scholarly journals Photo-Identification Methods Reveal Seasonal and Long-Term Site-Fidelity of Risso’s Dolphins (<i>Grampus griseus</i>) in Shallow Waters (Cardigan Bay, Wales)

2013 ◽  
Vol 03 (02) ◽  
pp. 66-75 ◽  
Author(s):  
Marijke N. de Boer ◽  
Josephine Clark ◽  
Mardik F. Leopold ◽  
Mark P. Simmonds ◽  
Peter J. H. Reijnders
Keyword(s):  
Site Fidelity ◽  
Shallow Waters ◽  
Identification Methods ◽  
Photo Identification ◽  
Grampus Griseus

scholarly journals Long-term site fidelity and residency patterns of bottlenose dolphins (Tursiops truncatus) in the Tramandaí Estuary, southern Brazil

10.5597/00224 ◽  
2017 ◽  
Vol 11 (1-2) ◽  
pp. 155-161 ◽  
Author(s):  
Amanda Baron Di Giacomo ◽  
Paulo Henrique Ott
Keyword(s):  
Tursiops Truncatus ◽  
Site Fidelity ◽  
Bottlenose Dolphins ◽  
Southern Brazil ◽  
Local Conservation ◽  
Entire Study ◽  
Photo Identification ◽  
Average Observation ◽  
Number Of Individuals

The occurrence of common bottlenose dolphins (Tursiops truncatus) in Tramandaí Estuary, southern Brazil, is described based on a photo-identification study conducted between January 2009 and February 2010. A total of 128 survey days were conducted with an average observation effort of 2.6 hours per day (SD = 0.6). Approximately 2050 photographs were taken from a shore land location at the mouth of the estuary. A total of nine dolphins were identified, including three calves. The dolphins were observed during all seasons, with a greater frequency during fall (79.3% of the days) and winter (60.7% of the days). The summer presented the lowest occurrence (2.4% of the days) of dolphins. During the entire study period, the maximum number of individuals sighted in any given day ranged from one to seven (average = 2.8 dolphins; SD = 1.35; n = 51). The residence indices, based on the resighting frequency of dolphins during the study period, ranged from 0.02 to 0.24 (average = 0.13; SD = 0.08; n = 9). However, most of the animals (67%) were resighted in over five months during a year and could be classified as residents. Longterm site fidelity was detected by resightings of four dolphins for over 18 years. These data combined reinforce the importance of the Tramandaí Estuary for the common bottlenose dolphins in the region and highlight the need for local conservation efforts to guarantee the long-term persistence of these coastal populations.

Insights on site fidelity and calving intervals of the marine tucuxi dolphin (Sotalia fluviatilis) in south-eastern Brazil

2001 ◽  
Vol 81 (6) ◽  
pp. 1049-1052 ◽  
Author(s):  
Marcos César de Oliveira Santos ◽  
Luciana Barão Acuña ◽  
Sergio Rosso
Keyword(s):  
Small Area ◽  
Site Fidelity ◽  
Photo Identification ◽  
South Eastern ◽  
Eastern Brazil ◽  
Ecological Aspects ◽  
Sotalia Fluviatilis ◽  
Calving Intervals ◽  
Long Term Studies

Ecological aspects of the marine tucuxi dolphin, Sotalia fluviatilis (Cetacea: Delphinidae), remain poorly known. Important information can be gathered in long-term studies using photo-identification. Using this methodology, the authors present the first evidence of site fidelity for marine tucuxis in the Cananéia Estuary (25°03′S 48°01′ W), south-eastern Brazil. A total of 86 easily recognizable individuals was catalogued from June 1996 to August 2001, but most of them have been sighted from May 2000. From June 1997 to August 2001, three female tucuxis were sighted on nine (KN #19), 22 (KN #30) and 28 (KN #10) different days in a relatively small area (∼16 km2). Each of them was observed with a calf in 1997–1998 and again with a new offspring in 2000–2001. Thirteen other individuals were reported on eight to 19 different days in the same area between May 2000 and August 2001. Our observations lead to conclusions on the evidence of site fidelity and indicate that calving intervals may range between two and three years for this species in the surveyed area.

Pupping-site fidelity among individual Steller sea lions (Eumetopias jubatus) at Chiswell Island, Alaska

2008 ◽  
Vol 86 (8) ◽  
pp. 826-833 ◽  
Author(s):  
P. Parker ◽  
J. T. Harvey ◽  
J. M. Maniscalco ◽  
S. Atkinson
Keyword(s):  
Site Fidelity ◽  
Surf Zone ◽  
Gulf Of Alaska ◽  
Eumetopias Jubatus ◽  
Steller Sea Lions ◽  
Sea Lions ◽  
Photo Identification ◽  
Pup Survival ◽  
Breeding Seasons

Pupping-site fidelity (defined as pupping within 5.8 m of a previous location in ≥2 years) in Steller sea lions ( Eumetopias jubatus (Schreber, 1776)) was investigated during the breeding seasons from 2001 to 2005 at Chiswell Island, a small rookery in the Gulf of Alaska. Density of females was minimal with 54–80 pups born. Photo-identification of individuals and GPS points, including elevation of the rookery, were used to determine locations of 297 births. Sixty-four percentage (35/55) of the females exhibited pupping-site fidelity, and mean frequency of site fidelity was greater for females that gave birth >3 times. Fifty percentage of the births occurred at 22% of the locations for all years, indicating that multiple births occurred at some locations throughout the breeding season. Competition or aggression among females for specific pupping locations before birth was not observed, and there was no temporal order of pupping locations used, indicating that the rookery was not overcrowded and that many suitable pupping locations existed. Multiparous females gave birth at significantly greater distances from the surf zone than primiparous females. Long-term monitoring of pupping-site fidelity in combination with other measures of maternal care will ultimately determine which factors have the greatest effect on pup survival.

scholarly journals Risso's dolphins (Grampus griseus) in a proposed Marine Protected Area off east Lewis (Scotland, UK), 2010–2017

2019 ◽  
Vol 99 (3) ◽  
pp. 703-714
Author(s):  
Caroline R. Weir ◽  
Nicola K. Hodgins ◽  
Sarah J. Dolman ◽  
Alice E. M. Walters
Keyword(s):  
Population Size ◽  
Coastal Waters ◽  
Protected Area ◽  
Site Fidelity ◽  
Marine Protected Area ◽  
Beaufort Sea ◽  
Photo Identification ◽  
Grampus Griseus ◽  
Water Depths ◽  
Ongoing Monitoring

AbstractThe coastal waters of east Lewis from the Butt of Lewis to Loch Erisort are a proposed Marine Protected Area (MPA) for Risso's dolphins (Grampus griseus). A total of 100.4 h (2006.4 km) of active search effort (Beaufort sea states ≤3) was collected during 72 dedicated boat surveys between 2010 and 2017 (primarily in August and September) in the southern part of the MPA and south to the Shiant Isles. Forty Risso's dolphin sightings and 24.1 h of encounter effort were recorded, predominantly along the southern and eastern Eye Peninsula in 20–40 m water depths and at distances <1 km from shore. Group size ranged from one to 50 animals (mean = 11.8 dolphins) and calves occurred in 37.5% of sightings. A total of 2404 shore-based scans (Beaufort sea states ≤3) carried out from Tiumpan Head between September 2011 and December 2017 resulted in 271 (11.3%) ‘dolphin-present’ scans. Dolphins were present year-round, with a seasonal increase between May and October. ‘Calf-present’ scans only occurred between April and October. Photo-identification images from 28 boat surveys produced a minimum population size of 117 animals. There was evidence of high inter- and intra-annual site fidelity, with individual dolphins photographically captured in up to six of the eight survey years, and between two and seven capture dates being recorded for over 45% of individuals within most years. The combined datasets support the importance of east Lewis for Risso's dolphins, and recommendations are made for ongoing monitoring of dolphin occurrence throughout the wider MPA.

scholarly journals Calving rates, long-range movements and site fidelity of southern right whales (Eubalaena australis) in south-eastern Australia

2021 ◽  
Vol 22 (1) ◽  
pp. 17-28
Author(s):  
Mandy Watson ◽  
Kasey Stamation ◽  
Claire Charlton
Keyword(s):  
Long Range ◽  
Site Fidelity ◽  
The South ◽  
Australian Population ◽  
Photo Identification ◽  
South Eastern ◽  
Eastern Australia ◽  
Right Whales ◽  
Southern Right Whales

Within New Zealand and eastern Australia, over 58,000 southern right whales were harvested by commercial whalers between 1790 and 1980, with approximately 19,000 harvested from south-eastern Australia. Local extirpation is believed to have led to a loss of cultural memory of calving areas, contributing to the limited recovery of the south-eastern Australian population. While the number of whales observed using the south-eastern Australian coastline is increasing, there has been no change over three decades in the annual abundance of cow-calf pairs at Logans Beach in Warrnambool, Victoria, the only established calving ground in the region. Knowledge of life history parameters of the south-eastern Australian population is lacking. Here, we examine sightings and photo-identification data from southern Australia to investigate calving intervals, long range movements and fidelity to the Logans Beach nursery ground. Sightings data revealed at least 93 calves were born at Logans Beach between 1980 and 2018 (an average of 2.6 per year) with a mean calving interval of 3.5 ± 1.0 years (± SE, n = 34). Comparison between photo-identification catalogues compiled for south-eastern and south-western Australian populations shows that southern right whales are wide ranging within southern Australian waters. Females can be sighted at locations as far apart as 3,800 km across seasons and there is overlap in the wintering range of the south-eastern and south-western populations, with at least 7% of whales using both regions. We also provide the first report of an Australian southern right whale female with strong site fidelity to a calving area in one region relocating long-term to a calving area in another region. This work highlights several knowledge gaps, such as; the location of feeding and conception grounds for this population as well as the degree of mixing between the two Australian populations outside their wintering areas. In addition, the proportion of female calves born at Logans Beach returning to their natal site to calve remains unclear. Our work provides the first assessment of calving rates, movement and site fidelity within the south-eastern Australian population, critical for understanding constraints to recovery and informing conservation management of southern right whales in Australia. Targeted, long-term monitoring programs across the south-eastern Australian region are needed to provide demographic information on which to base predictions of the impacts of anthropogenic threats such as noise disturbance, entanglement and vessel strike.

Social structure of Risso’s dolphins (Grampus griseus) at the Azores: a stratified community based on highly associated social units

2008 ◽  
Vol 86 (4) ◽  
pp. 294-306 ◽  
Author(s):  
K. L. Hartman ◽  
F. Visser ◽  
A. J.E. Hendriks
Keyword(s):  
Social Structure ◽  
Site Fidelity ◽  
Adult Males ◽  
Community Based ◽  
Grampus Griseus ◽  
The Social ◽  
Risso's Dolphin ◽  
Social Units ◽  
First Time

In this study, we present for the first time a model for the social structure of Risso’s dolphins ( Grampus griseus Cuvier, 1812). Over the period 2004–2006, 1028 Risso’s dolphins were identified at Pico island, Azores. Individuals sighted on 10 or more occasions were included in the analysis of social structure (n = 183). High resighting rates indicate strong site fidelity for at least part of the population. We found that individuals form stable, long-term bonds organised in pairs or in clusters of 3–12 individuals. Social structure is stratified based on age and sex classes, with strong associations between adult males and between adult females. We suggest that clusters form the basic units of Risso’s dolphin society. Thirteen pods consisting solely of adults, likely males, and 3 pods consisting of mother–calf pairs were identified. Males are organised in stable, long-term associations of varying size that occur throughout the complete range of behavioural states observed. For females, associations can be of similar strength, but the time scale may vary depending on the presence of nursing calves. As subadults, associations also occur (pair formation), but are less stable than those observed for adults. We propose a new model for Risso’s dolphin societies known as a stratified social organisation, which differs from the fission–fusion and matrilineal society models.

scholarly journals Capitoline Dolphins: Residency Patterns and Abundance Estimate of Tursiops truncatus at the Tiber River Estuary (Mediterranean Sea)

Biology ◽  
2021 ◽  
Vol 10 (4) ◽  
pp. 275
Author(s):  
Daniela Silvia Pace ◽  
Chiara Di Marco ◽  
Giancarlo Giacomini ◽  
Sara Ferri ◽  
Margherita Silvestri ◽  
...  
Keyword(s):  
Population Size ◽  
Tursiops Truncatus ◽  
Site Fidelity ◽  
Bottlenose Dolphins ◽  
River Estuary ◽  
Suitable Habitat ◽  
Tyrrhenian Sea ◽  
Abundance Estimate ◽  
Photo Identification ◽  
Tiber River

Periodic assessments of population status and trends to detect natural influences and human effects on coastal dolphin are often limited by lack of baseline information. Here, we investigated for the first time the site-fidelity patterns and estimated the population size of bottlenose dolphins (Tursiops truncatus) at the Tiber River estuary (central Mediterranean, Tyrrhenian Sea, Rome, Italy) between 2017 and 2020. We used photo-identification data and site-fidelity metrics to study the tendency of dolphins to remain in, or return to, the study area, and capture–recapture models to estimate the population abundance. In all, 347 unique individuals were identified. The hierarchical cluster analysis highlighted 3 clusters, labeled resident (individuals encountered at least five times, in three different months, over three distinct years; n = 42), part-time (individuals encountered at least on two occasions in a month, in at least two different years; n = 73), and transient (individuals encountered on more than one occasion, in more than 1 month, none of them in more than 1 year; n = 232), each characterized by site-fidelity metrics. Open POPAN modeling estimated a population size of 529 individuals (95% CI: 456–614), showing that the Capitoline (Roman) coastal area and nearby regions surrounding the Tiber River estuary represent an important, suitable habitat for bottlenose dolphins, despite their proximity to one of the major urban centers in the world (the city of Rome). Given the high number of individuals in the area and the presence of resident individuals with strong site fidelity, we suggest that conservation plans should not be focused only close to the Tiber River mouths but extended to cover a broader scale of area.

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