Breeding seabirds, often nest at high densities and supply large amounts of marine-derived nutrients, such as nitrogen, in their feces into the ecosystems surrounding their breeding colonies. It has been well demonstrated that the nitrogen supplied by seabirds (seabird-N) into terrestrial ecosystems has a strong bottom-up effect on both producers and consumers. The seabird-N can reach into the surrounding marine ecosystems near the colony through multiple pathways including the surface run-off of rainwater or leaching by ground water. However, in marine ecosystems the bottom-up effects of seabird-N have been rarely documented. A few studies using stable isotope analyses have reported that seabird-N enhances the productivity of both phytoplankton and macro algae. There have been more limited studies documenting similar positive effects of seabird-N on marine consumers. Very little is known about spatio-temporal variations in the effects of the seabird-N on marine ecosystems. To understand the ecosystem functions of seabirds in marine nutrient cycling and the bottom-up effects of seabird-N in marine ecosystems, further research is necessary.
A high demand for palm oil has led to the continued expansion of oil palm agriculture at the expense of tropical forests and forest biotic communities in many developing countries. The response of wildlife to oil palm establishment has been shown to vary according to taxa, and many forest species may not be able to adapt to the altered landscape. Many nocturnal bird species have been recorded in oil palm agriculture. Whether such forest species can also thrive in such a landscape is not known, and their responses to habitat complexity are poorly understood. We conducted point surveys of nocturnal birds (Tytonidae, Strigiformes and Caprimulgiformes over 80 points spaced at least 800 m apart and revisited five times) in oil palm smallholdings at Tanjung Karang, Kuala Selangor. Environmental factors measured at each point included: average height of oil palm stands, palm density, crop richness, and distances to the nearest forest, river and road. We recorded a total of 577 individuals of seven species. Palm density and distance to river were found to positively influence nocturnal bird species richness, whereas distance to the nearest forest was found to negatively influence avian species richness. In the case of abundance, number of oil palms, crop richness, and distance to the nearest river were found to influence nocturnal bird abundance positively in the smallholdings; however, distance to the nearest forest was found to influence bird abundance negatively. These findings suggest that maintaining key vegetation structure while reducing manmade structures such as roads may benefit nocturnal bird species in the smallholdings particularly those of open and semi-open habitats. However, the number of forest-associated species remained low in the smallholdings, which may only serve as suboptimal habitat for these birds. This implies that forest-associated species may not be able to persist in such landscapes.
Habitat degradation and fragmentation are serious threats to global biodiversity. Attributes of vegetation structure and patch structure have been considered critical factors in sustaining species diversity, but their relative importance remains unclear. This study aimed at identifying key vegetation and patch structure variables for bird species richness and examining their relative importance. We surveyed and mapped all individual birds in a 50-ha forest-farm landscape mosaic over three breeding seasons and recorded the vegetation in 286 patches of six land-use types. Native forests and conifer plantations (covering 59% of the area) contained 89% of the individuals and all of the bird species recorded. The effects of vegetation structure variables, tree family richness, and foliage coverage were more significant than those of patch-structure variables. Although conifer plantations were low in tree family richness of the canopy layer, they had a high tree family richness in the sub-canopy layer, and had similar bird density and species richness values as native forests. Creating and maintaining patches with a complex vegetation structure are critical for supporting animal abundance and species diversity. Forest patches dominated by only a few tree species in the canopy layer can be greatly improved by increasing the floristic composition of the sub-canopy layer. Large patches with a complex vegetation structure are important for sustaining biodiversity and should be kept as intact as possible.
Layyah City is located along the River Indus and provides rich habitat for a wide range of resident and migratory bird species. The present study documents for the first time the avifaunal diversity and abundance of urban and riverine sites of Layyah. Potential habitats around the city were identified and three study sites were selected, one in each of the main habitat types. A total of 223 species was recorded: 92 residents, 87 winter visitors, 42 passage migrants and two new records from the area. A Shannon Wiener Index of 4.36 indicates that the area has a high level of biodiversity. Of the species recorded, 16 are included in the IUCN Red list as vulnerable (N=6), near threatened (N=9) or endangered (N=1). The most abundant species were House Crow Corvus splendens, House Sparrow Passer domesticus, Common Myna Acridotheres tristis and Common Starling Sturnus vulgaris. Two species, Houbara or McQueen's Bustard Chlamydotis macqueenii and Black-headed Ibis Threskiornis melanocephalus were recorded for the first time from the area. Potential threats to the avian diversity of the area are hunting, habitat loss, and pollution.
Species are capable of flexible energy allocation in response to changes in food availability. The extent to which individuals are able to adjust their energy allocation is presumed to be dependent on individual quality. Individuals of lower quality (i.e. better physiological condition) may be at an energy ceiling, and lack the reserves available to be able to expend more energy when environmental conditions deteriorate. Using the doubly labeled water method, we measured the field metabolic rates of free-ranging Black-tailed Gulls Larus crassirostris incubating two- and three-egg clutches during two consecutive years. Lower sea surface temperatures in 2013, compared with those in 2012, provided indirect evidence of poorer food availability in 2013 than in 2012. Parent gulls incubating three-egg clutches were able to increase their energy expenditure, in response to the poor food conditions in 2013, whereas those incubating two-egg clutches were not. Within a gull population we found heterogeneity of the energy allocation process in response to changes in food availability.
The Lord Howe Woodhen (Hypotaenidia sylvestris) is endemic to Lord Howe Island off the mid-east coast of Australia and came perilously close to extinction as a result of hunting pressure and introduced predators. A recovery program was implemented in the 1970s to reverse the decline of the species through eradicating introduced predators (pigs, cats and goats) and augmenting the population through an in situ captive-breeding program. In 1980, three wild breeding pairs were taken into captivity from Mount Gower. Over the four years of the captive-breeding program, 76 chicks were produced from the original founders and their progeny and an additional four chicks were artificially reared from eggs collected from a wild pair. Almost all woodhens were liberated across four release sites, but only 13% of released birds were resighted and numbers increased at only one of these sites and then declined. A captive-bred female that was released into the lowlands paired with a wild male (which had been temporarily held in captivity) and bred prolifically, leading to rapid population growth in the lowlands. The subpopulation on Mount Gower increased fivefold in the decade following the captive-breeding program, despite the removal of the three breeding pairs (which were released elsewhere) and receiving no augmentation from the captive-breeding program. The woodhen population continues to expand and it is likely the eradication of invasive rodents from Lord Howe Island during 2019 will facilitate further population growth.
The aim of our study was to describe the migration timing of two Siberian Locustella species at a breeding site in the Russian Far East. Our results show, that juvenile Lanceolated Warbler Locustella lanceolata leave the study site earlier than adults, while juvenile Pallas's Grasshopper Warbler L. certhiola start their migration later than adults, which might be caused by juveniles and adults moulting at different times. Both species undertake a fast migration without long-term stopovers at the study site.
We investigated the division of provisioning between Fieldfare Turdus pilaris mates as well as synchronisation and alternation of parental feeding trips. We found that parents equally participated in provisioning of older nestlings, but males provisioned young nestlings more than their mates. Synchronisation between parents was higher during the early nestling stage, when they alternated more than during the whole nestling stage. During the early nestling stage alternation was correlated with parental share in provisioning, suggesting that alternation may ensure more equal participation of each parent in provisioning. However, we did not find an analogous relationship between alternation and provisioning during the late nestling stage.
To identify drivers of local variation in breeding success in colonial seabirds, we studied the role of breeding phenology and parental quality on the breeding performance of two neighbouring subcolonies of Streaked Shearwaters Calonectris leucomelas, with similar habitat but different success. Egg dimension and parental quality during incubation, but not phenology, predicted hatching success. Birds at the low-success colony laid smaller eggs, reared smaller chicks and neglected eggs more frequently, leaving them vulnerable to predation. Our findings suggest that local variation in breeding performance in this species arises from differences in breeding quality, perhaps driven by age or experience.
In the springs of 2016–2017, 42 nests of the Syrian Woodpecker Dendrocopos syriacus were surveyed in 400 ha of the mountainous region of southwestern Iran. Egg laying began in late March. Clutch size was between three and five eggs (mean: 4±0.6, median: 4, N=26). The incubation period varied from nine to 13 days (mean: 10.7±1.2 days). Hatching most often occurred in the last two weeks of April. The number of eggs that hatched in successful nests (N=25) was 2–5 (mean: 3.6±0.9), and hatching percentage (N=26) was 66.4%. The duration of the nestling period was 25–28 days (mean: 25.9±0.05 days), with fledging dates ranging from 7 May to 29 June, with most chicks fledging in mid-May. The number of ﬂedglings from successful nests (N=19) was 1–5 (mean: 3.2±1.1), whereas the mean number of ﬂedglings from all nests (N=35) was 1.7±1.8. The percentage of successful nests (at least one ﬂedged young, N=19) was 54.3%. European Starlings Sturnus vulgaris caused the failure of two nests in 2016 and 12 nests in 2017, resulting in nesting success of 81.3% in 2016 but only 31.6% in 2017. The overall duration of breeding varied from 38 to 44 days (mean: 40.4±1.8 days).
Knowledge of the feeding behavior of omnivorous migrant birds is important to understand their migration ecology. This study revealed the dietary habits of the Pale Thrush Turdus pallidus overwintering on Okinawa-jima Island, Japan. Food items consumed were determined from the contents of the gizzards of 32 birds; at least 24 animal and eight plant species were identified. The contents of 84.4% of the studied gizzards were dominated by a single species or item. The Pale Thrush forages on various animals and plants, but in its winter habitat it feeds extensively and exclusively on select food items within a short period.
The migratory strategies of kingfishers are poorly understood. In the first study of its kind, by means of Global Positioning System data loggers, we were able to describe the migration and wintering sites of the Ruddy Kingfisher Halcyon coromanda population breeding on Miyako Island, Japan. Birds were found to reach altitudes of almost 4,000 m during their migration to winter on Polillo and Tablas islands in The Philippines.