Noninvasive assessment of seasonal hormone profile in captive bald eagles (Haliaeetus leucocephalus)

The hypothesis was to test whether a ratio of estrogen:androgen in eagle feces would reflect gonadal activity, and whether our procedure for noninvasive hormone analysis of fecal steroids could be applied to assess seasonal reproductive function in four captive bald eagles (Haliaeetus leucocephalus). Total immunoreactive excretory estrogens (E) and testosterone (T) were analyzed and compared as an E/T ratio from ad libitum monthly stool collections during the 1980–81 breeding season of birds maintained in an artificial insemination (AI) project. Since active male gonads are known to secrete a preponderance of androgens into the peripheral circulation and that renal clearance filters steroid metabolites into the urine, it was reasonable to assume that a lowered excretory E/T profile would mimic major changes in male seasonal steroidogenesis; analogously, active female gonads would result in an increased excretion of urinary estrogens, in turn reflected by a seasonal elevation of E/T ratios. A serial profile of excretory E/T ratio data for two male bald eagles approximated unity values except for a midseason low (x < 0.4) in February, one month prior to semen collections, followed by a significant end-of-breeding season rise in E/T values (x > 2.5, P < 0.01). The average E/T profile from data of two female eagles were two- to sixfold higher than males except for a significant mid-breeding season peak in E/T values during March (x > 13.5, P < 0.01). Despite the absence of nest building or egg production by either female, these preliminary observational data indicated seasonal patterns of gonadal activity in both female eagles that were synchronous with semen availability from adjacent males.     

Fatal neonatal toxoplasmosis in a bobcat (Lynx rufus)

Toxoplasma gondii was found in tissues of a captive 1-week-old bobcat (Lynx rufus) that died of myocarditis, hepatitis and encephalitis. Although infection is common in wild Felidae, clinical toxoplasmosis is rarely seen. In this case, the infection was apparently congenitally acquired.     

Fatal toxoplasmosis in koalas (Phascolarctos cinereus)

Toxoplasma gondii-like organisms were seen in the heart, kidney, liver, lung, lymph node, spleen, small intestine, and stomach from 2 koalas that died suddenly in a fauna park in Sydney, Australia. Diagnosis was confirmed by immunohistochemical staining. This is the first confirmed report of toxoplasmosis in an arboreal marsupial.     

Food of the white-tailed eagle Haliaeetus albicilla in Greenland

Six nests of white-tailed eagles in the southernmost Greenland were watched during the nestling period and food items recorded photographically by remote controlled cameras. The species composition of the food was representative even for the adult eagles' diet. Fish made up a major part of 90%, various bird species and arctic fox pups the remaining 10%. The total intake of an eaglet amounted lo 50 kg from hatching to fledging. The daily requirements of fledglings, some 800 g fish food, are equal to previously reported values for older birds. The rate of food consumption of eaglets is constant through most of the nestling period.     

Reproduction of the white-tailed sea eagle Haliaeetus albicilla in Sweden

Sixty-eight white-tailed sea eagle territories were studied on the Swedish Baltic coast in 1964–1982 and 22 territories in Swedish Lapland in 1976–1982. Older data were assembled for comparison. The breeding frequency of adult pairs was high in both study areas (ca. 90%). Median egg-laying dates were 17 March (Baltic) and 7 April (Lapland). Average clutch size and egg volume did not differ between samples from the Baltic taken between 1856 and 1982. Average clutch size was significantly smaller in Lapland (1.6 eggs) than on the Baltic coast (2.1 eggs). Clutch size in Lapland was positively related to carrion availability during March. Nestling survival was significantly lower in Lapland, due to starvation in broods of more than one young. Brood loss was significantly more frequent in Lapland. At the Baltic, nest success decreased from 75 to 22%, and brood size from 1.8 to 1.2, from the early 1950's to the mid 1960's. Nest success in 1976-1982 was significantly lower at the Baltic (26%) than in Lapland (45%), with a much larger proportion of consistently failing pairs. The proportion of eggs laid that resulted in fledged young was estimated at 16% at the Baltic and 39% in Lapland. It is concluded that egg production and nestling survival were suppressed by limited food supply and nest success by human interference in Lapland, and that the reproductive impairment of the Baltic population was due primarily to contamination with toxic substances, mainly DDE.     

Identification of the sex chromosomes in the bald eagle.

Karyotypes of five American bald eagles (Haliaeetus leucocephalus and H. alacanus) are compared. All had 2n=66 chromosomes which fell into 3 size groups: A, 20 pairs of biarmed chromosomes; B, 9 pairs of acrocentric chromosomes and C, 4 pairs of microchromosomes. C-banding was done in two eagles and a heterochromatic W chromosome was identified in a presumptive female. The ZZ and ZW chromosomes could be identified in the karyotypes.     

Mercury in bald eagle nestlings from South Carolina,USA

Bald eagles (Haliaeetus leucocephalus) may be at risk from contaminants in their diet and young birds may be particularly sensitive to contaminant exposure. To evaluate potential risks from dietary mercury exposure to eagle nestlings in South Carolina (USA), we surveyed mercury concentrations in 34 nestlings over two breeding seasons (1998 and 1999). Samples were also obtained from several post-fledging eagles in the region. Nestling feather mercury ranged from 0.61-6.67 micrograms Hg/g dry weight, nestling down mercury from 0.50-5.05 micrograms Hg/g dry weight, and nestling blood mercury from 0.02-0.25 microgram Hg/g wet weight. We did not detect significant differences in tissue mercury between nestlings from coastal and inland regions in contrast to some other studies of piscivorous birds. Mercury concentrations were much higher in the post fledging birds we sampled. Our data show that nestling eagles in South Carolina are accumulating mercury, and that concentrations in older birds may exceed regulatory guidelines.     

Non-invasive sex identification of the white-bellied sea eagle (Haliaeetus leucogaster) through genetic analysis of feathers

The white-bellied sea eagle, Haliaeetus leucogaster, displays reversed sexual size dimorphism and is monomorphic for adult plumage coloration. Early attempts to identify sex in sexually monomorphic birds were based on morphological or chromosomal characters, but since avian W-specific DNA sequences were identified, PCR amplification has become commonly used for molecular sexing. We used a PCR test employing primers that amplify two homologous fragments of both the CHD-W gene, unique to females, and the CHD-Z gene, occurring in both sexes. This test was applied to five individuals of H. leucogaster from the Malacca Zoo and to male and female domestic chickens, Gallus domesticus, for comparison. All individuals were sexed successfully with high reproducibility. We conclude that this PCR-based test with feathers as the DNA source is a reliable sexing method for H. leucogaster. This sexing technique is objective and non-invasive and could be used to test sex ratio theories, as well as to help improve conservation and management actions for captive breeding program of this species in Malaysia.     

Fatal toxoplasmosis and enteroepithelial stages of Toxoplasma gondii in a Pallas cat (Felis manul)

Toxoplasma gondii was found in tissues of a six-year-old female Pallas cat (Felis manul) from the Milwaukee County Zoo. Toxoplasma gondii meronts (types D and E), gamonts, and oocysts were present in the epithelium of the small intestine. Numerous unsporulated oocysts were present in the intestinal lumen. The cat died of acute, overwhelming toxoplasmosis. Necrotic enteritis, multifocal necrotizing granulomatous hepatitis, and pneumonia were the prominent lesions.     

Characteristics of a new hairless mutation (bald) in rats

Hereditarily hairless rats have been maintained by sibmatings since 1973. These animals were termed "bald rats", and examined for their characteristics on genetics, physiological, hematological and clinical chemistry values and histology. The bald rats began to lose their hair at approximately three weeks of age. At five weeks of age, the skin was devoid of all general body hair except for the vibrissae, and the skin became wrinkled at two months of age. Histologically, follicular cysts were observed in a large number, from three months of age onward. The bald condition was a simple recessive character (ba); homozygous animals lost hair and heterozygous ones did not. The bald females attained sexual maturity around eight weeks of age and littered normally, but failed to nurse their young. The incapability of supplying sufficient milk supposedly resulted from the mammary glands that involuted after delivery. The bald animals consumed more food but showed lower values for body weights, plasma triglyceride, and epididymal adipose tissue amount than the haired animals. In addition, the bald males had brown adipose tissue in the interscapulum which was histologically activated as in newborn animals. Aged bald animals showed spontaneous tumors of the thymus, pituitary, testis, uterus, mammary gland, and skin. The incidence of skin tumors was much higher than those of tumors of other origins.     

Genetic structure and phylogeography of a European flagship species,the white‐tailed sea eagle Haliaeetus albicilla

We analysed 120 white‐tailed sea eagles Haliaeetus albicilla from eastern (Poland and Estonia) and southeastern (Serbian Danube population) Europe for genetic variability and structuring at the mitochondrial control region and seven nuclear microsatellite loci. We combined this new dataset with sequence and genotype data from previous analyses covering Greenland and Eurasia (total sample sizes of 420 and 186 individuals for mtDNA and microsatellites, respectively) to address the following questions: 1) does the large eastern population in Europe add significantly to the species‘ overall genetic diversity? 2) Do the new sequence data match the clinal distribution pattern (west to east) of the two major mtDNA lineages? 3) Does the preliminary hypothesis of two nuclear genetic clusters recently found in this species hold for the whole of Europe, and do these clusters show a geographic pattern? Our results confirmed Europe as a stronghold of genetic diversity in white‐tailed sea eagles, and the east of the continent contributed disproportionately to this, the reason being the admixture of eagles with different genetic background. As hypothesised, both mitochondrial lineages were recovered also in eastern Europe, but the globally more eastern lineage was dominant. The presence of two microsatellite clusters was also confirmed, and these groups, too, show a non‐random geographic distribution, with, except for Poland, a high proportion of ‘eastern‐type’ eagles in the populations of east–central and eastern Europe.     

Fatal toxoplasmosis in free-ranging endangered 'Alala from Hawaii

The 'Alala (Corvus hawaiiensis) is the most endangered corvid in the world, and intensive efforts are being made to reintroduce it to its former native range in Hawaii. We diagnosed Toxoplasma gondii infection in five free-ranging 'Alala. One 'Alala, recaptured from the wild because it was underweight and depressed, was treated with diclazuril (10 mg/kg) orally for 10 days. Antibodies were measured before and after treatment by the modified agglutination test (MAT) using whole T. gondii tachyzoites fixed in formalin and mercaptoethanol. The MAT titer decreased four-fold from an initial titer of 1:1,600 with remarkable improvement in physical condition. Lesions of toxoplasmosis also were seen in two partially scavenged carcasses and in a third fresh intact carcass. Toxoplasma gondii was confirmed immunohistochemically by using anti-T. gondii specific serum. The organism was also cultured by bioassay in mice from tissues of one of these birds and the brain of a fifth 'Alala that did not exhibit lesions. The life cycle of the parasite was experimentally completed in cats. This is the first record of toxoplasmosis in 'Alala, and the parasite appears to pose a significant threat and management challenge to reintroduction programs for 'Alala in Hawaii.     

Recovery dynamics and viability of the white-tailed eagle (<Emphasis Type="Italic">Haliaeetus albicilla</Emphasis>) in Germany

Understanding the effect of protection measures on recovery of endangered populations is crucial for assessing the efficiency of management plans. Following the ban of DDT, PCB and other detrimental chemicals in the 1970s, the German white-tailed eagle population recovered rapidly. Using nest monitoring data, dead recovery data and population dynamics models, we examined both short and long-term viabilities of the population. Between 1991 and 2005 the proportion of breeding pairs with an active nest among territorial pairs was α = 0.88 ± 0.007. Annual breeding success was γ = 0.62 ± 0.014. Mean fledged brood size was b = 1.50 ± 0.010 fledged/successful breeding pair. The analysis of dead recovery data of 1,273 individuals ringed as nestling between 1991 and 2006 allowed survival rates to be estimated. We needed to distinguish between “young” (5 years old) and “old” (older than 5 years) adults. Furthermore the annual survival rate was higher for juvenile and immature birds (0.921 ± 0.024) than for adults (s _“young” = 0.760 ± 0.097 and s _“old” = 0.875 ± 0.079), a pattern presumably explained by territorial fights. Finally, an age structured model was used to examine the joint effect of population regulation, environmental and demographic stochasticities. All results indicated that only pessimistic scenarios could lead to substantial extinction probabilities within 100 years. We conclude that management measures were successful in removing the main extinction factors of the population and that future conservation efforts need to focus on the remaining ultimate extinction causes.