Seasonal Patterns of Fat Deposits in Relation to Migratory Strategy in Facultative Migrants

Physiological preparations for migration generally reflect migratory strategy. Migrant birds fuel long-distance flight primarily with lipids, but carrying excess fuel is costly; thus, the amount of fat deposited prior to departure often reflects the anticipated flight duration or distance between refueling bouts. Seasonal pre-migratory deposition of fat is well documented in regular seasonal migrants, but is less described for more facultative species. We analyze fat deposits of free-living birds across several taxa of facultative migrants in the songbird subfamily Carduelinae, including house finches (Haemorhous mexicanus), American goldfinches (Spinus tristis), pine siskins (Spinus pinus) and four different North American ecotypes of red crossbills (Loxia curvirostra), to evaluate seasonal fat deposition during facultative migratory periods. Our data suggest that the extent of seasonal fat deposits corresponds with migratory tendency in these facultative taxa. Specifically, nomadic red crossbills with a seasonally predictable annual movement demonstrated relatively large seasonal fat deposits coincident with the migratory periods. In contrast, pine siskins, thought to be more variable in timing and initiation of nomadic movements, had smaller peaks in fat deposits during the migratory season, and the partial migrant American goldfinch and the resident house finch showed no peaks coincident with migratory periods. Within the red crossbills, those ecotypes that are closely associated with pine habitats showed larger peaks in fat deposits coincident with autumn migratory periods and had higher wing loading, whereas those ecotypes associated with spruces, Douglas-fir and hemlocks showed larger peaks coincident with spring migratory periods and lower wing loading. We conclude that population averages of fat deposits do reflect facultative migration strategies in these species, as well as the winter thermogenic challenges at the study locations. A difference in seasonal fattening and wing loading among red crossbill ecotypes is consistent with the possibility that they differ in their migratory biology, and we discuss these differences in light of crossbill reproductive schedules and phenologies of different conifer species.

A Revised and Improved Version of the Northern Wheatear (Oenanthe oenanthe) Transcriptome

This work presents an updated and more complete version of the transcriptome of a long-distance migrant, the Northern Wheatear (Oenanthe oenanthe). The improved transcriptome was produced from the independent mRNA sequencing of adipose tissue, brain, intestines, liver, skin, and muscle tissues sampled during the autumnal migratory season. This new transcriptome has better sequencing coverage and is more representative of the species’ migratory phenotype. We assembled 20,248 transcripts grouped into 16,430 genes, from which 78% were successfully annotated. All the standard assembly quality parameters were improved in the second transcriptome version.

FIRST REPORT ON HUNTING BEHAVIOR OF MIGRATORY ORIENTAL HONEY-BUZZARD (PERNIS PTILORHYNCHUS ORIENTALIS) TOWARDS MIGRATORY GIANT HONEYBEE (APIS DORSATA DORSATA) (HYMENOPTERA: APIDAE) ON JAVA ISLAND, INDONESIA

Both Migratory Oriental Honey-buzzard (Pernis ptilorhynchus orientalis) and migratory giant honeybee (Apis dorsata dorsata) can be found in South-east Asia. The Oriental Honey-buzzard is the main predator of the giant honeybee, prey upon its honeycomb, larvae, and honey. Its existence always follows the migration of the giant honeybee. They stay on Java island during the migratory season. The giant honeybee lives in a large colony and has a powerful sting that is useful for defence against its predators. The bee is among the most dangerous animals since its threatening defensive behavior causes severe impact on the eagle and is even frequently fatal for human beings. Data collections on hunting behavior of the Oriental Honey-buzzard were based on irregular observations and interviews between the year 2003 to 2019. We categorized five hunting behaviors during data collections: flying orientation around the bee’s nest, attack on living nest, failure to collect the living nest, preying upon the newly empty nest, and transferring attack of the angry bee to people nearby. The safest hunting for the Oriental Honey-buzzard is to prey upon newly empty nest left by the honeybee. When the nest was still occupied by the bee colonies, the eagle should develop a strategy to avoid and reduce the risk of being attacked. It sometimes transfers the attack to people nearby.

Seasonally specific changes in migration phenology across 50 years in the Black-throated Blue Warbler

The availability of detailed information that encompasses the geographic range of a species, spans a long-term temporal range, and yields individual information (e.g., age and sex), is a principle challenge in ecology. To this end, the North American Bird Banding Laboratory maintains a unique and underutilized dataset that can be used to address core questions of phenological change in migratory birds. We used records from 1966 to 2015 to quantify how the timing of migration has shifted in a long-distance migrant, the Black-throated Blue Warbler (Setophaga caerulescens). Additionally, we examined age and sex differences in the timing of migratory movements. We observed that early spring migrants passed through sites ~1.1 days earlier per decade and the peak of spring migration also occurred earlier over the 50 yr of this study. Additionally, phenological change was more rapid with increasing latitude during peak spring migratory periods. During fall, the peak of migration stayed consistent across the 50 yr studied, but the migratory season showed protraction overall. During spring, males consistently migrated earlier than females and adults migrated earlier than young individuals. During fall, there was no difference in timing between males and females, but young birds migrated earlier than adults. Additionally, migration proceeded faster in spring compared with the fall. This study reveals differential strategies in migrant timing, across seasons, age groups, and by sex, and shows that en route adjustments across latitude may account for changes in migrant timing. This basic information about such a fundamental ecological process is crucial to our understanding of migration and we must utilize these unique data to appreciate critical shifts at relevant scales of migration.

Oxidative status and metabolic profile in a long-lived bird preparing for extreme endurance migration

The high metabolic activity associated with endurance flights and intense fuelling of migrant birds may produce large quantities of reactive oxygen species, which cause oxidative damage. Yet it remains unknown how long-lived birds prepare for oxidative challenges prior to extreme flights. We combined blood measurements of oxidative status and enzyme and fat metabolism in Hudsonian godwits (Limosa haemastica, a long-lived shorebird) before they embarked on non-stop flights longer than 10,000 km during their northbound migrations. We found that godwits increased total antioxidant capacity (TAC) and reduced oxidative damage (TBARS) as the pre-migratory season progressed, despite higher basal metabolic rates before departure. Elevations in plasma β-hydroxybutyrate and uric acid suggest that lipid and protein breakdown supports energetic requirements prior to migration. Significant associations between blood mitochondrial cytochrome-c oxidase and plasma TAC (negative) and TBARS (positive) during winter indicate that greater enzyme activity can result in greater oxidative damage and antioxidant responses. However enzyme activity remained unchanged between winter and premigratory stages, so birds may be unable to adjust metabolic enzyme activity in anticipation of future demands. These results indicate that godwits enhance their oxidative status during migratory preparation, which might represent an adaptation to diminish the physiological costs of long-distance migration.

Species Diversity and Abundance of Birds along Boat Touring Routes for Ecotourism in Tha-kha Sub-District, Amphawa District, Samut Songkram Province, Thailand

Tha-kha Floating Market is a famous tourist attraction in Tha Kha sub-district, Amphawa district, Samut Songkram Province, Thailand. There are Thai paddle-boats for tourists to get close to nature and local people lifestyle along the canals. The objectives of this research were (1) to study species diversity, feeding behavior and status of birds in the research area. (2) to analyze abundance and similarity of birds in the research area. The data was carried out by field survey of species of birds and their behaviors sighted directly and from their calls by using line transect method then classify species, feeding behavior and status of birds, analyze their abundance and similarity in three routes. Three boat touring routes were surveyed; route 1 (Tha Kha floating market—homestay), route 2 (Tha Kha floating market—Thai traditional sugar making kiln), and route 3 (Thai traditional sugar making kiln—resort). The survey was conducted in the morning from 7 a.m. to 10 a.m. and in the afternoon from 3 p.m. to 6 p.m. One survey was made each month from April 2017–March 2018. The result of this research found that there were 15 orders, 37 families and 74 species of birds. The highest number of bird species in 3 routes was 49 species in December and 47 species in November accordingly because it was migratory season of migratory birds in the research area. According to bird feeding behavior, the maximum insectivorous bird species of 35 were found in 3 routes. According to status of birds, 52 resident birds, 9 migratory birds, 13 resident and migratory birds were found in 3 routes. According to bird abundance, 21 bird species were in level 5, 7 bird species in level 4, 20 bird species in level 3, 9 bird species in level 2 and 17 bird species in level 1. According to bird similarity index, the similarity index between route 1 and route 3 was 0.814. The community also organized eco-touring activities by using Thai paddle-boats. So the birds are as indicators of natural balance of local ecosystem.

Effect of illegal glass eel (Anguilla anguilla) fishery on estuarine fish stocks: a case study in the Mondego Estuary, Portugal

Illegal fishing is a critical activity that affects a wide range of species, leading to a decline in total abundance and the overexploitation of target and non-target species. In Portugal, despite fishing for eel juveniles not being allowed, a substantial amount of illegal fishing takes place during the migratory season (October–March). The aim of this study was to investigate the effects of glass eel fishing in the Mondego estuary on target and non-target species. Samples were collected between November 2011 and March 2013 during the autumn and winter (dry and regular respectively with regard to hydrological characteristics) in 2 years. No differences in glass eel catches were observed between fishing seasons; however, a higher number of non-target species was observed in 2012–13 (regular year). There was higher species diversity in the regular year, as well as the highest number of individuals. Higher catches of the most abundant species were also observed in the regular year, compared with the dry year, suggesting that the magnitude of the effect of these illegal practices is related to hydrological cycles. Despite the low replication (2 years), the present study shows that non-selective practices have considerable effects on the species captured, as well as on the functioning of the estuarine ecosystem.

Abrupt switch to migratory night flight in a wild migratory songbird

Every year, billions of wild diurnal songbirds migrate at night. To do so, they shift their daily rhythm from diurnality to nocturnality. In captivity this is observed as a gradual transition of daytime activity developing into nocturnal activity, but how wild birds prepare their daily rhythms for migration remains largely unknown. Using an automated radio-telemetry system, we compared activity patterns of free-living migrant and resident European blackbirds (Turdus merula) in a partially migratory population during the pre-migratory season. We found that activity patterns between migrant and resident birds did not differ during day and night. Migrants did not change their daily rhythm in a progressive manner as has been observed in captivity, but instead abruptly became active during the night of departure. The rapid shift in rhythmicity might be more common across migratory songbird species, but may not have been observed before in wild animals due to a lack of technology.