Coastal residence periods and reproductive timing in southern right whales, Eubalaena australis

The duration and timing of coastal residence of individually identified southern right whales at a principal aggregation area on the southern Australian coast differed markedly between females with calves and unaccompanied whales. The mean residence period of females that calved within the aggregation area was 70.9 days, with mean residence mid-points of 20 August in 1993 and 22 August in 1994. In contrast, unaccompanied adults remained resident for an average of only 20.4 days with mean residence mid-points of 27 July and 11 August in 1993 and 1994, respectively. Whales have been sighted at this aggregation area from mid May to late October (approx. 160 days), although the effective calving season (95-100% of calves born) lasted only 88 days in 1993 and 96 days in 1994. The mean birth date based on first sighting with neonatal calf, and corrected for sightability bias, was 15 July in 1993 and 17 July in 1994, with 100% of calves born before 31 August 1993 and 23 September 1994.
The time between birth and dispersal from the aggregation area, at or just prior to the commencement of the southward migration, was highly variable. Calves bom before the mean calving date averaged 80 days within the aggregation area, twice as long as those born after the mean (40 days). The large number of calves estimated to be less than 14 days old at first sighting, combined with the sighting of 26 pregnant females prior to parturition, suggests the majority of births occurred within, or very near to, the aggregation area.     

Shore‐based observations of seasonality,movements, and group behavior of southern right whales in a nonnursery area on the South African west coast

The southern right whale's (Eubalaena australis) demography, occurrence, habitat use, and behavior off South Africa are known predominantly from an ongoing aerial survey data set that started in 1971. The fixed timeframes of these surveys and their geographical bias towards south coast nursery areas have constrained our knowledge about the right whale's seasonal distribution elsewhere. We present shore‐based observations and tracking of right whales at Saldanha Bay on the west coast (2001–2003) that reveal a near year‐round presence and strongly nearshore distribution. With seasonal progression from winter to summer we observed a gradual increase in sighting rate, reduction in swimming speed, less directionality of movement, an increase in group size, and more surface active groups. The area appears to be important for feeding and socializing but not as a calving or nursery area. Individual transits between the south and west coasts, bidirectional alongshore movements, and extended seasonal presence may all be indicative of reoccupation of their former range along the west coast. This is important given the increasing ship traffic at Saldanha Bay, the rapid expansion of the region's oil and gas industry, and the known vulnerability of the closely related North Atlantic right whale (E. glacialis) to ship strikes.     

Is there spatial segregation between reproductive groups of southern right whales along the coastline of southern Brazil?

Santa Catarina State, in southern Brazil, is an important breeding ground for the southern right whale and it is possible to record mother-calf pairs and unaccompanied adults that migrate to this coast to either give birth, mate, or socialize. From the geographical position of the sightings, spatial segregation was evaluated between mother-calf pairs and unaccompanied whales. Using GAM, we analyzed 15 years of aerial survey data from 2003 to 2018. The study area (780 km²) was divided into 500 × 500 m grid cells. Whale count per grid cell was modeled using a set of explanatory variables. The explanatory variables of latitude, coast distance, seabed, and maximum SST were selected for both classes. However, coast type was also selected for unaccompanied whales, while coast linearity and bathymetric slope were additionally selected for mother-calf pairs. The response curves fitted by models indicated a certain degree of spatial segregation, by which mother-calf pairs remained closer to the coast, where the curve peak is reached at 500 m from the coast, compared to unaccompanied whales where the curve peaked near 1,000 m from the coast. Also, unaccompanied whales more frequently appeared in the southern boundaries of the study area, at latitudes south from 28.4°S.     

Numbers, geographic distribution and habitat utilization of waders (Charadrii) in spring on the shores of Iceland

The occurrence of waders m spring (breeding as well as migrating species) in the intertidal zone was studied along the shores of Iceland Ground surveys were made at a total of 115 sites on the west coast in May 1986 and 1987 Repeated counts in the same season were conducted at 76 sites visited m both early and late May 1987 Furthermore, an aerial census covering most of the Icelandic coastline was carried out in May 1990 (76% of the total coastal length of 6650 km and 92% of the total intertidal area of 445 km² were covered from the air) Altogether 345 000 waders were recorded, including 270 000 knot Cahdrts canutus Geographic distribution was uneven, as is the distribution of intertidal areas, with over 85% of all waders occurring on the west coast where >80% of suitable intertidal habitats are found A majority of the knot population, possibly about half of the turnstone Arenaria interpres population and probably only a minority of the sanderling C alba population wintering in the Palearctic and breeding in Greenland/Canada use Iceland as a staging post on their spring passage The local breeding populations of waders and the High Arctic wader populations on passage have rather well separated time schedules for their utilization of intertidal habitats in Iceland Between them the three above-mentioned species of passage migrants show considerable differences m geographic distribution and habitat utilization during the spring staging period m Iceland     

ENVIRONMENTAL FACTORS INFLUENCING THE DISTRIBUTION OF SOUTHERN RIGHT WHALES (EUBALAENA AUSTRALIS) ON THE SOUTH COAST OF SOUTH AFRICA II: WITHIN BAY DISTRIBUTION

Environmental factors are thought to strongly influence the distribution and predictability of the coastal distribution of southern right whales ( Eubalaena australis ) off South Africa. Preferred habitat had generally shallow sloping sedimentary floors and was characteristically protected from open ocean swell and prevalent seasonal winds. This study investigated whether habitat choices at smaller scales (within bays) were similar. Fine scale distribution patterns (GPS) from three years' surveys (1997, 1999, 2000) were analyzed separately within the three main concentration areas St Sebastian Bay, De Hoop, and Walker Bay (containing ∼73% of cow-calf pairs and ∼49% of unaccompanied adults in the whole survey region). Whale density at this scale of within particular bays did not correlate well with predicted variables, but Chi-squared analysis strongly supported results at broader scales, in all bays. Post-hoc "choice" tests between similar areas differing in only one variable revealed that cow-calves preferred (presumed) sandy substrates and especially protection from swell. The strength and predictability of preferences shown at fine scale (where individual movement and weather variability could have great influence) provide strong support for findings at larger scales and emphasize the importance of environmental factors in the habitat choice of wintering right whales.     

Habitat use by southern right whales,Eubalaena australis (Desmoulins, 1822), in their main northernmost calving area in the western South Atlantic

The subtropical and temperate coastal waters of the western South Atlantic are an important calving ground for southern right whales, Eubalaena australis. From 2002 to 2008, data on right whale distribution and habitat characteristics were collected in 14 bays along the coastline of Santa Catarina State, Brazil. Generalized linear models with a negative binomial error distribution were used to determine which environmental (beach morphotype, bay mouth width, bay inclination angle, north‐south and east‐west wind components), and temporal (month and year) variables best explained the aggregation pattern of individuals. Our results suggested that both cow‐calf pairs and adults unaccompanied by calves prefer bays with dissipative beaches, and that cow‐calf pairs apparently avoid bays facing southeast during days of strong east‐west winds. The number of sightings peaked in September and tended to increase over the study period. One particular embayment (Ribanceira beach) had considerably higher numbers of animals and may be considered a preferred spot in this calving ground. Our findings contribute to a better understanding of the species' habitat use and ecological requirements and should be taken into account if new management measures are implemented to further increase protection of southern right whales in the region.     

AERIAL SURVEYS FOR COASTAL DOLPHINS: ABUNDANCE OF HECTOR'S DOLPHINS OFF THE SOUTH ISLAND WEST COAST, NEW ZEALAND

Line-transect surveys of abundance depend critically on the estimation of detection probability, which includes corrections for availability and visibility. In this aerial line-transect survey for Hector's dolphin ( Cephalorhynchus hectori ) we recorded dive times from a helicopter to estimate the proportion of time that dolphins could be seen at or near the water surface and were therefore "available" to be counted. The proportion of available sightings that were counted on transect lines was estimated by comparing sightings by two independent teams of two observers in the fixed-wing plane. The survey covered the area between Farewell Spit and Milford Sound, off the west coast of the South Island of New Zealand. Survey effort was stratified according to existing distribution data. A total of 142 separate sightings was made on 1,355 km of trackline. Average availability for fifty Hector's dolphin groups observed from the helicopter (161 dive/surface cycles) was 46.3% (CV = 4.2%). Data from the two independent observer teams indicated that 96.2% (CV = 2.3%) of the dolphin groups that were at the surface and on the trackline were seen. The abundance estimate for the South Island west coast, corrected for visibility and availability, was 5,388 Hector's dolphins (CV = 20.6%). The total population estimate for South Island Hector's dolphins is 7,270 (CV = 16.2%).     

Foraging range and feeding locations of Shags Phalacrocorax aristotelis during chick rearing

We used radio-tracking techniques to determine the foraging range and feeding locations used by individual Shags Phalacrocorax aristotelis during chick rearing on the Isle of May, Scotland. The mean (±s.d.) foraging range was 7.o±1.9 km (maximum 17 km) and there were no significant sex or year differences. All feeding sites were within 7 km of land. Most (> 90%) were either within 2 km of the colony or in two discrete areas 5–13 km to the north and west. Use of the areas varied between years with both males and females making more use of the north area in 1987 than either 1988 or 1989. Birds used > 11% of the area of sea within the maximum recorded feeding range. This restricted distribution appeared to be related to water-depth and bottom sediment type. Shags fed most frequently in water 21–40 m deep, with a bottom of either gravel and sand, or rock with thin patchy sediment cover.     

Aerial photogrammetry of southern right whales, Eubalaena australis

Between July or August and November 1988 and 1989, 72 cow-calf pairs of right whales ( Eubalaena australis ) were measured photogrammetrically from the air off De Hoop, South Africa. Median coefficients of variation ranged from 1.29 to 4.56%, being lowest in cows and calves for measurements of total length. Fifty-seven adult cows measured from 12.37 to 15.54 m in length, with females photographed for the first time with a calf (= primiparous) being smaller than females that had been seen for the first time with a calf at least five years previously. The lengths of 72 calves ranged from 4.53 to 9.24 m, with those from primiparous females being significantly smaller than calves of multiparous females in every month except July. For 37 calves photographed on more than one occasion the growth rate averaged 2.8±0.7 cm per day, with no significant difference between growth rates of calves from primiparous and from other females, and no significant decrease in growth rate between July/September and September/November. Calves grew from an average of 40% of their mother's length in late July to 51% by mid-October. The size distribution of the adult females was no different from that of 25 adult females landed at South African whaling stations between 1911 and 1963 (after adjustment for possible differences in measurement techniques). Five near-term foetuses recovered in June-August in the same whaling operations also agree closely with the size of calves predicted for 1 August. In a comparison with 17 calves stranded or dying accidentally on the South African coast, most of the accidentally caught animals agreed closely in size with the sample of photogrammetrically measured animals, while most of the stranded animals were equal to or smaller in size than the smallest length interval in the photogrammetrically measured animals. The calves of primiparous females may therefore suffer a higher natural mortality rate than those of multiparous females.     

LONG-RANGE MOVEMENTS OF SOUTH ATLANTIC RIGHT WHALES EUBALAENA AUSTRALIS

Abstract: Movements of southern right whales between Gough Island and South Africa, and between Argentina and Tristan da Cunha, southern Brazil, and South Georgia are documented through matching of six photoidentified individuals. These include the resighting of a male in a mid-oceanic locality some 4,424 km away from (and 11 yr after) its last sighting in a coastal area where it had been seen in six of the preceding eight years, a female photographed in mid-Atlantic resighted with a calf in a coastal nursery area 2,769 km away, resightings of females with calves in different nursery areas 2,051 km apart in different years, and the first example of a link between a coastal nursery area and a feeding ground in high latitudes. The possible implications of these movements for estimates of calving interval and survival rate based on resightings in coastal waters are discussed. The potential for intermingling between populations on either side of the South Atlantic seems greater than was previously considered likely from a comparison of animals photographed in coastal waters.     

ENVIRONMENTAL FACTORS INFLUENCING THE DISTRIBUTION OF SOUTHERN RIGHT WHALES (EUBALAENA AUSTRALIS) ON THE SOUTH COAST OF SOUTH AFRICA I: BROAD SCALE PATTERNS

Aerial surveys over the last 32 yr have shown that the distribution of southern right whales Eubalaena australis along the south coast of South Africa is markedly discontinuous, but highly predictable. A GIS was used at a variety of scales to investigate whether this pattern was related to environmental characteristics. Whale distribution was analyzed as density per 20-min bin of longitude over two temporal and spatial scales, namely 15 bins for 32 yr, and a wider scale but shorter time period, 23 bins for 19 yr, as well as using three years of GPS accuracy data (15 bins) for finer scale analysis. Environmental factors tested were depth, distance from shore, sea floor slope, protection from swell, protection from wind, and shore type. The majority of whales were concentrated in areas that provided reasonable protection from open ocean swell and seasonal winds, and had sedimentary floors with gentle slopes. They generally avoided exposed rocky shorelines. Cow-calf pairs were found significantly closer to shore and in shallower water than unaccompanied whales, particularly off sandy beaches. Habitat choice at this time of year may be related both to energy conservation for calves and lactating females (calm sea conditions) and to protection of the new-born.     

A population estimate of Heaviside's dolphins, Cephalorhynchus heavisidii, at the southern end of their range

Heaviside's dolphins, Cephalorhynchus heavisidii , are endemic to southwestern Africa, where they are exposed to unknown levels of anthropogenic threats, including inshore set netting. Using photo-ID data collected over 3 yr on the west coast of South Africa, we calculated Chapman's-modified Petersen estimates of the number of distinctive individuals at three spatial scales. Sample sizes were small and recapture rates low resulting in high variance. Total population abundance was extrapolated from the proportion of well-marked animals in the population (14%–17%) with between-year estimates adjusted for mortality using data from Commerson's dolphin. The total population size was calculated as 527 animals (CV = 0.35, CI 272–1,020) in the 1999 study area (20 km of coastline, within season), 3,429 animals (CV = 0.36, CI 1,721–6,828) in the central study area (150 km of coastline, 3 yr), and 6,345 animals (CV = 0.26, CI 3,573–11,267) in the full study area (390 km of coastline, 2 yr). Dolphins fitted with satellite transmitters varied in their use of the inshore photographic study area from 39.5% to 94.7% of transmission days (38–51 total). Given the known or suspected biases in the data, these abundance estimates are likely to be biased downward.     

Assessment of the impacts of hydrological fluctuations and salt pans abandonment on Greater flamingos in the Camargue, South of France

Flamingos forage in both commercial salt pans and natural marshes and lagoons along the French Mediterranean coast. In order to assess the impact of changes in management of commercial salt pans and hydrological fluctuations on this flagship species, we evaluated the foraging areas of breeding flamingos using the resightings of 283 breeding flamingos marked with dye at the colony in 1987 and 1989, two years with contrasting hydrological conditions. Teams of observers searched all suitable habitats within 80 km of the colony during the four days following marking and recorded presence of off-duty flamingos. About one-third of the birds were found within 10 km of the colony, but some were seen up to 70 km away. About 24–54% of the birds were found in permanent brackish lagoons and 18–60% in the salt pans, the two most important habitats. In 1989, a dry year with lower water levels in the natural wetlands, the proportion of breeding flamingos using salt pans was twice as high [53%, range (47–60%)] as in 1987 [26%, range (18–29%)], this habitat thus acting as a refuge. Most of the feeding areas shown to be important for flamingos breeding in the Camargue are thus susceptible to variations according to rainfall and to transformations or drying out if the salt pans are abandoned. Our results provide essential benchmarks to reconsider the conservation of this flagship species when management of commercial salt pans changes.     

LONG-TERM TRENDS IN ABUNDANCE AND DISTRIBUTION OF MANATEES (TRICHECHUS MANATUS) IN THE NORTHERN BANANA RIVER, BREVARD COUNTY, FLORIDA

Four aerial survey projects were conducted between 1977 and 1986 to determine the abundance, density and distribution of West Indian manatees (Trichechus manatus), in the northern Banana River, Kennedy Space Center, Florida. Manatee density and distribution within selected portions of the 78.5 km² study area were determined. Peak numbers of manatees occurred in spring of each year. The maximum counts increased from 56 in 1978 to 297 in 1986. Manatee abundance was lowest in the winter of each year. Mean density per flight increased from 0.52 manatees/km2 in 1977–78 to 2.73/km² in 1984–86. This increase may reflect increases in the east coast population or shifts in the population distribution. Distributional changes were observed in the study area through time, with a lower percentage of manatees occurring in industrial areas and a correspondingly higher percentage of manatees in nonindustrial areas by 1985.     

Southern Hemisphere humpback whales wintering off Central America: insights from water temperature into the longest mammalian migration

We report on a wintering area off the Pacific coast of Central America for humpback whales (Megaptera novaeangliae) migrating from feeding areas off Antarctica. We document seven individuals, including a mother/calf pair, that made this migration (approx. 8300km), the longest movement undertaken by any mammal. Whales were observed as far north as 11 degrees N off Costa Rica, in an area also used by a boreal population during the opposite winter season, resulting in unique spatial overlap between Northern and Southern Hemisphere populations. The occurrence of such a northerly wintering area is coincident with the development of an equatorial tongue of cold water in the eastern South Pacific, a pattern that is repeated in the eastern South Atlantic. A survey of location and water temperature at the wintering areas worldwide indicates that they are found in warm waters (21.1-28.3 degrees C), irrespective of latitude. We contend that while availability of suitable reproductive habitat in the wintering areas is important at the fine scale, water temperature influences whale distribution at the basin scale. Calf development in warm water may lead to larger adult size and increased reproductive success, a strategy that supports the energy conservation hypothesis as a reason for migration.     

Evidence for a widely expanded humpback whale calving range along the Western Australian coast

The recognized calving grounds of humpback whales (Megaptera novaeangliae) that breed along the Western Australian coast (Breeding Stock D) extend along the Kimberley coast between Camden Sound and Broome (15°–18°S). However, there are reports of neonates further south, suggesting that the calving areas may be poorly defined. During aerial photogrammetric research in 2013 and 2015, we sighted large numbers of humpback whale calves along North West Cape (21°47′–22°43′S). We estimated the minimum relative calf abundance to be 463–603 in 2013 and 557–725 in 2015. We categorized the calves as either neonate or post neonate according to their color and size. The majority of calves sighted in both years (85% in 2013; 94% in 2015) were neonates. Our observations indicate that a minimum of approximately 20% (17.1%–24.3%) of the expected number of calves of this population are born near, or south of, North West Cape. We thus demonstrate that the calving grounds for the Breeding Stock D population extend south from Camden Sound in the Kimberley (15°S) to at least North West Cape (22°43′S), 1,000 km southwest of the currently recognized calving area.     

Heterozostera tasmanica (Martens ex aschers.) den Hartog in Chile

A 1.2 km² meadow of Heterozostera tasmanica (Martens ex Aschers.) den Hartog was found at Pto. Aldea, Bahia Tongoy, 60 km south of Coquimbo, 30°S on the coast of Chile. This provides documented evidence of seagrass occurrence on the west coast of South America. Since H. tasmanica is widespread throughout southern Australia, the Chilean stock represents a highly disjunct population. It appears from several growth parameters (density, leaf biomass, leaf area index, specific leaf area, δ ¹³C) that the H. tasmanica meadow at Pto. Aldea is very similar to those found in other parts of the world.     

Changes in North Atlantic right whale (Eubalaena glacialis) cow–calf association times and use of the calving ground: 1993–2005

Like most mysticetes, North Atlantic right whale cows generally separate from their calves on their feeding grounds within a year. Right whale life history data from 1993 to 2005 were analyzed to determine the duration of cow/calf associations and where the pair separated. A change occurred with the 2001 cows; 71% of those available stayed with their calves into the second year and this behavior remained elevated for several years. Less experienced cows, independent of their age, were more likely to extend their associations. The occurrence of cow/yearling associations was not related to the length of the cow's previous interbirth interval, used as a proxy for cow condition, but the hypothesis that body condition impacts how long cows nurse their young could not be adequately tested. Seventy-seven percent of the observed cow/yearling pairs also returned to the calving ground, a substantial physiological investment given the 1,450 km plus migration and the fact that they fast there, indicating that factors other than nutrition also influenced the cow's behavior. The concurrent increase in juveniles in the shallow waters of the winter calving grounds may afford naive whales greater protection from predators or provide a social benefit that improves their overall fitness.     

Distribution of Hector's dolphin (Cephalorhynchus hectori) off the west coast,South Island,New Zealand,with implications for the management of bycatch

To support decision making on placement of protected areas for Hector's dolphin on New Zealand's South Island west coast, we conducted three aerial surveys documenting the species’ distribution in this area. The first survey was designed to quantify alongshore distribution and abundance, and revealed a patchy distribution with a central zone of high density. Two further surveys, in summer and winter, focused on this central zone to quantify offshore distribution in detail. Dolphin density decreased with increasing distance offshore, with no dolphins sighted more than 6 nmi from the coast or in water deeper than 60 m. There was no significant difference in offshore distribution between summer and winter surveys conducted in 2003 (G= 2.15, df = 5, P= 0.83). Partial Mantel tests showed that dolphin distribution was best explained by distance from the coast, in both summer (r_M= 0.088, P= 0.0001) and winter (r_M= 0.054, P= 0.0004). Spatial contouring techniques showed that small (ca. 5 km) and medium scale (ca. 50 km) patterns of density in the central zone were remarkably consistent, suggesting year‐round residency. Based on these data, the current restrictions on commercial gillnetting protect 60% or less of the dolphin population for 3 mo of the year.