CHANGES IN MORPHOLOGY WITH AGE IN MEDITERRANEAN MONK SEALS (MONACHUS MONACHUS)

In order to describe the pelage and external appearance of the Mediterranean monk seal ( Monachus monachus ) and prepare an age-sex classification guide, 120 seals from the Cabo Blanco Peninsula colony in the Western Sahara/Mauritania were periodically photographed between 1993 and 1996. Analysis of the pigmentation pattern, pelage color and pattern of natural markings of each seal established 48 phenetic types, which were, in turn, arranged in five groups (morphological classes) with multivariate cluster analysis (UPGMA). The variables that best define these groups are size and color. The variation related to relative size, sex and age of 26 identified seals monitored over three years showed that: (1) after each molt, external appearance varied considerably only in non-adults, while adult appearance was invariable; (2) marked sexual dimorphism exists in adults' external appearance; and (3) a remarkable similarity of adult and neonate pelage exists. With these results, we propose an age-sex classification guide to facilitate monk seal identification in the field.     

DIVING DEVELOPMENT AND BEHAVIOR OF A REHABILITATED MEDITERRANEAN MONK SEAL (MONACHUS MONACHUS)

Among the priority actions identified for saving the critically endangered Mediterranean monk seal are gaining basic biological information on movements and behavior, and rescuing and rehabilitating wounded, stranded, and orphaned pups. On 22 May 2004 a rehabilitated monk seal juvenile was fitted with a satellite tag, released in the National Marine Park of Alonnisos, Northern Sporades, Greece, and monitored for 167 d. Postrelease, the seal remained close to the islands of the park and within the 200-m isobath. Throughout the monitoring period, the seal reduced time hauled out, while 95-percentile dive duration and depth gradually increased. The overall maximum depth of 123 m recorded in this study is the greatest depth ever recorded for the species. These results confirm the effectiveness of the rehabilitation program carried out on the particular animal and provide additional support for the continuation of the rehabilitation program as a conservation measure for the species. We demonstrate that satellite tracking of rehabilitated seals is a valuable research and conservation tool, even for a species that commonly uses shoreline caves for resting, molting, and parturition.     

NEST-BUILDING BEHAVIOUR OF QUAKER PARROTS MYIOPSITTA MONACHUS

An account is given of nest-building by captive Quaker Parrots Myiopsitta monachus. Nests were made by thatching movements, twigs being inserted into a base by a sideways movement of the head. A downward slanting sheaf was formed around an internal cavity. The lip of the nest-hollow was formed by pulling up and inserting the ends of some twigs. The cavity was shaped by chewing off projecting ends, and floored with chewed and shredded twigs.     

PUP SURVIVAL IN THE MEDITERRANEAN MONK SEAL (MONACHUS MONACHUS) COLONY AT CABO BLANCO PENINSULA (WESTERN SAHARA-MAURITANIA)

We surveyed pup survival in Mediterranean monk seals ( Monachus monachus ), at Cabo Blanco Peninsula (Western Sahara-Mauritania) colony from May 1993 to December 1997. This species breeds and hauls out on beaches inside two main caves. During the study period we detected a total of 93 pups that died or disappeared. The survival rate of 84 pups through the age of first moult (approximately two months) was 0.47. This value is similar to those reported for other pinnipeds breeding in caves but lower than for those breeding on open beaches. Mortality varied seasonally and appeared to increase as a result of storms, large ocean swells, and high tides. Mother-pup pair separation (and resulting pup starvation) and physical injury caused by impact against the rock walls of the cave and cliffs were established as the causes of most deaths. Beach surface area inside the caves also appeared to be a mediating factor in the effects of sea conditions. High pup mortality may be a limiting growth factor in this population, although cave dwelling protects the population from predators and human disturbance.     

SURVIVAL RATES FOR THE HAWAIIAN MONK SEAL (MONACHUS SCHAUINSLANDI)

Abstract: Endangered Hawaiian monk seal ( Monachs schauinslandi ) pups at all the major breeding islands in the Northwestern Hawaiian Islands have been tagged since the early 1980s. Pups were double flipper tagged as soon as possible post-weaning. With few exceptions, an extensive tag resighting effort was conducted annually at the same islands. These resighting data were used to estimate seal survival rates from the time of tagging to age one at all locations using the ratio of seals alive in the second year to number of pups tagged. These survival rates among the islands, from weaning to age one, averaged over the years of the study, ranged from 0.80 to 0.90. For young seals over age one, capture-recapture methods were used to calculate survival pooled through several years, and these rates ranged from 0.85 to 0.98. At French Frigate Shoals and Laysan Island, the higher numbers of tagged pups allowed separate estimates of male and female survival to be calculated. These rates suggested that survival of immature females was better than males. Beginning in 1989, survival of immature seals at French Frigate Shoals declined sharply.     

HAWAIIAN MONK SEALS (MONACHUS SCHAUINSLANDI) FORAGING IN DEEP-WATER CORAL BEDS

Plans to harvest deep-water corals in the remote Northwestern Hawaiian Islands, close to populations of endangered Hawaiian monk seals ( Monachus schauinslandi ), have raised concerns about the seals' use of deep-water habitats. Movements and diving patterns of seals studied at French Frigate Shoals (FFS) Atoll indicated two areas where five males out of 33 instrumented seals dove deep enough (300–500 m) to encounter commercially sought deep-water corals. Submarine surveys conducted at each location found beds of gold ( Gerurdia sp.) and pink ( Corallium sp.) precious coral suggesting an overlap between the foraging habitat of some seals and the target of the coral fishery. Areas adjacent to the coral beds that were visually censused using submersibles showed significantly fewer precious corals. Precious coral beds were not found on previous submarine surveys at other regions around FFS, supporting the notion that seals were selecting the areas with corals as forage habitat. Five male seals were fitted with back-mounted video cameras to document feeding among precious corals. None of the five seals dove deep enough to encounter precious corals (>300 m). However, three of the seals visited beds of black coral ( Cirrhipdhes sp.) at shallower depths (∼ 80 m). One seal was observed revisiting the black coral beds on three successive nights to feed on fish hiding among the coral stems.     

ANNUAL REPRODUCTIVE CYCLE OF THE FEMALE HAWAIIAN MONK SEAL (MONACHUS SCHAUINSLANDI)

Abstract: The annual reproductive cycle is described for the adult female Hawaiian monk seal ( Monachus schauinslandi ) from data collected at Laysan Island (1982–1991) and Lisianski Island (1982–1983) in the Northwestern Hawaiian Islands. Pupping, lactation, weaning, and molting were directly observed, while mating was rarely observed and was, therefore, inferred from the occurrence of mounting injuries and from adult male and female association patterns. Pooled birth rates during the study period were 0.544 for all adult-sized females and 0.675 for females parous in earlier years. For parturient females, pupping peaked in late March and early April, weaning in May, mounting injuries in May and June, and molting in July. For non-parturient females, the median mounting injury and molting dates occurred 17 and 28 days earlier, respectively. Pupping date set the timing of subsequent events in the annual cycle, but the timing of those events was adjusted by loss of the pup or poor physical condition of the female. Individual pupping patterns varied widely. The mean interval for births in consecutive years was 381 days; females that pupped in consecutive years gave birth later each season. Conversely, females who skipped a year or more gave birth earlier their next pupping season.     

ANALYSIS OF CORPORA LUTEA TO ESTIMATE REPRODUCTIVE CYCLES OF WILD HAWAIIAN MONK SEALS (MONACHUS SCHAUINSLANDI)

Ovaries from 14 female Hawaiian monk seals, O-24 yr of age, collected from the northwestern Hawaiian Islands were analyzed by gross and histological examination for the presence of corpora hemorrhagica (CH), lutea (CL), albicantia (CA), and dominant follicles. Seven seals, 5-24 yr of age, were mature females, and another seven seals, O-5 yr of age, were immature based on the presence or absence of CL and CA in the ovaries. Two 5-yr-old seals did not have CL and CA, but one J-yr-old and both 6-yr-old seals had CL or CA. In addition, the weight of the more active ovary increased at 5 yr of age, indicating that puberty in these female Hawaiian monk seals occurred about 5 yr of age. The total number of CL and CA was significantly correlated to the ovarian weight, but not age of the seals, indicating that visible CA of Hawaiian monk seals probably degenerate within a year. If an ovulation resulted in pregnancy, we assumed that the resulting CL from that pregnancy persisted throughout gestation and regressed approximately 2 yr after ovulation. However, the CL of pregnancy were not easily differentiated from cyclic CL that did not result in pregnancy. Four of seven mature seals were clearly polyestrous from the analyses of their ovaries and reproductive histories. The remaining three seals were pregnant in previous consecutive years, and we could not positively determine whether they were also polyestrous. The ovaries from Hawaiian monk seals had unusually large, rounded granular cells containing the aging pigment, lipofuscin. These cells were located between loose fibrous tissues in all regressing CL and CA but were not present in any CH.     

BODY SIZE,SURVIVAL, AND DECLINE OF JUVENILE HAWAIIAN MONK SEALS,MONACHUS SCHAUINSLANDI

In the mid 1980s half of the entire Hawaiian monk seal species was located at French Frigate Shoals, and this colony may have reached environmental carrying capacity. Since 1989 this colony has declined by 55%, primarily from poor juvenile survival. Only 8%–25% of weaned pups have survived to age 2 during this period, compared to at least 80% between 1984 and 1987. We characterize (1) this drop in survival, (2) a strong, but variable, correlation between survival and size at weaning, (3) interisland differences in size from weaning to age 2 in 1991 through 1993, and (4) decadal-scale changes in mean measures of size at weaning. We compare observations at French Frigate Shoals with the colony at Laysan Island where abundance is well below historical levels and was therefore expected to be below carrying capacity. At Laysan Island juvenile survival has also been poor (30%-70%), and the size of weaned pups has decreased during the past decade. Our hypothesis is that poor survival may be due to reduced prey availability at both sites, but particularly at French Frigate Shoals. Evidence to support this hypothesis includes a large increase in total abundance at French Frigate Shoals; reduced size of weaned pups; decreased survival, emaciation, and slower growth rates of juvenile seals; and declining primary productivity. Regardless of cause, the immediate consequences at French Frigate Shoals and Laysan Island, and for the species overall, will likely be poor recruitment and productivity. Because the decline is still in progress, the ultimate consequences for the species' viability are of great concern in light of its already low abundance.     

MORPHOMETRY, HEMATOLOGY, AND SERUM CHEMISTRY IN THE HAWAIIAN MONK SEAL (MONACHUS SCHAUINSLANDI)

We studied morphometric, hematology, and serum chemistry variables in 140 Hawaiian monk seals ( Monachus schauinslandi ) to establish normal baseline values for these variables among free-living seals. We compared seals at French Frigate Shoals (FFS), Midway Atoll (MID), and Pearl and Hermes Reef (PHR) because these subpopulations differ in their rates of population recovery. Dorsal standard length and axillary girth differed significantly between immature (1–4 yr old) and adult (≥5 yr old) seals among sex and island subgroups. Immature seals at FFS were shorter than those at MID and PHR; adult seals at FFS had smaller dorsal standard lengths and axillary girths compared to the other subpopulations. The differences in size were more pronounced among adult females. Significant differences were also found for hematology and serum chemistry variables among seals at FFS, MID, and PHR. Monk seals at FFS had an absolute lymphopenia and eosinopenia compared to those at MID and PHR, compatible with a stress response. Seals at FFS also had lower blood urea nitrogen than seals at PHR, and a lower plasma potassium than seals at MID or PHR. Monk seals had an absolute and relative eosinophilia compared to previously published values. Analysis of subpopulation differences is useful for population health assessment and for long-term monitoring of an endangered species.     

NEW INFORMATION ON THE NATURAL HISTORY,DISTRIBUTION, AND SKULL SIZE OF THE EXTINCT (?) WEST INDIAN MONK SEAL,MONACHUS TROPICALIS

Our knowledge of the extinct West Indian monk seal, Monachus tropicalis , is scant due to heavy exploitation following European colonization of the New World. We present previously unknown accounts of the species, including unpublished field notes of biologist E. W. Nelson, who observed a small number of wild seals in June of 1900. Records indicate that M. tropicalis may have had a long pupping season, occurred in large groups (up to 100) when abundant, probably ate fish and crustaceans, were preyed upon by sharks, and that young and adult seals may have assorted themselves into different age groups when hauled out. Additional records extend the known range of M. tropicalis to include the north coast of South America as far east as Guyana. We also present previously unavailable measurements from a large series of adult skulls and mandibles ( n = 48). Two cases of histocytosis X, carcinoma, or other disease of the hard palate are documented from among these specimens.     

CONCENTRATIONS OF ESTRONE SULFATE and PROGESTERONE IN PLASMA and SALIVA, VAGINAL CYTOLOGY, and BIOELECTRIC IMPEDANCE DURING THE ESTROUS CYCLE OF THE HAWAIIAN MONK SEAL (MONACHUS SCHAUNSLAnDI)

Blood and saliva samples, vaginal swabs, and bioelectric impedance measurements were collected 1–3 times per week from a captive adult female Hawaiian monk seal ( Monacbus schauinslandi ) during the spring and summer of 1991. During 1992 saliva only was collected on average 4 times weekly. Concentrations of progesterone and estrone sulfate, and the periodic appearance of cornified epithelial cells from the vagina indicated consecutive estrous cycles ranging 35 ± 3 days in duration. Progesterone concentrations in plasma and saliva had a correlation of 0.868, while estrone sulfate had a correlation of 0.982. Bioimpedance of the whole seal body resulted in a pattern similar to the estrone sulfate concentrations, but shifted forward by 2 d. Bioimpedance of the upper vaginal tissues paralleled the estrone sulfate pattern while the bioimpedance of the lower reproductive tract fluctuated without a distinct pattern. The luteal phase ranged 17–20 d and the follicular phase was 15–18 d in length. These results indicate that: (1) the Hawaiian monk seal, in captivity, is a polyestrous seal, in contrast to other phocid seals that have been studied; (2) salivary concentrations of estrogen and progesterone may provide an accurate, less-invasive method of monitoring reproductive hormones in captive Hawaiian monk seals; and (3) vaginal cytology and bioelectric impedance reflect physiological changes associated with the estrous cycle.