceptible to predation, mainly because their nests are easily accessible to a broad suite of potential predators. For these birds, anthropogenic disturbances can generate changes in nest predation risk by altering their antipredator behaviour and also by altering the behaviour of the predator species, i.e. the predator becoming much more aware of predation opportunities due to frequent disturbances and/or motivated to repeat predation attempts when some are successful. To date, most previous studies investigating this have focused on a single effect, either predation or disturbance, on chick survival. It remains unknown how the risk of predation with and without disturbance varies with chick age. In this study, we used behavioural observations to assess how the interaction between predators and disturbance affects predation risk in chicks and how this interacts with chick age. Specifically, we investigated the effect of disturbance caused by humans and stray dogs on the predation of Slender-billed Gull Chroicocephalus genei chicks by Yellow-legged Gulls Larus michahellis, and whether this depended on the age of the chicks. Our results revealed that disturbance had a significant positive effect on predation measures of Slender-billed Gull chicks by Yellow-legged Gulls, but that this effect was mediated both by disturbance type and the age of chicks. Stray dogs entering the colony had a stronger disturbance effect on chicks than passing humans, increasing predation risk by Yellow-legged Gulls. Our results also showed that chick age interacts with disturbance type to determine the predation risk. This is probably mediated by chicks' capacity to escape predation by gathering in a single large crèche that runs into the water when disturbed. To preserve Slender-billed Gull colonies in one of its few remaining breeding sites in Tunisia, and as gulls tend to react even when the disturbance occurs relatively far from the colonies, it is crucial to (1) restrict human access to dikes and islets where large colonies breed and (2) construct artificial islets attractive to gulls and inaccessible to stray dogs.     

The effect of close approaches for tagging activities by small research vessels on the behavior of humpback whales (Megaptera novaeangliae)

Small research vessels are often used as platforms for tagging activities to collect behavioral data on cetaceans and they have the potential to disturb that group or individual. If this disturbance is ignored, results and conclusions produced by that study could be inaccurate. Here land‐based behavioral data of migrating humpback whales (Megaptera novaeangliae) (n = 29) were used to determine the effect of close approaches for tagging by research vessels on their diving, movement and surface behaviors. Groups of whales were tagged, using digital recording tags, by small research vessels, as part of a behavioral response study. In groups that were approached for tagging, temporary changes in movement behaviors during close approaches were found, with subsequent recovery to “pre‐approach” levels. In female‐calf groups more long‐term changes in travel speed were found. Results suggest that, although close approaches for tagging by small vessels may cause behavioral changes in humpback whales, this change may be small and temporary. However, in female‐calf groups, the behavioral change may be greater and longer lasting. This study shows that when using small vessels for behavioral research, disturbance, and recovery should be measured to ensure integrity of data used for other analyses.     

The effects of loggers on the foraging effort and chick-rearing ability of parent little auks

We studied the effects of loggers attached to chick-rearing little auks (Alle alle) on their daily time budget (proportion of time spent in the colony and at sea), foraging activity (duration and proportion of long and short foraging flights), chick provisioning rate and their growth and development on Spitsbergen. We found that experimental parent birds performed shorter but more frequent long foraging flights and reduced the frequency of short foraging flights. They spent more time at the colony and reduced chick provisioning rate compared to control birds. Nestlings reared by experimental parents weighed significantly less at their middle, peak and fledging age and departed colony later than chicks of control parents. Little auks depend on energy-rich copepods associated with cold Arctic waters and are expected to face the climate-induced worsening of the foraging conditions, which may have negative impact on their time/energy budget and survival. The study may help to determine the level of extra effort little auks need to invest to breed successfully.     

Distance from Water,Sex and Approach Direction Influence Flight Distances Among Habituated Black Swans

In many animals, response to predators occurs at greater distances the further an individual is from a refuge, but this has rarely been investigated in birds. Here, we test the hypothesis that the further from refuge (i.e. water) a foraging black swan Cygnus atratus is situated, the longer its flight initiation distance (FID) in response to a pedestrian approach on land. As predicted, swans situated farther from water exhibited longer FIDs compared with those closer to the shore. In addition, there was the possibility of an interesting interaction effect (p < 0.061) of sex and direction of approach on FID. Whilst males tended to not alter their response in relation to the angle of approach relative to the water, females tended to respond at longer distances, when approached from the shore than when approached from the land or parallel to the shore. This is one of the first reports of sex differences in FIDs for birds, with sex differences only manifesting themselves under certain approach types. Group size, the order of repeated approaches, and time of day did not influence responses, although starting distance of approach was positively related to FID.     

Effects of vegetation on nest microclimate and breeding performance of lesser black-backed gulls (Larus fuscus)

For birds that breed in large colonies, the overall area occupied by the colony generally comprises several sub-areas that differ in physical and social features such as vegetation and breeding density. Birds arriving at a breeding colony select their nesting sites through a hierarchical process of selecting a sub-area, then a particular nest site with appropriate biotic and physical attributes. Optimal vegetation cover is one such important attribute. Many ground nesting gulls preferentially select nest sites that provide shelter during reproduction, but this presumably has to be balanced against any costs such as reduced visibility of potential predators. The effects of vegetation height in the sub-areas within a colony, and of the amount of vegetation in the immediate vicinity of the nest on nest microclimate were investigated in lesser black-backed gulls Larus fuscus in a colony in which overall vegetation height differed in different sub-areas and was patchily distributed within these areas. Tall vegetation did have a sheltering effect, and this was positively related with chick growth. However, this vegetation area was associated with lower breeding densities, relatively late laying birds and lower chick survival rate, suggesting that sub-areas with tall vegetation held more lower-quality or young breeders. Within the sub-areas, the birds preferentially selected nest sites with more surrounding vegetation, and this was positively correlated with their hatching success.     

THE BREEDING BIOLOGY OF THE GANNET SULA BASSANA ON THE BASS ROCK, SCOTLAND

The Bass colony is increasing—in 1962 there were 5,350–5,700 breeding pairs; 1,340–1,430 pairs of non-breeders with nests or sites (mainly pairs in their season before first breeding) and 2,000–2,500 “club” birds without nest or site. 15% of nests were occupied by both birds of a pair at the time of the count. Oldest males return to the colony in January, followed by experienced females, considerably later by young adult-plumaged birds, immature birds later still, and the few one year-olds that return usually not until May and June. Mid-cliff sites are the first to be re-colonized each year. Gannets usually breed in their fifth year and there is some evidence that females breed earlier than males. The characteristics of Gannet nests and sites are described. Nests function in raising the egg and young above the morass of the breeding colony, and reach a density of about 2.3 per square metre. Nests are demolished and their positions changed more often than might be suspected. The extremely strong social tendency which causes Gannets to establish their sites amongst or very close to existing breeders probably is the factor ensuring high density and this contributes to synchronization of laying. Egg laying is analysed. Experienced pairs forming an isolated group of 20 nests began laying later and showed less synchronization than two other groups of the same size but from the middle of a dense mass, probably due to the greater social stimulation experienced by the non-isolated groups. The date for first and median eggs was also earlier in larger than smaller groups in the same year. The effect of density as distinct from group size is also discussed. Early eggs are mainly laid on cliff or cliff-edge sites and in large nests. Different groups within the colony produced the median egg within 2–3 days of the end of April each year. In the fullest documented group the mean date was also constant from year to year and closely approached the median, implying a considerable degree of synchronization within the gannetry as a whole. Laying in the observation colony became progressively earlier in successive years, probably due to recovery from previous disturbance. Nevertheless, individual females tended to lay in a fixed position each year with relation to the mean for the group. Increasing age of the female causes earlier egg laying and heavier eggs for up to at least five years. It is suggested that the survival value of seasonally synchronized laying in the Gannet is maximum utilization of a seasonally dependable and abundant food supply for the production of young with the optimal chance of post-fledging survival. The spread of laying acts as an insurance against possible adverse conditions. There is a considerable reserve of unutilized breeding capability within the colony (adult non-breeders, a pre-maturity period longer than physiologically necessary for egg production, and a one-egg clutch when in fact two young can easily be reared). The mean of 393 Gannet eggs was 104.5 gm. (range 81–130). Eggs constitute about 3.4% of adult female weight and lose 9–13% in weight during incubation. Replacement laying of the invariable one-egg clutch takes 6–32 days. The mean incubation period was 43.6 days. Male incubation spells averaged 35.6 hours; female's 32.0 hours. Copulation ceases immediately after egg laying. During three seasons, 82% of eggs laid in the observation colony hatched. Inexperienced pairs hatched 62.6% of eggs laid; experienced pairs hatched 86%. Some of the processes of incubation and chick rearing depend on the maturation of innate abilities and not on experience Inexperienced breeders do not seem inferior to experienced ones in finding enough food for their young. Parental care of the new chick is described; the pterylosis of the chick is figured. A summarized account of plumage development is given. Food fish and chick feeding are described. The average frequency of feeds throughout a continuous two-day watch was 2.7 feeding bouts per chick per day. Adult fishing trips usually took 7–13 hours and the estimated fishing range is over 100 miles, and possibly up to 400 miles, from the breeding colony. Despite this, 15% of daylight hours are spent by the pair together at the nest in addition to the constant guarding of the chick by one or other. Gannet young have a very compressed growth period compared with boobies and fledge at 3,100–4,100 gm., after a steady growth uninterrupted by periods of starvation or arrested development after an average 90 days. 92.3% of all eggs which hatched in 500 nests in the observation colony during three years of the study gave fledged young. Excluding inexperienced birds, there was no difference in the fledging success of eggs laid at different dates in the breeding season, in accordance with the proved abund- ance of food. However, post-fledging survival is probably higher among young fledging at the peak period (first half of September) than later and the few relevant ringing returns tend to support this. Breeding success at the small colony at Bempton was less compared with groups from the Bass for the years 1961–3. Causes of chick loss before and during fledging are discussed. They are unimportant compared with the great mortality in the first year of life after fledging. The adaptive significance of black plumage in the juvenile Gannet probably lies in reduced attack-releasing qualities of such plumage on the male parent. The Gannet alone in the Sulidae produces young which leave the nest with large fat deposits, and which are not fed at all by the parents after fledging. This is possibly another result of adaptation to using a seasonally abundant food supply to the maximum. The present Gannet population increase is discussed in relation to cessation of human predation, the possible impetus given by a temporary but large increase in pelagic fish during the war, but also the overall steady downward trend in fishing returns since the early part of this century. One cannot explain the steady and considerable rise in Gannet numbers only in terms of increased food supply. The fact that, at a time of population expansion and obviously favourable conditions, Gannets are still far from utilizing their full recruiting powers, needs investigating further. It may be partly due to the relative slowness of evolutionary change in a long-lived species with slow population turn-over, if the Gannet has evolved its characteristics in response to an environment different from the present one.     

Investigator disturbance reduces reproductive success in Short‐tailed Shearwaters Puffinus tenuirostris

Research procedures can have a detrimental effect on the reproductive success of the study species. In this study, the frequency of investigator disturbance on Short‐tailed Shearwaters Puffinus tenuirostris was examined experimentally throughout the incubation period to assess whether disturbance influences hatching success, pre‐fledging chick survival and chick body size. Handling of incubating birds every day, every 3 days and once a week reduced hatching success by 100, 61 and 39%, respectively, compared with pairs that were not disturbed. Most failures resulted from egg abandonment by the parents, particularly during the early stage of incubation. Chick survival did not differ between treatment groups, but control chicks were significantly heavier and had larger bill depths and longer wings. The difference in chick body mass and size observed between the control and disturbed chicks might be due to physiological or behavioural mechanisms in adults or carry‐over effects from the incubation stage to the next life‐history stage. Reduced offspring quality has the potential to affect post‐fledging survival and recruitment. These findings are significant in broader terms because any investigator disturbance that reduces reproductive success, survival and offspring fitness could interfere with the accurate assessment of demographic parameters and exacerbate population declines.     

Behavioural responses of South American fur seals to approach by tourists - a brief report

I studied the responses (retreats, threats, attacks or leaving the rookery) of South American fur seals Arctocephalus australis to tourist approaches at a non-reproductive, continental colony of located in Cabo Polonio, Uruguay (34 degrees 24'S, 53 degrees 46'W). Fur seals tolerated relatively close distances to humans, but a strong response of the animals was elicited when tourists crossed a threshold of 10m. The attitude of the tourist was also important. Calm people were able to approach the colony without almost any disturbance. These results suggested that, with a minimal control of visitor's behaviour, the impact of tourism on this colony would be low.     

Exclusion of ground predators improves Northern Lapwing Vanellus vanellus chick survival

Many farmland‐breeding wader species have declined across Europe, probably due to reductions in reproductive output caused by high nest losses as a result of agriculture or predation, or low chick survival between hatching and fledging. Most studies have focused on nest failures, and the factors affecting post‐hatching survival of chicks are poorly known. In an experimental approach, we fenced parts of the arable foraging areas of Northern Lapwing Vanellus vanellus families to quantify chick survival simultaneously in the presence and absence of ground predators. Lapwing chicks were radiotagged to estimate survival probabilities by daily locations, applying multistate capture–recapture models. During the night, chick survival was considerably lower outside fenced plots than within. During the day, chick survival was higher than at night and did not differ between protected and unprotected plots. This suggests that nocturnal ground predators such as Red Foxes Vulpes vulpes were responsible for a significant proportion of chick mortality. Cumulative survival probability from hatching to fledging was 0.24 in chicks within fenced plots, but virtually zero in chicks outside fenced plots. In farmland, temporary electric fences can be effective in minimizing the impact of ground predators and offer a promising short‐term method to increase fledging success of precocial birds.     

Massive breeding failures following a tsunami in a colonial seabird

Natural catastrophic events such as tsunamis may induce drastic decreases in breeding success of animal populations. We evaluate the impacts of flooding on the reproductive success of king penguins (Aptenodytes patagonicus) in the Crozet Archipelago. On 26 December 2004, a magnitude-9 earthquake created a large tsunami that flooded a colony at 6,500 km from the epicentre of the earthquake. On 30 January 2005, severe waves again flooded the colony. About 17–20% of the surface of the colony was impacted during each flood and 44% of the breeding birds abandoned their egg or chick following the two floodings. Although about 11% of birds laid another egg after the tsunami, none reproduced again after the second flood that happened later in the breeding season. Our results show that the tsunami directly affected the reproductive success of seabirds nesting near the coast.     

An experimental assessment of the potential effects of human disturbance on Black Grouse Tetrao tetrix in the North Pennines,England

In the United Kingdom, Black Grouse Tetrao tetrix have declined in range and abundance during the 20th century. In England at present, birds are largely found only on the margins of managed grouse moors in the north, where more than 80% of birds are confined to the North Pennines Area of Outstanding Natural Beauty. The Black Grouse is one of a group of species potentially at risk from increased human recreational disturbance owing to their threatened status and their use of habitats to which a statutory right of human recreational access has recently been granted. To assess the likely impact of increased disturbance to Black Grouse, 77 were caught and radiotagged between 2002 and 2004, and each was randomly assigned to one of three experimental disturbance categories: no disturbance (low), fortnightly disturbance (moderate) or twice weekly disturbance (high). Birds that were disturbed more regularly flushed at greater distances, especially in spring and winter when birds exposed to high disturbance flushed at 32% greater distances than those in moderate disturbance treatments. There were no differences in fecundity (clutch size, hatching success, breeding success) or survival between disturbance treatments. Winter survival was 78% and summer survival 92%. There was no age‐related difference in survival. The disturbance regimes imposed had no discernible impact upon Black Grouse population dynamics. However, in the absence of appropriate data to indicate likely changes in patterns and levels of human recreation resulting from open access, we cannot be sure whether the levels we applied will be representative in the future. Should actual disturbance levels be higher than those we used in this study, we list visitor management options that may help reduce any conflict that arises.     

Short-term responses of king penguins Aptenodytes patagonicus to helicopter disturbance at South Georgia

The short-term behavioural effects of helicopter overflights on breeding king penguins Aptenodytes patagonicus at South Georgia were examined. Seventeen helicopter overflights were made at altitudes between 230 and 1,768 m (750–5,800 ft) above ground level. Noise from the aircraft engines and helicopter blades increased sound levels in the colony from a background level of 65–69 dB(A) to a maximum mean peak level of 80 dB(A) during overflights. Penguin behaviour changed significantly during all overflights at all altitudes compared to the pre- and post-flight periods. Pre-overflight behaviour resumed within 15 min of the aircraft passing overhead and no chicks or eggs were observed to be taken by predators during overflights. Non-incubating birds showed an increased response with reduced overflight altitude, but this was not observed in incubating birds. Variability in overflight noise levels did not affect significantly the behaviour of incubating or non-incubating birds. Penguins exhibited a reduced response to overflights as the study progressed (despite later flights generally being flown at lower altitudes) suggesting some degree of habituation to aircraft. To minimise disturbance to king penguins we recommend a precautionary approach such that overflights are undertaken at the maximum altitude that is operationally practical, or preferably are avoided altogether.     

The effects of investigator disturbance on procellariiform seabirds: A review

Abstract

Despite long‐held concerns about the effects of researchers on breeding birds, few studies have focused on the impact of investigators on Procellariiformes. In this review, we summarise published investigations concerning the effects of investigators on physiology, behaviour, reproductive success, offspring quality, and population trends of procellariiform seabirds. Many of the smaller procel‐lariid taxa, such as storm‐petrels (Hydrobatidae, and some shearwater Puffinus species) are particularly sensitive to handling during the incubation period, resulting in lowered reproductive success, burrow shifts, and increased divorce between pairs. However, repeated handling of chicks does not seem to have a discernible effect on chick quality. In larger procellariiforms, the presence of researchers within the breeding colony is associated with significant increases in heart rates. Therefore, researchers seeking unbiased estimates of demographic and ecological parameters of birds should be encouraged to measure their own impact and report the findings in the literature, even if they detect no adverse effects of investigator disturbance. Techniques should be developed that ensure the accurate recording of birds’ natural behaviour while minimising the impact of investigator disturbance. If investigators are willing to study disturbance problem s, it should be possible to reduce biases caused by their activities.     

Foraging strategy of the little auk Alle alle throughout breeding season – switch from unimodal to bimodal pattern

Energy and time allocation differs between incubation and chick‐rearing periods, which may lead to an adjustment in the foraging behaviour of parent birds. Here, we investigated the foraging behaviour of a small alcid, the little auk Alle alle during incubation and compared it with the chick‐rearing period in West Spitsbergen, using the miniature GPS (in Hornsund) and temperature loggers (in Magdalenefjorden). GPS‐tracking of 11 individuals revealed that during incubation little auks foraged 8–55 (median 46) km from the colony covering 19–239 (median 120) km during one foraging trip. Distance from the colony to foraging areas was similar during incubation and chick‐rearing period. During incubation 89% of foraging positions were located in the zone over shallower parts of the shelf (isobaths up to 200–300 m) with sea surface temperature below 2.5°C. Those environmental conditions are preferred by Arctic zooplankton community. Thus, little auks in the Hornsund area restrict their foraging (both during the incubation and chick‐rearing period) to the area under influence of cold, Arctic‐origin water masses where its most preferred prey, copepod Calanus glacialis is most abundant. The temperature logger data (from 4 individuals) indicate that in contrast to the chick‐rearing period, when parent birds alternated short and long trips, during the incubation they performed only long trips. Adopting such a flexible foraging strategy allows little auks to alter their foraging strategy to meet different energy and time demands during the two main stages of the breeding.     

Variation in Note Composition of Chick‐a‐dee Calls is Associated with Signaler Flight in Carolina Chickadees,Poecile carolinensis

Chick‐a‐dee calls are used in a wide range of social contexts in Poecile (chickadee) species. These calls comprise a number of distinct note types. Earlier naturalistic observational studies suggested that the ‘C’ note type was used frequently in calls of Carolina chickadees (P. carolinensis) in the context of flight. We conducted three field studies with Carolina chickadees to test in more experimentally manipulative ways whether Chick‐a‐dee calls with more ‘C’ notes were associated with flight. The three studies differed in how they elicited flight behavior from chickadees, as well as in the likely arousal levels experienced by the birds. First, we captured chickadees and released them, recording any calls they produced in flight or when later perched after escape. Second, we approached chickadees that were foraging near the ground in field settings and recorded any calls they produced when perched compared to when they were in flight. Third, from a distant blind, we recorded chickadees flying to and from feeding stations, in which the closest perching substrate/cover was at least 2 m away from the feeding station, thus requiring flight. In all three studies, calls contained more ‘C’ notes when birds were in flight compared to when they were perched. This work expands our understanding of variation in note composition of chick‐a‐dee calls beyond the contexts of food and predator detection to the context of movement. Studies are now needed to test whether such variation in chick‐a‐dee calls brings about group cohesion.     

Breeding ecology and behaviour of the last wild oriental Northern Bald Ibises (Geronticus eremita) in Syria

A relict colony of Northern Bald Ibis (Geronticus eremita), a critically endangered species, was unexpectedly discovered in Syria in 2002. During six subsequent breeding seasons (2002–2007), the 3, and then 2, breeding pairs of Northern Bald Ibises have shown to be still vital and, when intensively protected, showed a higher average breeding success than that recorded in Morocco, the only other country where these birds still breed in the wild. During the six breeding seasons, a total of 24 chicks fledged and left the breeding area successfully. Between 2004 and 2007, a total of 5 immature ibises have made a return to the colony, separately and later than adults. As a consequence, two recruitment events have taken place (2006 and 2007), partly compensating for the gradual decrease in the number of adults. Breeding adults arrive from migration during the second half of February, separately, and leave together around mid-July. They nest in cavities and ledges of two limestone cliffs of the central Syria desert, located 20 km apart, well protected from the predominant wind. Breeding behaviour and the cycle are described, summarised and compared with data from the wild colonies of Morocco and the colony of Turkey before the extinction. Key threats still in place at the Syrian breeding quarters are human disturbance during settling and incubation, chick depredation by ravens, uncontrolled hunting and habitat degradation. Recommendations on how to enhance the breeding performance and ensure the survival of this colony in the future are given.