4. Monk Seals at the Edge: Blessings in a Time of Peril

2017 ◽  
pp. 117-148 ◽  
Keyword(s):  
Monk Seals

Photogrammetric Estimates of Size and Mass in Hawaiian Monk Seals (Monachus schauinslandi)

2006 ◽  
Vol 32 (1) ◽  
pp. 31-40 ◽  
Author(s):  
Katherine W. McFadden ◽  
Graham A. J. Worthy ◽  
Thomas E. Lacher
Keyword(s):  
Monachus Schauinslandi ◽  
Monk Seals

scholarly journals In-air hearing in Hawaiian monk seals: implications for understanding the auditory biology of Monachinae seals

2021 ◽  
Author(s):  
Brandi Ruscher ◽  
Jillian M. Sills ◽  
Beau P. Richter ◽  
Colleen Reichmuth
Keyword(s):  
Marine Mammals ◽  
Elephant Seal ◽  
Critical Ratio ◽  
Mirounga Angustirostris ◽  
Northern Elephant Seal ◽  
Hearing Ability ◽  
Highly Sensitive ◽  
Monk Seals ◽  
Management And Conservation ◽  
Hearing Abilities

AbstractThe auditory biology of Monachinae seals is poorly understood. Limited audiometric data and certain anatomical features suggest that these seals may have reduced sensitivity to airborne sounds compared to related species. Here, we describe the in-air hearing abilities of a Hawaiian monk seal (Neomonachus schauinslandi) trained to participate in a psychophysical paradigm. We report absolute (unmasked) thresholds for narrowband signals measured in quiet conditions across the range of hearing and masked thresholds measured in the presence of octave-band noise at two frequencies. The behavioral audiogram indicates a functional hearing range from 0.1 to 33 kHz and poor sensitivity, with detection thresholds above 40 dB re 20 µPa. Critical ratio measurements are elevated compared to those of other seals. The apparently reduced terrestrial hearing ability of this individual—considered with available auditory data for a northern elephant seal (Mirounga angustirostris)—suggests that hearing in Monachinae seals differs from that of the highly sensitive Phocinae seals. Exploration of phylogenetic relationships and anatomical traits support this claim. This work advances understanding of the evolution of hearing in amphibious marine mammals and provides updated information that can be used for management and conservation of endangered Hawaiian monk seals.

Significance of wounding to female reproductive success in Hawaiian monk seals (Monachus schauinslandi) at Laysan Island

1993 ◽  
Vol 71 (3) ◽  
pp. 469-474 ◽  
Author(s):  
Lisa M. Hiruki ◽  
Ian Stirling ◽  
William G. Gilmartin ◽  
Thea C. Johanos ◽  
Brenda L. Becker
Keyword(s):  
Reproductive Success ◽  
Adult Male ◽  
Reproductive Rate ◽  
Lactation Period ◽  
Female Reproductive Success ◽  
Monachus Schauinslandi ◽  
Lower Survival Rate ◽  
Adult Females ◽  
Pup Survival ◽  
Monk Seals

We studied reproductive rate, length of lactation period, pup survival, and mortality of injured and uninjured female Hawaiian monk seals (Monachus schauinslandi) on Laysan Island, northwestern Hawaiian Islands, in 1983 – 1989. The severity and timing of nonfatal injuries were influential in determining their effect on female reproductive success. There was a tendency towards a shorter mean lactation period and lower survival rate of pups for females with major injuries than for uninjured females. Females with minor injuries were similar to uninjured females in terms of reproductive rate, length of lactation, and pup survival. For females injured shortly before the birth of their pup or during lactation, pup survival was lower than for uninjured females, whereas for females injured during the year prior to pupping, measures of reproductive success were not significantly different from those for uninjured females. Immature (aged 4 – 8 years) females entering the reproductive population were injured by adult male seals significantly more often than females aged 0 – 3 years, but at a similar rate to adult females. The major effect of injuries on female reproductive success is an increase in female mortality: 87.5 % of the adult females (n = 16) that died on Laysan Island in 1983 – 1989 sustained injuries from adult male seals.

scholarly journals First monk seal from the Southern Hemisphere rewrites the evolutionary history of true seals

2020 ◽  
Vol 287 (1938) ◽  
pp. 20202318
Author(s):  
James P. Rule ◽  
Justin W. Adams ◽  
Felix G. Marx ◽  
Alistair R. Evans ◽  
Alan J. D. Tennyson ◽  
...  
Keyword(s):  
Southern Hemisphere ◽  
North Atlantic ◽  
Marine Mammals ◽  
Evolutionary History ◽  
Major Change ◽  
The North ◽  
History Of ◽  
Entire History ◽  
The North Atlantic ◽  
Monk Seals

Living true seals (phocids) are the most widely dispersed semi-aquatic marine mammals, and comprise geographically separate northern (phocine) and southern (monachine) groups. Both are thought to have evolved in the North Atlantic, with only two monachine lineages—elephant seals and lobodontins—subsequently crossing the equator. The third and most basal monachine tribe, the monk seals, have hitherto been interpreted as exclusively northern and (sub)tropical throughout their entire history. Here, we describe a new species of extinct monk seal from the Pliocene of New Zealand, the first of its kind from the Southern Hemisphere, based on one of the best-preserved and richest samples of seal fossils worldwide. This unanticipated discovery reveals that all three monachine tribes once coexisted south of the equator, and forces a profound revision of their evolutionary history: rather than primarily diversifying in the North Atlantic, monachines largely evolved in the Southern Hemisphere, and from this southern cradle later reinvaded the north. Our results suggest that true seals crossed the equator over eight times in their history. Overall, they more than double the age of the north–south dichotomy characterizing living true seals and confirms a surprisingly recent major change in southern phocid diversity.

Hawaiian Monk Seals

2015 ◽  
pp. 117-136 ◽  
Author(s):  
Rachel S. Sprague ◽  
Megan M. Draheim
Keyword(s):  
Monk Seals

The production and reception of underwater sound in Hawaiian monk seals (Neomonachus schauinslandi)

2018 ◽  
Vol 144 (3) ◽  
pp. 1741-1741
Author(s):  
Jillian Sills ◽  
Kirby Parnell ◽  
Colleen Reichmuth
Keyword(s):  
Underwater Sound ◽  
Monk Seals

scholarly journals Circumstantial evidence for the presence of monk seals in the West Indies

Oryx ◽  
1998 ◽  
Vol 32 (4) ◽  
pp. 310-316 ◽  
Author(s):  
I. L. Boyd ◽  
M. P. Stanfield
Keyword(s):  
West Indies ◽  
Marine Species ◽  
Circumstantial Evidence ◽  
Harbour Seal ◽  
Sea Lion ◽  
The West ◽  
The Past ◽  
The Caribbean ◽  
Monk Seals

Based on interviews with 93 fishermen in northern Haiti and Jamaica during 1997 an assessment was made of the likelihood that monk seals survive in this region of the West Indies. Fishermen were asked to select marine species known to them from randomly arranged pictures: 22.6 per cent (n = 21) selected monk seals. This number was significantly (P < 0.001) greater than the number who selected control species (walrus, harbour seal, and sea-lion) that they were unlikely to have observed. However, it was not significantly different (n = 19, P > 0.1) from the number who selected manatees, which are known to occur in the region in small numbers. More than 95 per cent of respondents also identified species that are known to occur commonly in the region. Further questioning of the 21 respondents who selected monk seals suggested that 16 (78 per cent) of them had seen at least one in the past 1–2 years. Those fishermen that were able to provide further descriptions gave information about size and colour that was consistent with many of these seals being monk seals. It is possible that the Caribbean monk seal is not extinct.

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