Anser Indicus Research Articles

An implantable instrument for studying the long-term flight biology of migratory birds

The design of an instrument deployed in a project studying the high altitude Himalayan migrations of bar-headed geese (Anser indicus) is described. The electronics of this archival datalogger measured 22 × 14 × 6.5 mm, weighed 3 g, was powered by a ½AA-sized battery weighing 10 g and housed in a transparent biocompatible tube sealed with titanium electrodes for electrocardiography (ECG). The combined weight of 32 g represented less than 2% of the typical bodyweight of the geese. The primary tasks of the instrument were to continuously record a digitised ECG signal for heart-rate determination and store 12-bit triaxial accelerations sampled at 100 Hz with 15% coverage over each 2 min period. Measurement of atmospheric pressure provided an indication of altitude and rate of ascent or descent during flight. Geomagnetic field readings allowed for latitude estimation. These parameters were logged twice per minute along with body temperature. Data were stored to a memory card of 8 GB capacity. Instruments were implanted in geese captured on Mongolian lakes during the breeding season when the birds are temporarily flightless due to moulting. The goal was to collect data over a ten month period, covering both southward and northward migrations. This imposed extreme constraints on the design's power consumption. Raw ECG can be post-processed to obtain heart-rate, allowing improved rejection of signal interference due to strenuous activity of locomotory muscles during flight. Accelerometry can be used to monitor wing-beat frequency and body kinematics, and since the geese continued to flap their wings continuously even during rather steep descents, act as a proxy for biomechanical power. The instrument enables detailed investigation of the challenges faced by the geese during these arduous migrations which typically involve flying at extreme altitudes through cold, low density air where oxygen availability is significantly reduced compared to sea level.

Influence of HbCO Structure of the Bar-Headed Goose on Photolysis Thermodynamics as Studied by the Nanosecond Laser-Ultrasonic Technique

The bar-headed goose, a specialized high-altitude species, has a capacity for high oxygen uptake from a hypoxic environment. It thus has a higher oxygen affinity than other bird species of lower-altitude environments. Oxygen affinity is determined by molecular structures and genetic mutations of hemoglobin (Hb), which can also influence the coordinating structures and dynamics of oxygen-Hb. To explore the structural differences in Hbs as between high and low altitude species, photolysis dynamic parameters, including quantum yield, enthalpy, and conformational volume changes in carboxy-Hbs (HbCO) for the bar-headed goose and low altitude counterparts (the Chinese goose and chicken) were investigated by the laser pumping-probing technique and photoacoustic calorimetry. Comparing the photolysis results for HbCO of the three species, the enthalpy and conformational volume changes of the bar-headed goose were much smaller than those of the others, although the quantum yields of all three species are similar. To explain the possible mechanisms of these differences, modifications of salt bridges and key residue mutations at the α β subunit interfaces of the proteins are described and discussed briefly.

Experimental infection of bar-headed geese (Anser indicus) and ruddy shelducks (Tadorna ferruginea) with a clade 2.3.2 H5N1 highly pathogenic avian influenza virus.

Since 2005, clade 2.2 H5N1 highly pathogenic avian influenza (HPAI) viruses have caused infections and morbidity among numerous species of wild waterfowl in Eurasia and Africa. However, outbreaks associated with clade 2.3.2 viruses have increased since 2009, and viruses within this clade have become the dominant strain of the H5N1 HPAI virus detected in wild birds, reaching endemic status in domestic birds in select regions of Asia. To address questions regarding the emergence and expansion of clade 2.3.2 viruses, 2 waterfowl species repeatedly involved in outbreaks of H5N1 HPAI viruses, bar-headed geese (Anser indicus) and ruddy shelducks (Tadorna ferruginea), were inoculated with a representative virus. All of 3 infected ruddy shelducks exhibited neurologic signs and died within 4 to 5 days. Two of 3 infected bar-headed geese had transient weakness but all survived. Viral shedding was predominately via the oropharynx and was detected from 1 to 7 days after inoculation. The severity and distribution of microscopic lesions corresponded with clinical disease and influenza-specific immunohistochemical staining of neurons. The predominant lesions were in the brain and were more severe in ruddy shelducks. Increased caspase-3 reactivity in the brains of all infected birds suggests a role for apoptosis in H5N1 HPAI virus pathogenesis in these species. These results demonstrate that similar to clade 2.2 viruses, a clade 2.3.2 H5N1 HPAI virus is neurotropic in some waterfowl species and can lead to neurologic disease with varying clinical outcomes. This has implications for the role that wild waterfowl may play in transmission of this virus in endemic regions.

Discussing implications of fast depleting rural ponds on the globally threatened wetland winter migratory bird in Haryana: a Case Study of Nigdu village pond in Karnal District

The Nigdu-Sarovar is located in Nilokheri block in Karnal district in Haryana (29°50°N, 76°55°E). The duration of observations span over seven years (September, 2005 to March, 2012). The recording of wetland winter visitor birds during 2005-08 in winter season included atleast 58 species of birds belonging to 10 orders and 18 families. It is important to mention that 29 species of wetland birds were winter migratory, 17 residents, 9 local migratory and three species of wetland birds like Lesser-whistling Duck Dendrocygna javanica, Pheasant-tailed Jacana Hydrophasianus chirurgus and Blue-cheeked Bee-eater Merops persicus were summer migratory. The special features of 2005-06 winter was the huge populations of birds like Northern Shoveller Anas clypeata, Northern Pintail Anas acuta, Common Teal Anas crecca, Spot-billed Duck Anas poecilorhynchus, Common Pochard Aythya ferina, Bar-headed Goose Anser indicus, Greylag Goose Anser anser, Gadwall Anas strepera, Great Cormorant Phalacrocorax carbo, Mallard Anas platyrhynchos and Common Redshank Tringa totanus etc.In successive years, the scenario was more or less a substantial one depicting stability with respect to diversity of birds, number of birds upto the year of 2008. The popular birds included Painted Stork Mycteria leucocephala, Openbill Stork Anastomus oscitans, White-necked Stork Ciconia episcopus, Black-necked Stork Ephippiorhynchus asiaticus, Eurasian Spoonbill Platalea leucorodia, Spotted Greenshank Tringa guttifer and Kentish Plover Charadrius alexandrines. The sharp decline in winter migratory birds at Nigdu-Sarovar started in the year of 2008 when the pond was leased out for FISH-FARMING as per the policies of Govt. of Haryana. Fish Farming based deepening of the pond by excavation of bottom resulting in total decimation of rooted, floating, submerged and ejecting plants along with its subsidiary fauna, Zooplanktons, phytoplankton etc. The age old structural regime of the pond was obliterated to turn it in a scientifically managed fish pond. The year of 2009-10, 2010-11 and 2011-12 (March, 2012) showed the total absence of migratory birds like Mallards, several Geese, Dabbling Ducks, Pochards and Teals etc. As of today (2012), the sarovar is a clean sheet of water with bird repelling devices installed in places.

HIGH-FLYING GEESE: HOW HIGH IS HIGH?

![][1] Bar-headed geese ( Anser indicus ) migrate thousands of kilometres twice a year from their breeding grounds in Mongolia, northern China and the Tibetan Plateau to their wintering grounds in India and back again. During this migration, bar-headed geese have to fly across the

The paradox of extreme high-altitude migration in bar-headed geeseAnser indicus

Bar-headed geese are renowned for migratory flights at extremely high altitudes over the world's tallest mountains, the Himalayas, where partial pressure of oxygen is dramatically reduced while flight costs, in terms of rate of oxygen consumption, are greatly increased. Such a mismatch is paradoxical, and it is not clear why geese might fly higher than is absolutely necessary. In addition, direct empirical measurements of high-altitude flight are lacking. We test whether migrating bar-headed geese actually minimize flight altitude and make use of favourable winds to reduce flight costs. By tracking 91 geese, we show that these birds typically travel through the valleys of the Himalayas and not over the summits. We report maximum flight altitudes of 7290 m and 6540 m for southbound and northbound geese, respectively, but with 95 per cent of locations received from less than 5489 m. Geese travelled along a route that was 112 km longer than the great circle (shortest distance) route, with transit ground speeds suggesting that they rarely profited from tailwinds. Bar-headed geese from these eastern populations generally travel only as high as the terrain beneath them dictates and rarely in profitable winds. Nevertheless, their migration represents an enormous challenge in conditions where humans and other mammals are only able to operate at levels well below their sea-level maxima.

High thermal sensitivity of blood enhances oxygen delivery in the high-flying bar-headed goose

The bar-headed goose (Anser indicus) crosses the Himalaya twice a year at altitudes where oxygen (O2) levels are less than half those at sea level and temperatures are below -20°C. Although it has been known for over three decades that the major hemoglobin (Hb) component of bar-headed geese has an increased affinity for O2, enhancing O2 uptake, the effects of temperature and interactions between temperature and pH on bar-headed goose Hb-O2 affinity have not previously been determined. An increase in breathing of the hypoxic and extremely cold air experienced by a bar-headed goose at altitude (due to the enhanced hypoxic ventilatory response in this species) could result in both reduced temperature and reduced levels of CO2 at the blood-gas interface in the lungs, enhancing O2 loading. In addition, given the strenuous nature of flapping flight, particularly in thin air, blood leaving the exercising muscle should be warm and acidotic, facilitating O2 unloading. To explore the possibility that features of blood biochemistry in this species could further enhance O2 delivery, we determined the P50 (the partial pressure of O2 at which Hb is 50% saturated) of whole blood from bar-headed geese under conditions of varying temperature and [CO2]. We found that blood-O2 affinity was highly temperature sensitive in bar-headed geese compared with other birds and mammals. Based on our analysis, temperature and pH effects acting on blood-O2 affinity (cold alkalotic lungs and warm acidotic muscle) could increase O2 delivery by twofold during sustained flapping flight at high altitudes compared with what would be delivered by blood at constant temperature and pH.

Data Mining Approaches for Habitats and Stopovers Discovery of Migratory Birds

This paper focuses on using data mining technology to efficiently and accurately discover habitats and stopovers of migratory birds. The three methods we used are as follows: 1. a density-based clustering method, detecting stopovers of birds during their migration through density-based clustering of location points; 2. A location histories parser method, detecting areas that have been overstayed by migratory birds during a set time period by setting time and distance thresholds; and 3. A time-parameterized line segment clustering method, clustering directed line segments to analyze shared segments of migratory pathways of different migratory birds and discover the habitats and stopovers of these birds. Finally, we analyzed the migration data of the bar-headed goose in the Qinghai Lake Area through the three above methods and verified the effectiveness of the three methods and, by comparison, identified the scope and context of the use of these three methods respectively.

Analysis of avian-biodiversity in rural wetland environs in Panipat district in Haryana, India

The present study has observed 67 species of wetland birds, belonging to, 10 orders and 18 families from rural wetland Environs in Panipat district located at a distance of 90 KMs north of Delhi on National Highway No.1 (29.39°N 76.97°E) in Haryana, India. Out of 67 species, 35 species were winter migrants, 18 residents, 10 local migrants and four species were summer migrants. Peculiar species of birds recorded in Panipat rural ponds are Painted Stork Mycteria leucocephala, White-necked Stork Ciconia episcopus, Asian openbill- Stork Anastomusoscitans, Lesser Adjutant Stork Leptoptilos javanicus, Black-necked Stork Ephippiorhynchus asiaticus, Oriental White Ibis Threskiornis melanocephalus, Black Ibis Pseudibis papillosa, Glossy Ibis Plegadis falcinellus, Eurasian Spoonbill Platalea leucorodia, Brahminy Shelduck Tadorna ferruginea, Comb Duck Sarkidiornis melanotos, Tufted Pochard Aythya fuligula and Green Sandpiper Tringa ochropus. On the other hand, familiar species include amongst others, Bar-headed Goose Anser indicus, Common Coot Fulica atra, Northern Shoveller Anas clypeata, Northern Pintail Anas acuta, Common Teal Anas crecca, Common Pochard Aythya ferina, Gadwall Anas strepera and Lesser-whistling Duck Dendrocygna javanica etc. Longest stay during winter season was demonstrated by birds like Northern Shoveller, Northern Pintail, Bar-headed Goose, Greylag Goose and Rudy Shelduck, whereas shortest winter sojourn was observed in case of Mallard, Eurasian Wigeon and Common Pochard. It is interesting to note that migratory birds like Northern Shoveller, Northern Pintail, Common Teal, Bar-headed Goose, Tufted Pochard, and Common Pochard come to Panipat rural ponds from very far off places like Central Russia, Caspian USSR, Siberia, Ladhakh and Central Asia, West and Central Asia and Siberia respectively.

Antibodies to influenza A virus in wild birds across Mongolia, 2006-2009.

Wild waterbirds sampled July 2006-September 2009 in Mongolia were tested for antibodies to avian influenza (AI) virus with the use of a commercially available blocking enzyme-linked immunosorbent assay. Antibodies were detected in 25% (572/2,282) of tested birds representing 26 species, and all antibody-positive samples were from 12 species in the orders Anseriformes and Charadriiformes. The highest antibody prevalence was in Ruddy Shelducks (Tadorna ferruginea; 61.7%; n=261; 95% confidence interval [CI] 55.8-67.6%), Whooper Swans (Cygnus cygnus; 38.4%; n=242; 95% CI 32.3-44.5%), Swan Geese (Anser cygnoides; 15%; n=127; 95% CI 8.6-21.4%), Bar-headed Geese (Anser indicus; 13%; n=738; 95% CI 10.3-15.1%), and Mongolian Gulls (Larus mongolicus; 3.9%; n=255; 95% CI 1.3-6.5%). There was no significant temporal or spatial variation in the presence of antibodies in the sampled species. However, Bar-headed Geese and Mongolian Gulls showed spatial variation in antibody prevalence in 2007 and 2008, respectively. Our study provides insights into the hatch year waterbirds' exposure to AI virus at their natal and molting sites in Mongolia.

TRADITIONAL RURAL WETLANDS IN HARYANA STATE OF INDIA ARE CURRENTLY CONFRONTING MULTICORNERED THREATS LEADING TO EXTINCTION SOONER THAN LATER

The most serious threat to traditional rural ponds in Haryana is associated with transformed societal behavioural patterns, ethics, values and life style, amongst several others. The siltation of ponds with adjoining areas, soil coming in with rain water is a very serious cause of stratification of rural ponds. Also contracting of village community land for sun drying of cow dung cakes inspires villagers to overload periphery of each pond with cow dung turning the premises into grave-yard of dung. This dung is the major source of polluting pond water into blackish water with high load of organic matter. Moreover, it leads to over excessive eutrophication. Building of major highways and connectivity roads have resulted into compartmentalization and degradation of village ponds. Inhabitation of peripheral village ponds boundaries by lower section of society for dwelling purposes is more threat to wetlands. The indifferent inclination of villagers towards silted ponds drenched in bad odour and blackish sludge is the story of 80% of the cases. The total blockage of run-off rainy water towards the natural age old rural ponds due to obstruction by way of human inhabitation has resulted into desertification of shallow water sheet in 90% of the cases. The oblivion of harvesting dried silt in summer for brick making has spelled doom for the ponds turning them into flat ground through successive decades and so on. The water quality in all ponds was overshooting the decaying stage due to the continuous mixing of cow dung drenched rainy water. Over excessive usage of ponds for bathing of cattle, dumping of cow dung and rotten vegetables waste has turned ponds into live sinks of dirt, garbage and rural dairy wastes. Majority of village ponds are now out of existence or in deep black sludge laden or converted into Fish-Farming wetlands. The present studies have indicated that Winter migratory birds like Greylag Goose Anser anser, Bar-headed Goose Anser indicus, Mallard Anas platyrhynchos, Gadwall Anas strepera, Northern Shoveller Anas clypeata, Northern Pintail Anas acuta, Garganey Anas querquedula, Common Teal Anas crecca, Common Pochard Aythya ferina, Tufted Pochard Aythya fuligula, Common Coot Fulica atra, Little Ringed Plover Charadrius dubius, Kentish Plover Charadrius alexandrines, Spotted Redshank Tringa erythropus, Common Redshank Tringa tetanus, Marsh Sandpiper Tringa stagnatilis, Wood Sandpiper Tringa glareola and Pied Avocet Recurivirostra avosetta arrive in the extremely dilapidated rural ponds in Haryana from far off places including Russia, Siberia, China, and Caspian region, east Asia each winter season without any break. As such the extinction of ponds in Haryana directly threatens global avian biodiversity. Keywords: Traditional Rural Wetlands, Perennial Rainy Water, Road Side Puddles, Land Filling, Commercial and Residential Construction, Highway reconstruction

Photolyses of carboxy-hemoglobin of bar-headed goose studied by photoacoustic calorimetry

As a specialized species native to high altitude, bar-headed goose can fly annually over an altitude of 9000m, which means that its hemoglobin has a higher oxygen affinity than its lowland relatives, such as goose and chicken. To study the mechanism of the phenomena, laser ultrasonic calorimetry is used to study dynamic processes associated with photolyses of carboxy hemoglobin (HbCO), including the enthalpy and conformational volume changes, of bar-headed goose and its lowland relatives. Considering the time scales of the reaction lifetimes in the photolyses processes of HbCO, two kinds of piezoelectric transducers, a PVDF film and a PZT ceramic, are used as acoustic signal detectors. For evaluating the relative enthalpy change and the relative conformational volume change in the process, the quantum yield of the photolysis must be taken into account, which has been measured by pump-probe technique. The results show that the enthalpy and conformational volume changes of bar-headed goose are obviously sma...

Power line strikes by Black-necked Cranes and Bar-headed Geese in Tibet Autonomous Region

Power line strikes by Black-necked Cranes and Bar-headed Geese in Tibet Autonomous Region

Insight into Wetland Winter Migratory Avian Biodiversity in Hathnikund Barrage in Haryana State in India

Hathnikund is a place in Yamunanagar District in Haryana where Yamuna Rivers forms a sort of Lake over raised plinth after descending into plains from Himalayas nearby Ponta Sahib town near Haryana-Himachal Border. At the same time, Tajewala Barrage is one more pool like scenic place where waters of Western Yamuna Canal are collected by Govt. of Haryana for subsequent multipurpose. In the present studies, wetland bird’s diversity of Hathnikund has been recorded, analyzed and interpreted. The studies were conducted for a period of three years (September 2005-March 2008) during winter season only. The present studies revealed that in all 47 species of wetland birds belonging to 9 orders and 13 families were observed during September 2005-March 2011. Out of these 47 species of wetland birds, 26 species were Winter Migratory, 13 Resident and 9 species were Local Migratory. In so far as Abundance Status is concerned, 26 species of birds were Common, Nine species were UnCommon, Seven Species of birds were Very Common and five species were Rare. Truely winter migratory birds observed belong to Orders, Ciconiiformes, Anseriformes and Chardriiformes. Prominent migratory birds include, amongst others, Bar-headed Goose Anser indicus, Brahminy Shelduck Tadorna ferruginea, Gadwall Anas strepera, Eurasian Wigeon Anas penelope, Mallard Anas platyrhynchos, Northern Pintail Anas acuta, Northern Shoveller Anas clypeata, Red-crested Pochard Rhodonessa rufina, Common Pochard Aythya ferina, Tufted Pochard Aythya fuligula which come to Hathini Kund during winter from far off places like Russia, Siberia, South and East Asia, China and Caspian region. It is recommended that Hathnikund be further promoted as Winter Halting Place for migratory birds by adding islands within the Water Sheet, the construction of wide margins on the peripheral zones and a rich canopy of endemic trees by implanted in plenty. It is further recommended that Eco-tourism facilities be generated at Hathnikund, linking biodiversity with society’s economic upliftment, employment and awareness. It is also recommended that Fish angling sport can be an added attraction to Bird Watching. In correlation with mystery-wrapped natural ambiences of Hathnikund, it can be sold to tourists of foreign origin thus generating exchange earning facility. As of today, no body known about Hathnikund except amateur bird watchers who turn out to be tourists too, if appropriate lodging boarding facilities are available.DOI: http://dx.doi.org/10.3126/ijls.v5i1.5953 International Journal of Life Sciences Vol.5(1) 2011 39-43

Eco-virological approach for assessing the role of wild birds in the spread of avian influenza H5N1 along the Central Asian Flyway.

A unique pattern of highly pathogenic avian influenza (HPAI) H5N1 outbreaks has emerged along the Central Asia Flyway, where infection of wild birds has been reported with steady frequency since 2005. We assessed the potential for two hosts of HPAI H5N1, the bar-headed goose (Anser indicus) and ruddy shelduck (Tadorna tadorna), to act as agents for virus dispersal along this ‘thoroughfare’. We used an eco-virological approach to compare the migration of 141 birds marked with GPS satellite transmitters during 2005–2010 with: 1) the spatio-temporal patterns of poultry and wild bird outbreaks of HPAI H5N1, and 2) the trajectory of the virus in the outbreak region based on phylogeographic mapping. We found that biweekly utilization distributions (UDs) for 19.2% of bar-headed geese and 46.2% of ruddy shelduck were significantly associated with outbreaks. Ruddy shelduck showed highest correlation with poultry outbreaks owing to their wintering distribution in South Asia, where there is considerable opportunity for HPAI H5N1 spillover from poultry. Both species showed correlation with wild bird outbreaks during the spring migration, suggesting they may be involved in the northward movement of the virus. However, phylogeographic mapping of HPAI H5N1 clades 2.2 and 2.3 did not support dissemination of the virus in a northern direction along the migration corridor. In particular, two subclades (2.2.1 and 2.3.2) moved in a strictly southern direction in contrast to our spatio-temporal analysis of bird migration. Our attempt to reconcile the disciplines of wild bird ecology and HPAI H5N1 virology highlights prospects offered by both approaches as well as their limitations.

Comments on Point:Counterpoint: High altitude is/is not for the birds!

TO THE EDITOR: The debate between Scott et al. (6) and Llanos et al. (4) highlights the remarkable ability of birds and mammals to adapt and survive at high altitudes and cope with reduced oxygen (O2) availability. Scott and colleagues (6) make a compelling argument that birds are far superior to mammals at adapting and thriving in hypoxic environments, both at rest and during exercise. While their argument is supported by comparisons between birds and terrestrial mammals, it ignores marine mammals. Marine mammals such as seals are routinely exposed to and tolerate long bouts of hypoxia during breath-hold diving. For example, elephant seals may dive to depths of nearly 1,600 m and occasionally remain submerged for 2 h (3). Moreover, marine mammals can be exposed to partial pressures of arterial oxygen (PaO2) as low as 12 mmHg during free dives (5), which is less than the 20 mmHg observed in the bar-headed goose (6). Interestingly, a PaO2 of 12 mmHg observed in elephant seals corresponds to arterial saturations and O2 content of only 8% and 2.7 ml O2/dl (5). Thus marine mammals such as the elephant seal demonstrate a remarkable hypoxia tolerance. The integration of several key physiological adaptations including 1) substantially greater myoglobin concentrations compared to other mammals, 2) reductions in metabolism, 3) a greater reliance on aerobic metabolism (i.e., less lactate production), 4) a host of dramatic acute cardiovascular adjustments; and 5) an increased intrinsic cerebral hypoxia tolerance allow marine mammals to thrive in hypoxic environments and enable long deep dives (1–3).

Rebuttal from Llanos et al.

Rebuttal from Llanos et al.

Last Word on Point:Counterpoint: High altitude is/is not for the birds!

to the editor: We would like to thank the scientists who commented on this Point:Counterpoint. We originally argued that high altitude is for the birds because of several unique features that should improve their ability to exercise at extremely high altitudes ([4][1]). Many authors agreed with our

Characterisation of a highly pathogenic H5N1 clade 2.3.2 influenza virus isolated from swans in Shanghai, China

In spring 2009, one strain of H5N1 clade 2.3.2 virus was isolated from wild swans in Shanghai, indicating the importance of the wild swan in the ecology of this highly pathogenic avian influenza virus (HPAIV) in Eastern China. Pathogenicity experiments conducted in this study indicated that the virus was highly pathogenic for chickens but lowly pathogenic for mammalian hosts, as evidenced by reduced infection of mice. The analysis of complete genome sequences and genetic evolution showed that A/Swan/Shanghai/10/09 (SW/SH/09) may be derived from the strain A/silky chicken/Shantou/475/2004 (CK/ST/04), which is homologous to the influenza viruses isolated from chicken, duck, pika, little egret, swan, mandarin duck and bar-headed goose in China Hunan, China Qinghai, Mongolia, Russia, Japan, Korea, Laos and Hong Kong during 2007-2011, indicating that the virus has retro-infected diverse wild birds from chicken, and significant spread of the virus is still ongoing through overlapping migratory flyways. On the basis of the molecular analysis, we also found that there was a deletion of the glycosylation site (NSS) in amino acid 156 of the hemagglutinin (HA) protein when compared with that of the other Clade 2.3.2 viruses isolated between 2007 and 2011. More importantly, the sequence analysis of SW/SH/09 virus displayed the drug-resistant mutations on the matrix protein (M2) and neuraminidase (NA) genes.

The trans-Himalayan flights of bar-headed geese ( Anser indicus )

Birds that fly over mountain barriers must be capable of meeting the increased energetic cost of climbing in low-density air, even though less oxygen may be available to support their metabolism. This challenge is magnified by the reduction in maximum sustained climbing rates in large birds. Bar-headed geese (Anser indicus) make one of the highest and most iconic transmountain migrations in the world. We show that those populations of geese that winter at sea level in India are capable of passing over the Himalayas in 1 d, typically climbing between 4,000 and 6,000 m in 7-8 h. Surprisingly, these birds do not rely on the assistance of upslope tailwinds that usually occur during the day and can support minimum climb rates of 0.8-2.2 km·h(-1), even in the relative stillness of the night. They appear to strategically avoid higher speed winds during the afternoon, thus maximizing safety and control during flight. It would seem, therefore, that bar-headed geese are capable of sustained climbing flight over the passes of the Himalaya under their own aerobic power.