Martti Hario

Use of Serum Biochemistry to Evaluate Nutritional Status and Health of Incubating Common Eiders (Somateria mollissima) in Finland

During 1997–1999, we collected serum samples from 156 common eider (Somateria mollissima) females incubating eggs in the Finnish archipelago of the Baltic Sea. We used serum chemistry profiles to evaluate metabolic changes in eiders during incubation and to compare the health and nutritional status of birds nesting at a breeding area where the eider population has declined by over 50% during the past decade, with birds nesting at two areas with stable populations. Several changes in serum chemistries were observed during incubation, including (1) decreases in serum glucose, total protein, albumin, β‐globulin, and γ‐globulin concentrations and (2) increases in serum uric acid, creatine kinase, and β‐hydroxybutyrate concentrations. However, these changes were not consistent throughout the 3‐yr period, suggesting differences among years in the rate of carbohydrate, lipid, and protein utilization during incubation. The mean serum concentrations of free fatty acids, glycerol, and albumin were lowest and the serum α‐ and γ‐globulin levels were highest in the area where the eider population has declined, suggesting a role for nutrition and diseases in the population dynamics of Baltic eiders.

Isolation and Characterization of a Reovirus from Common Eiders (Somateria mollissima) from Finland

SUMMARY. Samples of brain, intestine, liver, lung, spleen, and bursa of Fabricius were collected from five common eider (Somateria mollissima) duckling carcasses during a die-off in the western Gulf of Finland (59°50′N, 23°15′E) in June 1996. No viral activity was observed in specific-pathogen-free chicken embryos inoculated with tissue suspensions, but samples of bursa of Fabricius from three birds were positive when inoculated into Muscovy duck (Cairina moschata) embryo fibroblasts. The isolates were characterized as nonenveloped RNA viruses and possessed several characteristics of the genus Orthoreovirus. Virus particles were icosahedral with a mean diameter of 72 nm and were stable at pH 3.0; their genome was separated into 10 segments by polyacrylamide gel electrophoresis. Mallard (Anas platyrhynchos) ducklings experimentally infected with the eider reovirus showed elevated serum activities of aspartate aminotransferase, creatine kinase, and lactate dehydrogenase enzymes and focal hemorrhages in the liver, spleen, and bursa of Fabricius. During 1997–99, the prevalence of neutralizing antibodies to the isolated virus ranged from 0 to 86% in 302 serum samples collected from incubating eider hens at three nesting areas along coastal Finland. The highest seroprevalence was found in Hanko in 1999, just weeks before reports of an uninvestigated mortality event resulting in the death of an estimated 98% of ducklings at that location. These findings raise the question of potential involvement of the virus in poor duckling survival and eider population declines observed in several breeding areas along coastal Finland since the mid-1980s.

Lead poisoning and trace elements in common eiders Somateria mollissima from Finland

We collected carcasses of 52 common eider Somateria mollissima adults and ducklings and blood samples from 11 nesting eider hens in the Gulf of Finland near Helsinki in 1994, 1995 and 1996. Samples of liver tissue were analysed for arsenic, cadmium, chromium, copper, iron, lead, magnesium, manganese, mercury, molybdenum, selenium and zinc. Blood was analysed for lead, mercury and selenium. Most of the 21 adults examined at necropsy were emaciated with empty gizzards, and no ingested shotgun pellets or other metal were found in any of the birds. Three adult females had a combination of lesions and tissue lead residues characteristic of lead poisoning. Two of these birds had acid-fast intranuclear inclusion bodies in renal epithelial cells and high concentrations of lead (73.4 and 73.3 ppm; all liver residues reported on dry weight basis) in their livers. The third was emaciated with a liver lead concentration of 47.9 ppm. An adult male had a liver lead concentration of 81.7 ppm, which is consistent with severe clinical poisoning. Two other adults, one male and one female, had liver lead concentrations of 14.2 and 8.03 ppm, respectively. Lead concentrations in the blood of hens ranged from 0.11 to 0.63 ppm wet weight. Selenium residues of ≥60 ppm were found in the livers of five adult males. Selenium concentrations in the blood of hens ranged from 1.18 to 3.39 ppm wet weight. Arsenic concentrations of 27.5–38.5 ppm were detected in the livers of four adult females. Detectable concentrations of selenium, mercury and molybdenum were found more frequently in the livers of adult males arriving on the breeding grounds than in incubating females, while the reverse was true for arsenic, lead and chromium. Mean concentrations of selenium, copper and molybdenum were higher in the livers of arriving males than in the livers of incubating hens, but hens had greater concentrations of iron and magnesium. Concentrations of trace elements were lower in the livers of ducklings than in the livers of adults.

INFECTIOUS BURSAL DISEASE VIRUS ANTIBODIES IN EIDER DUCKS AND HERRING GULLS

Abstract We measured antibodies to infectious bursal disease virus (IBDV) in blood of nesting Common Eider (Somateria mollissima) females and immature Herring Gulls (Larus argentatus) in the Baltic Sea, and in blood of Spectacled Eider (Somateria fischeri) females nesting in a remote area of western Alaska. Positive (≥ 1:16) IBDV titers occurred in 75% of the eiders and 45% of the Herring Gull chicks. In eiders, the prevalence of positive titers differed among locations. We found no evidence that IBDV exposure impaired the immune function of Herring Gull chicks, based on their response to inoculation of sheep red blood cells. We suggest that eider ducks and Herring Gulls have been exposed to IBDV, even in locations where contact with poultry is unlikely. The presence of this virus in wild bird populations is of concern because it causes mortality of up to 30% in susceptible poultry.

AN EXPERIMENTAL STUDY ON THE EFFECTS OF POLYMORPHIASIS IN COMMON EIDER DUCKLINGS

Eight common eider (Somateria mollissima) ducklings were experimentally infected from 1 June through 13 June, 1995 with acanthocephalans (Polymorphus minutus) by allowing the birds to feed on Gammarus spp. (Gammarus oceanicus, G. salinus, G. zaddachi, and G. lacustris) containing acanthocephalan cystacanths. Uninfected Gammarus spp. were fed to a control group of seven ducklings. No mortality of ducklings occurred during the experiment. However, the infected ducklings gained weight more slowly than the control birds. After the 2 wk study period, the mean serum concentrations of total protein, albumin, β-globulin, γ-globulin, fructosamine and creatine kinase were lower in the infected group than in the controls. The mean (±SE) number of acanthocephalans in the intestine of the infected ducklings was 21 (±4). The parasites were attached to the mucosa of the posterior small intestine of the infected ducklings with a mixed inflammatory reaction consisting of heterophils and mononuclear lymphocytes surrounding the attachment sites.

Parental investment by the sexes in the Herring Gull: the use of energy reserves during early breeding

A sample of culled birds was used to determine weight change and size of endogenous nutrient reserves in male and female Herring Gulls Larus argentatus during the period from colony occupation to late incubation. Both sexes showed considerable variation in body condition according to breeding phase. The most striking difference between the sexes was found in lipid contents prior to laying. Whereas males tended to deplete endogenous fat, females gained fat. There was no marked change in protein reserves in either sex. It is concluded that males meet maintenance costs during courtship feeding by using a great deal of their endogenous fat while saving the proteins. This is done in favour of the body condition of the laying female, males thus equalizing the initial parental investment of the two sexes. Both sexes regained energy reserves during incubation, being in equal physiological condition when the

Breeding success and breeding population trends of waterfowl: implications for monitoring

Abstract Traditional waterfowl monitoring includes only breeding or non-breeding population sizes, but the assessment of breeding success would provide valuable information for the interpretation of population trends, as well as for the early targeting of management measures and further studies. The relationship between breeding success and subsequent breeding population trends is not very well-known in particular for many waterfowl species. Using transfer function (TF) models, we analysed the relationship between breeding success measured as duckling numbers and post-breeding population sizes (i.e. the numbers of adults and ducklings in July), and subsequent breeding population trends for the mallard Anas platyrhynchos, common eider Somateria mollissima, common merganser Mergus merganser and goldeneye Bucephala clangula in Aasla, an island in southwestern Finland. In addition, we used data on the common eider in Söderskär, an island group in the Gulf of Finland, to analyse the extent to which fledgling numbers transform into recruitment and breeding population size. As a complement to the traditional methods of population monitoring, we present a simple and cost-effective method for the assessment of breeding success: the monitoring of post-breeding population sizes (including both adults and young). The breeding population sizes of the mallard, common eider and common merganser were positively related to their breeding success with a time lag corresponding to their recruitment age. For the common eider, the effect of the recruitment number on subsequent breeding population size seemed to last for up to three years after recruitment. There was a coupling between the post-breeding sizes and the subsequent breeding population sizes of the mallard, common eider and goldeneye with a lag corresponding to the recruitment age for the mallard and the common eider, but for goldeneye, one year later than the usual recruitment age. The chicks seem to recruit to the local breeding population to an extent that is sufficient for affecting local breeding population trends. Our results indicate that the annual breeding success of our target species can be assessed on the basis of their post-breeding population sizes. This easy and rapid monitoring method for breeding success is also suitable for voluntary bird watchers.

Polychlorinated biphenyls in diseased lesser black-backed gull (Larus fuscus fuscus) chicks from the Gulf of Finland.

Diseases due to the degeneration of the liver and various other internal organs were the major cause of the exceedingly high chick mortality in lesser black-backed gulls (Larus fuscus fuscus) in the central Gulf of Finland, Baltic Sea, during 1991-1993. The same symptoms were found in chicks of common gulls (Larus canus) and herring gulls (Larus argentatus) from the same focal area, although at a much lower frequency. We found disproportionately high concentrations of polychlorinated biphenyls (PCBs) in liver relative to leg muscle in lesser black-backed chicks compared with common gull and herring gull chicks. The causality between PCB residues and chick diseases remains unknown. No signs of chick edema disease or abnormal frequency of embryonic deaths, commonly associated with organochlorines in biota, were found. It is concluded that studies made in a very small geographical area may not give a good correlation between dose and effect due to an even greater variation in tolerance. Another explanation is that the diseases may not have been PCB-induced.

Effects of mate removal on the fecundity of common eider Somateria mollissima females

Behavioural observations, measurements of male and female reproductive success, and DNA microsatellite loci were used to investigate parentage of common eider Somateria mollissima clutches and productivity of widowed females in Finland. In an experimental study simulating spring harvest of male eiders, a total of 20 males were shot while attending 16 females (four males after rematings, 16 initial males) during the pre-laying and laying period in 1994. Of the 16 widowed females, 11 nested and five did not. Mean clutch size of breeding widows (4.55) did not differ from that of control females in the same year (4.47; N = 32). However, the hatching success of widows was significantiy lower than that of control females (53 vs 81%) because of a greater proportion of addled eggs and dead embryos (38% vs 11%). Male removal also appeared to change male and female behaviours resulting in higher incidence of intra-specific brood parasitism and mate replacement. Occurrence of foreign eggs averaged 9.5% during the treatment year but was not observed during a year without disturbance during mating and egg laying (1997). Behaviours of widowed females related to remating attempts varied from active seeking of new mates to total rejection of courting males. Rematings did not lead to full clutch fertilisation among widowed females. Neither did we observe evidence of immigration of new males into the hunting area to court the widows. Male removal clearly lowered the fecundity of eider females, reducing nesting success by 35% of long-term averages. The potential for remating appears to be reduced by the female-biased sex ratio caused by simulated male-only harvest.