Swimming Birds Research Articles

Long monitoring of Birds of Elssuki Area. Sinnar State, Sudan

This study aims to make a database of the birds in the area of Elssuki, Sinnar state - Sudan. The period of study spanning from 2008 to 2023 with a mix of methods used to identify bird species in many sites in the locality, these methods include road count, line transects, and direct count besides registering every strange, rare, or unusual single species seen in the area. All these methods are used by different researchers and applied in such studies in Sudan. The study revealed that the area is one of the important areas enriched of birds in Sinnar state of 19 orders 53 families. The total number of species is 129 species. It included all birds; water birds, tree birds, diving birds, dabbling birds, swimming birds, small waders, and passerines which the most. The study concluded that there is a need for comprehensive and regular studies and short and long-term monitoring to identify, classify, and establish a database for Sudan Birds Atlas.

Impact of coastal island restoration engineering and subsequent tourism on migratory waterbirds: a 3‐year case from Southern China

Coastal engineering poses a significant threat to the survival of migratory waterbirds worldwide. However, the mechanisms through which engineering affects waterbirds are still unclear. To gain a better understanding of this issue, we conducted a three‐year survey of waterbirds on Shanxinsha Island, which underwent restoration engineering, along the East Asian–Australasian Flyway. We compared the seasonal migratory change among different species groups through and after the island restoration engineering. We observed a total monthly maximum count of 118,506 individuals from 61 waterbird species over the span of 38 months, including eight globally threatened species and five species that exceeded 1% of the flyway population. Throughout the survey periods, the average number of total waterbirds and small shorebirds observed during the migrating season decreased by 52.7 and 48.6%, respectively. The massive loss of high‐tide roosting areas was the primary factor contributing to this decline. The combined effects of increased vegetation and deeper water levels resulted in a 38.8% reduction in exposed tidal flat area, as determined through land cover verification and fractional vegetation cover calculations. While tourism activities exhibited fewer negative consequences compared to island restoration engineering, they had a greater impact on small breeding shorebirds. Our study showed that small shorebirds were particularly susceptible to island restoration engineering, whereas large shorebirds and swimming birds were more flexible in their use of roosting or foraging sites. We suggest that the impact of future coastal engineering requires more detailed assessment and monitoring, especially for small migratory shorebirds.

Annual Dynamics of Bird Community at a Coastal Wetland and Their Relation to Habitat Types: The Example of Beidagang Wetland, Northern China

In order to provide more scientific guidance for wetland bird protection, this study addressed the dynamics of the bird community sorted by ecotypes, classifications and threat categories from 2015 to 2019, and non-metric multidimensional scaling analysis, generalized additive models and the Mantel test were used to examine the relationships between bird communities and habitat types. The results showed that: (1) The abundance of birds peaked in 2017 at 88,258 individuals and then declined. Moreover, there was an inverse trend between species richness and abundance of birds, meaning greater abundance is associated with fewer species. (2) Swimming birds were dominant ecotypes and Anseriformes possessed the highest abundance. It was noteworthy that the abundance of critically endangered birds (Aythya baeri and Grus leucogeranus) and the species richness of endangered birds increased. (3) Building land and farmland had dominant impacts on the composition of bird community. Wading birds and birds in Gruiformes were significantly impacted by building land and farmland, and near threatened species were substantially influenced by farmland. Therefore, maintaining good connectivity between protected areas and surrounding areas is one of the best ways to effectively manage biodiversity of the target area. This research may provide a broader insight for coastal wetland bird habitat management and bird diversity preservation.

Mesolithic Hunters and Fishermen of Nadporizhzhia on the Materials of Ihren 8 Site

The famous Mesolithic settlement Ihren 8 in Central Ukraine on the bank of the Dnipro River was excavated by D. Telehin, L. Zalizniak, D. Nuzhnyi in 1973—1976, 1978, 1982, 1986, 1988, 1990. The settlement consisted of 10 large deepened into the ground dwellings located along the river bank. The remains of dwellings looked like the rounded-shaped lenses of dark sand of 6,0—9,0 m in diameter and filling of 0,5—1,0 m thick. Most of them had been partly destroyed by the river. Inside the dwellings there were a lot of microlithic flint artefacts, bone tools and bones of animals (auroch, red deer, elk, horse, boar, fox, wolf, hare), swimming birds, fish and cockleshells. Flint and bone artifacts from Ihren 8 are typical for Kukrek Mesolithic culture of South Ukraine. For microlithic flint industry of the site a perfect micro-blade technique, pencil-shaped pressure flaking cores, numerous round-shaped scrapers, flake burins and Kukrek-type insets are typical. Among bone tools there are typical spearheads with slots for microblade insets. There were also found numerous points, awls, borers, adzes and arrowheads made of cracked bird bones. Several tools have the geometric ornament on surface. The site is dated by Boreal period of Holocene due to the radiocarbon dating (8th ka BCE). The deepened dwellings of the Mesolithic settlement Ihren 8 have the analogies in dwelling structures of other Mesolithic sites (for example, Viazivok 4A site in Poltava Region in Ukraine, Jasztelek site in Hungary) and also in winter semi-dugouts of Siberian people well-known under name “ground tent” or “golomo”. Obviously Ihren 8 dwellings were round in section, deepened into the ground up to 1,0 m, with conical wooden frame covered with reed and turf. According to archaeological and ethnography parallels such large deepened dwellings used as the winter dwellings for several small families of hunters and fishermen of the Dnipro River valley. During the warm seasons small families moved to the individual light dwellings on the river bank.

Foot-propelled swimming kinematics and turning strategies in common loons.

Loons (Gaviiformes) are arguably one of the most successful groups of swimming birds. As specialist foot-propelled swimmers, loons are capable of diving up to 70 m, remaining underwater for several minutes, and capturing fish. Despite the swimming prowess of loons, their undomesticated nature has prevented prior quantitative analysis. Our study used high-speed underwater cameras to film healthy common loons (Gavia immer) at the Tufts Wildlife Clinic in order to analyze their swimming and turning strategies. Loons swim by synchronously paddling their feet laterally at an average of 1.8 Hz. Combining flexion-extension of the ankle with rotation at the knee, loon swimming resembles grebe swimming and likely generates lift forces for propulsion. Loons modulate swimming speed by altering power stroke duration and use head bobbing to enhance underwater vision. We observed that loons execute tight but slow turns compared with other aquatic swimmers, potentially associated with hunting by flushing fish from refuges at short range. To execute turns, loons use several strategies. Loons increase the force produced on the outside of the turn by increasing the speed of the outboard foot, which also begins its power stroke before the inboard foot. During turns, loons bank their body away from the turn and alter the motion of the feet to maintain the turn. Our findings demonstrate that foot-propelled swimming has evolved convergently in loons and grebes, but divergently from cormorants. The swimming and turning strategies used by loons that allow them to capture fish could inspire robotic designs or novel paddling techniques.

Distribution and ways of dispersion of American rotifer Kellicottia bostoniensis (Rousselet, 1908) (Rotifera: Brachionidae) in waterbodies of European Russia

In the first decade of the 21th century, the findings of a new invader, the American rotifer, Kellicottia bostoniensis (Rousselet, 1908), has become more frequent in Russia. By 2015 K. bostoniensis had been detected in more than 40 different waterbodies and watercourses of European part of Russia. American rotifer is a widely spread and common species in forest lakes and rivers of the Baltic Sea basin, Volga-Baltic watershed; in the Volga River basin it has spread southward to 55° N (lakes of the Oka and Pra rivers) and eastward to 45° E (the Kerzhenets River, Cheboksary Reservoir basin). The rotifers inhabit small ( 200 km2), shallow ( 20 m) waterbodies with a trophy range from oligo- to eutrophy. In Russia K. bostoniensis occurs in a wide range of color of water (30–680 degrees Pt–Co-scale) compared to waterbodies of Western Europe. The rotifer is tolerant to temperature regime and oxygen concentrations in water. In the hypolimnion of stratified lakes, K. bostoniensis reaches high abundance (>100000 ind./m3) at a very low concentration of dissolved oxygen (2.5 mg/L or about 20% of saturation) and water temperature of 5–12°С. The invader and aboriginal species K. longispina coexisted in deep lakes and deep parts of reservoirs (the depth more than 5 m); in shallow lakes only K. bostoniensis was found. On the contrary, in most parts of large reservoirs of the Upper Volga only K. longispina was recorded. The possibility and the direction of transfer of the rotifer by swimming birds are discussed.

Functional correlation between habitat use and leg morphology in birds (Aves)

Many of the morphological features of animals are considered to be adaptations to the habitat that the animals utilize. The habitats utilized by birds vary, perhaps more than for any other group of vertebrates. Here, we study possible adaptations in the morphology of the skeletal elements of the hind limbs to the habitat of birds. Measurements of the lengths of the femur, tibiotarsus and tarsometatarsus of 323 bird species from 74 families are used together with body mass data, taken from the literature. The species are separated into six habitat groups on the basis of literature data on leg use. A discriminant analysis of the groups based on leg morphology shows that swimming birds, wading birds and ground living species are more easily identified than other birds. Furthermore, functional predictions are made for each group based on ecological and mechanical considerations. The groups were tested for deviation from the norm for all birds for three indices of size- and leg-length-independent measures of the bones and for a size-independent-index of leg length. Several of the groups deviate significantly from the norm for one or more of the indices used, suggesting habitat-related adaptations in the leg morphology of birds. The results indicate that stability is an important factor affecting the leg morphology of primarily long-legged birds. The femur seems to be more important than previously thought because several of the groups have high femur indices, suggesting a positive selection pressure on this bone. On a general basis, the results suggest that the effect of leg length should be taken into consideration when discussing adaptations of mass-independent lengths of the long bones of the legs of birds (Less)

Delta-wing function of webbed feet gives hydrodynamic lift for swimming propulsion in birds.

Most foot-propelled swimming birds sweep their webbed feet backwards in a curved path that lies in a plane aligned with the swimming direction. When the foot passes the most outward position, near the beginning of the power stroke, a tangent to the foot trajectory is parallel with the line of swimming and the foot web is perpendicular to it. But later in the stroke the foot takes an increasingly transverse direction, swinging towards the longitudinal axis of the body. Here we show that, early in the power stroke, propulsion is achieved mostly by hydrodynamic drag on the foot, whereas there is a gradual transition into lift-based propulsion later in the stroke. At the shift to lift mode, the attached vortices of the drag-based phase turn into a starting vortex, shed at the trailing edge, and into spiralling leading-edge vortices along the sides of the foot. Because of their delta shape, webbed feet can generate propulsive forces continuously through two successive modes, from drag at the beginning of the stroke, all the way through the transition to predominantly lift later in the stroke.

Kinematic parameters of terrestrial locomotion in cursorial (ratites), swimming (ducks), and striding birds (quail and guinea fowl)

The importance of size, functional features and morphological features in adaptation for walking in birds were studied. The time and space kinematic parameters of locomotion were compared in two running birds, the ratites (rhea, kiwi, Paleognatiforms), in two swimming birds, (ducks) and two striding birds, (quail and Guinea fowl). The results showed that in the two phases, stance and swing, the time and space parameters worked in opposite ways: the duration of the swing was constant, but its length increased with speed. In contrast, the duration of the stance was correlated to speed, while its length was not (except in ducks). In all the birds, a higher speed was achieved by a decrease of the stance duration, and an increase of the swing length. The kinematic parameters were not used in the same way in all species: There is a size effect and large birds increase their speed mainly by increasing the frequency of their movements and the small species increase mainly their amplitude. Nevertheless, it is not the main factor and morphology, such as swimming adaptation features of the ducks, and behaviour, are important because they modify the mechanical constraints and influence the kinematics parameters.

Hydrodynamic drag of diving birds: effects of body size, body shape and feathers at steady speeds.

For birds diving to depths where pressure has mostly reduced the buoyancy of air spaces, hydrodynamic drag is the main mechanical cost of steady swimming. Drag is strongly affected by body size and shape, so such differences among species should affect energy costs. Because flow around the body is complicated by the roughness and vibration of feathers, feathers must be considered in evaluating the effects of size and shape on drag. We investigated the effects of size, shape and feathers on the drag of avian divers ranging from wing-propelled auklets weighing 75 g to foot-propelled eiders weighing up to 2060 g. Laser scanning of body surfaces yielded digitized shapes that were averaged over several specimens per species and then used by a milling machine to cut foam models. These models were fitted with casts of the bill area, and their drag was compared with that of frozen specimens. Because of the roughness and vibration of the feathers, the drag of the frozen birds was 2-6 times that of the models. Plots of drag coefficient (C(D)) versus Reynolds number (Re) differed between the model and the frozen birds, with the pattern of difference varying with body shape. Thus, the drag of cast models or similar featherless shapes can differ both quantitatively and qualitatively from that of real birds. On the basis of a new towing method with no posts or stings that alter flow or angles of attack, the dimensionless C(D)/Re curves differed among a size gradient of five auklet species (75-100g) with similar shapes. Thus, extrapolation of C(D)/Re curves among related species must be performed with caution. At lower speeds, the C(D) at a given Re was generally higher for long-necked birds that swim with their neck extended (cormorants, grebes, some ducks) than for birds that swim with their head retracted (penguins, alcids), but this trend was reversed at high speeds. Because swimming birds actually travel at a range of instantaneous speeds during oscillatory strokes, species variations in drag at different speeds must be considered in the context of accelerational stroking.

Daily Energy Expenditure of Tufted Ducks: A Comparison Between Indirect Calorimetry, Doubly Labelled Water and Heart Rate

1. The doubly labelled water (DLW) technique has been used to estimate the rate of energy expenditure of many species of free-living birds including some that dive. The technique, however, has never been validated in an actively diving bird. 2. DLW was used to estimate the metabolic rate of the diving tufted duck and the derived estimate was compared with the value obtained by direct respirometry. All the equations used to calculate the energy expenditure from DLW produced estimates for individual birds with large ranges of errors. Even the most accurate equation, S4 (Speakman 1993), underestimated oxygen consumption by an average of 15.6%. The range of errors for that equation (− 83 to + 67%) shows that in the diving tufted duck, the DLW technique has a reduced precision3. This reduced precision is probably due to the high water flux measured. As a high water turnover is likely to be a consistent feature of many diving and swimming birds and mammals, care should be exercised in interpreting measurements derived from DLW for these animals4. Heart rate, used as another indicator of metabolic rate, was also monitored in four of the birds. Although there was again a wide range of individual errors (− 38 to + 71%), the mean estimate was not significantly different from those derived from DLW and direct respirometry

Bird-habitat relationships in a Texas estuarine marsh during summer

Birds were surveyed during summer 1985 in five adjacent saline vegetation zones and during summers 1986 and 1991 in 6 adjacent vegetation zones on the San Bernard National Wildlife Refuge on the upper Texas Coast. Although 66 bird species were recorded, numbers and species varied among years, and only 17 were nesting species. A few bird species used all vegetation types at some time, but most were limited by vegetation structure or water presence. Olney’s three-square bulrush (Scirpus olneyi), saltgrass (Distichlis spicata), and mudflats were especially favored feeding and resting areas in response to periodic flooding and had the greatest frequency of use as well as species richness. Reduced rainfall and water depths during 1986 were reflected in a change toward birds favoring drier conditions. Heavy rainfall in 1991 decreased diversity but increased usage and favored freshwater and swimming birds. Although tidally influenced wetlands often are considered uniform, dynamic water and salinity regimes observed along this coast must be considered in the design of any management or conservation program.

Swimming by sea otters: adaptations for low energetic cost locomotion

The energetics and hydrodynamics of surface and submerged swimming were compared in the sea otter (Enhydra lutris). 1. Sea otters used two distinct speed ranges that varied with swimming mode. Sustained surface swimming was limited to speeds less than 0.80 m/s, while sustained submerged swimming occurred over the range of 0.60 to 1.39 m/s. 2. Rates of oxygen consumption (VO2) at the transition speed (0.80 m/s) were 41% lower for submerged swimming by sea otters in comparison to surface swimming. 3. Total cost of transport for surface swimming sea otters, 12.56 joules/kg.m, was more than 12 times the predicted value for a similarly-sized salmonid fish. Transport costs for submerged swimming at the same speed was only 7.33 times the predicted value. 4. The allometric relationship for minimum cost of transport in surface swimming birds and mammals was y = 23.87 chi -0.15 where y = cost of transport in joules/kg.m and x = body mass in kg. This regression loosely parallels the relationship for salmonid fish. 5. Correlations between aquatic behavior, morphological specialization, and swimming energetics indicate that the development of swimming in mustelids involved transitions from fore-paw to hind-paw propulsion, and from surface to submerged swimming.

FEEDING ECOLOGY OF PISCIVOROUS BIRDS AT LAKE ST LUCIA, PART 3: SWIMMING BIRDS

Summary Whitfield, A. K. & Blaber, S. J. M. 1978. Feeding ecology of piscivorous birds at Lake St Lucia, Part 3: Swimming birds. Ostrich 50:10-20. The diets, foraging periodicities and feeding behaviour of the Reed Cormorant Phalacrocorax africanus, Whitebreasted Cormorant Phalacrocorax carbo and White Pelican Pelecanus onocrotalus were studied at Lake St Lucia, Natal, South Africa, during 1975 and 1976. The Reed Cormorant fishes in shallow water within 100 m of the shore and mainly caught Sarotherodon mossambicus and Solea bleekeri, while the Whitebreasted Cormorant caught Mugilidae, Rhabdosargus sarba and Thryssa vitrirostris in deeper water. The diet of the White Pelican followed three distinct phases: a pre-incubation phase when the birds followed and preyed heavily on migrating Mugil cephalus shoals; an incubation and post-incubation phase when the adults flew a round trip of 200 km to the north to obtain freshwater fish, mainly cichlids, from the Pongolo pans where fishes were concentrated and densi...

V.—Observations on the Body Temperature of some Diving and Swimming Birds

SUMMARYObservations were made on the body temperature of a large number of diving and swimming birds of eighteen different species in the Orkney Islands and Firth of Forth, Scotland, and on and around Cayuga Lake, N.Y., U.S.A., immediately after they were killed by shooting.1. In all the species examined, where the sex was determined, it was found that the rectal temperature of the male was slightly below that of the female.2. Of the orders examined the highest temperatures were found in the Longipennes and the lowest in the Tubinares. When arranged according to body temperature the series does not run parallel with the zoological series.In conclusion, I wish to express my indebtedness to Dr H. D. Reed and Dr A. H. Wright for help in identifying the specimens obtained from Cayuga Lake and the surrounding district.