Joanna Burger

Biology of marine birds

Seabirds in the Marine Environment, E.A. Schreiber and J. Burger The Fossil Seabird Fossil Record and the Role of Paleontology in Understanding Seabird Community Structure, K.I. Warheit Seabird Systematics and Distribution: A Review of Current Knowledge, M. de L. Brooke Colonial Breeding in Seabirds, J.C. Coulson Seabird Demography and Its Relationship with the Marine Environment, H. Weimerskirch Foraging Behavior and Food of Seabirds, D.A. Shealer Climate and Weather Effects on Seabirds, E.A. Schreiber Breeding Biology, Life Histories and Life History-Environment Interactions in Seabirds, K.C. Hamer, E.A. Schreiber, and J. Burger Site and Mate Choice in Seabirds: An Evolutionary Approach, J. Bried and P. Jouventin Seabird Communication and Displays, J.B. Nelson and P.H. Baird Energetics of Free-Ranging Seabirds, H.I. Ellis and G.W. Gabrielson Seabird Reproductive Physiology and Energetics, G.C. Whittow Chick Growth and Development in Seabirds, G.H. Visser Water and Salt Balance in Seabirds, D.L. Goldstein Effects of Chemicals and Pollution on Seabirds, J. Burger and M. Gochfeld Interactions Between Fisheries and Seabirds, W.A. Montevecchi Seabird Conservation, P.D. Boersma, J.A. Clark, and N. Hilgarth Shorebirds in the Marine Environment, N. Warnock, M.A. Rubega, and C. Elphick Wading Birds in the Marine Environment, P.C. Frederick Appendix 1: List of Seabird Species Appendix 2: Table of Seabird Species and Life History Characteristics Index

Estimating Annual Survival and Movement Rates of Adults within a Metapopulation of Roseate Terns

Several multistratum capture-recapture models were used to test various hypotheses about possible geographic and temporal variation in survival, movement, and recapture/resighting probabilities of 2399 adult Roseate Terns (Sterna dougallii) color-banded from 1988 to 1992 at the sites of the four largest breeding colonies of this species in the northeastern USA. Linear-logistic ultrastructural models also were developed to investigate possible correlates of geographic variation in movement probabilities. Based on goodness-of-fit tests and comparisons of Akaikes Information Criterion (AIC) values, the fully parameterized model (Model A) with time- and location-specific survival, movement, and capture probabilities, was selected as the most appropriate model for this metapopulation structure. With almost all movement accounted for, on average >90% of the surviving adults from each colony site returned to the same site the following year. Variations in movement probabilities were more closely associated with the identity of the destination colony site than with either the identity of the colony site of origin or the distance between colony sites. The average annual survival estimates (0.74-0.84) of terns from all four sites indicate a high rate of annual mortality relative to that of other species of marine birds.

Metal levels in feathers of 12 species of seabirds from Midway Atoll in the northern Pacific Ocean

Seabirds are excellent subjects for examination of heavy metals because they are long-lived, feed at different distances from land, and exhibit different trophic levels. In this paper we compare the levels of lead, cadmium, mercury arsenic, chromium, manganese, selenium, and tin in the feathers of birds nesting on Midway Atoll in the northern Pacific Ocean. We test the null hypothesis that there are no interspecific differences in the levels of metals in the feathers of the adult black-footed albatross (Diomedea nigripes), Laysan albatross (Diomedea immutabilis), red-footed booby (Sula sula), great frigatebird (Fregata minor), Bonin petrel (Pterodroma hypoleuca), Christmas shearwater (Puffinus nativitatis), red-tailed tropicbird (Phaethon rubricauda), wedge-tailed shearwater (Puffinus pacificus), brown noddy (Anous stolidus), sooty tern (Stema fuscata), grey-backed tern (Stema lunata), and white tern (Gygis alba), and young of some of these species. There were interspecific differences in the levels of all metals for adults. Christmas shearwater had the highest levels of lead, cadmium, selenium and manganese, but the second lowest levels of mercury. In general, metal levels were the lowest in the smallest species (white tern), but were not the highest in the largest species (black-footed albatross), except for manganese, arsenic and mercury. There was a high variance in metal levels among adults for some species, but not for others. White tern adults were variable for lead, while Christmas shearwaters were variable for lead and cadmium. Compared to the means for metals in other birds generally (after Burger, 1993), Christmas shearwaters had higher levels of lead, white terns, brown noddy, Christmas shearwater, frigatebirds and Laysan albatrosses had higher levels of cadmium, and bonin petrel, wedge-tailed shearwater, tropicbirds, frigatebirds, red-footed boobies, and both albatrosses had higher levels of mercury. Whereas the means for lead and cadmium were below the known effects levels, some individuals had levels high enough to cause adverse effects in the birds. The mean values for mercury in Bonin petrel, red-tailed tropicbird, and black-footed albatross were higher than the levels known to cause adverse reproductive and behavioral effects.

Marine Birds as Sentinels of Environmental Pollution

Marine birds are useful as bioindicators of environmental pollution in estuarine and marine environments because they are often at the top of the food chain, ubiquitous, and many are abundant and common, making collecting possible. Seabirds have the advantage of being large, wide-ranging, conspicuous, abundant, long-lived, easily observed, and important to people. Many species are at the top of the food chain where they bioaccumulate contaminants with age. One disadvantage is that many species are migratory, making it difficult to determine where exposure occurred. This can be eliminated by using sedentary species or young birds that obtain all their food from parents. Further, noninvasive collection of feathers can be used to assess heavy metal levels, both from current collections and from historical collections in museums dating back centuries. Marine birds can be used as bioindicators in many ways, including tissue levels of contaminants, epidemiological field studies of effects, and experimental and laboratory studies of dose and effects. Examples from our research indicate some of the ways marine birds can be useful as indicators and sentinels of contamination, particularly by using young birds and feathers.

The effect of human activity on birds at a coastal bay

Abstract I examined the direct and indirect effects of human activity on birds at a coastal bay refuge along the Atlantic Coast. Over the year, human activity varied at different sample sites on the refuge, but people were present on part of the refuge every day, although activity was concentrated on designated paths around a freshwater pond and at a fishing pier. On the refuge (exclusive of the ponds) people were present at the sample sites 17% of the time, birds were present 42% of the time when people were present, but birds were present 72% of the time when people were absent. Human activities, such as jogging or grass mowing, which involved rapud movement or close proximity to roosting birds, usually caused them to flush. Slow-walking bird watchers and clammers did not usually cause birds to flush. Gulls and terns were least affected as they usually relanded where they had been, ducks usually flushed and flew to the centre of the pond, and herons, egrets and shorebirds were most disturbed and flushed to distant marshes. These results suggest that if management objectives include providing roosting areas for migrating shorebirds then some areas must be protected from close and fast-moving human activities.

Shorebird diet during spring migration stopover on Delaware Bay

During spring migration, thousands of shorebirds gather in Delaware Bay at the same time as horseshoc crabs (Linudus polyphemus) are spawning. During their stopover, the birds store enough fuel in the form of fat and muscle protein to complete their migration to the Canadian breeding grounds. We documented the changes in body mass of shorebirds migrating through Delaware Bay and determined how much of the shorebird diet during this period consisted of horseshoc crab eggs. Migrating shorebirds were captured, morphometric measurements taken, and gut samples collected by stomach flushing. Red Knots (Calidris canutus). Ruddy Turnstones (Arenaria interpres), Sanderlings (C. alba), and Semipalmated Sandpipers (C. pusilla) increased their body mass up to 70-80% while staging on Delaware Bay. Horseshoe crab egg membranes constituted the bulk of the gut contents for all species at all collection sites. Polychaete and oligochaete worms were found in substantial concentrations in gut samples collected from shorebirds in certain beaches. Sand and unidentified decomposed material were found in varying amounts in gut samples of all species and locations. Apparent declines in spawning horseshoe crab populations may adversely affect migratory shorebirds.

Heavy metals in avian eggshells: another excretion method.

Birds can rid their bodies of heavy metals through both excretion and deposition in feathers, and females can also eliminate heavy metals in the contents of their eggs. In this paper the levels of heavy metals (lead, cadmium, mercury, selenium, manganese, chromium) in the contents and shells of eggs of roseate terns (Sterna dougallii) and herring gulls (Larus argentatus) nesting at Cedar Beach, Long Island, are reported. For both species, metal concentrations were significantly higher in the contents compared to the shells for lead, mercury, selenium, and chromium. For herring gulls, metal levels were higher in the shells for cadmium and manganese. Levels of cadmium, mercury, and selenium were significantly higher in roseate tern egg contents than for herring gulls. In eggshells, lead, cadmium, mercury, and selenium were significantly higher in roseate terns compared to herring gulls. For both species, eggshells account for about 7-8% of the egg by weight, but less than 1% of the egg burden for mercury, 1-5% for lead, selenium, and chromium, and 7-11% for manganese. For cadmium, shells account for only 5% of the egg burden for roseate terns, but 29% for herring gulls. These data suggest that, except for mercury, eggshells provide another method of excretion of metals in these two species of birds.

Effects of tide cycles on habitat selection and habitat partitioning by migrating shorebirds

-We studied assemblages of feeding shorebirds in three intertidal habitats on the coast of New Jersey during August to document how species segregate spatially both among and within habitats and to determine the effects of tidal cycles on these patterns. The habitats were a sandy beach facing the ocean proper (outer beach), a sandy beach on the mainland side of a barrier island (inner beach), and a small mudflat adjacent to a Spartina alterniflora salt marsh. We were able to identify several microhabitats on the outer beach and mudflat. Most species fed in more than one habitat, but only two, Charadrius semipalmatus and Calidris canutus, used all three habitats regularly. Within habitats, most species exhibited strong preferences for the wettest areas, but we found differences among species in degrees of preference. The least amount of partitioning occurred on the inner beach, where birds crowded into a small zone near the waters edge and had frequent agonistic encounters suggesting intense competition. Shorebird feeding activity was partly a function of tide time: each habitat had a characteristic temporal pattern of use by shorebirds related to tide time rather than diel time; within habitats, we found species-characteristic feeding activity rhythms that were also a function of tide time. Feeding by most species peaked during the first 2 hours after low tide on the outer beach and mudflat. The results are discussed in terms of feeding strategies and interspecific competition.-Department of Biology, Livingston College, Rutgers University, New Brunswick, New Jersey 08903 (Burger, Chase); National Fish and Wildlife Laboratory, National Museum of Natural History, Washington, D.C. 20560 (Howe); and Institute of Animal Behavior, Rutgers University, Newark, New Jersey 07102 (Hahn). Present address of Chase: Department of Biology, Barnard College, New York, N.Y. 10027. Accepted 11 March 1977. (This paper was subsidized by the Migratory Bird Program, U.S. Fish and Wildlife Service.) ALTHOUGH usually solitary on their breeding grounds, migrating shorebirds (Charadrii) often form large, mixed-species aggregations that feed along coastal beaches, mudflats, and marshes. These concentrations of shorebirds result in high population densities in prime feeding areas (Recher and Recher 1969). As these habitats are effectively two-dimensional, spatial segregation of flock members can only occur in a horizontal plane. Increased density may lead to more intense competition for space, resulting in more frequent aggressive interactions and/or niche partitioning. Moreover the cyclic tidal inundation of mudflats and beaches causes changes both in the available feeding space and in the diversity and availability of prey items. Shorebirds respond to these changes by moving continually from one foraging area to another. Studies of ecology of migrating and wintering shorebirds have dealt primarily with feeding methods and rates (Goss-Custard 1969, Ashmole 1970, Burton 1972, Baker and Baker 1973, Baker 1974), feeding dispersions (Goss-Custard 1970a), prey densities (Bengtson and Svensson 1968, Brooks 1967, Goss-Custard 1970b), feeding ecology (Recher 1966, Thomas and Dartnall 1971, Holmes 1966, Holmes and Pitelka 1968), and aggressive behavior (Hamilton 1959, Recher and Recher 1969). Most of these studies stress behavior and diet as related to prey availability or broader ecological considerations. Collectively, most data suggest that shorebird species overlap broadly in their diets and feeding habitats. Competitive exclusion may be avoided because species move from point to point without fully exploiting the available food reserves (Recher 1966). Some studies have also identified patterns of niche partitioning with respect to foods, feeding methods, 743 The Auk 94: 743-758. October 1977 This content downloaded from 157.55.39.211 on Tue, 09 Aug 2016 05:06:27 UTC All use subject to http://about.jstor.org/terms 744 BURGER ET AL. [Auk, Vol. 94

EFFECTS OF LEAD ON BIRDS (LARIDAE): A REVIEW OF LABORATORY AND FIELD STUDIES

Lead is one of the most common metals in contaminated ecosystems. Although lead poisoning and mortality have long been known, little is known of the behavioral effects produced by low levels of lead in wild animals. Herein a 15-yr research program on the behavioral effects of lead using herring gulls (Larus argentatus) and common terns (Sterna hirundo), referred to as larids, as models is reviewed. The doses used in laboratory studies were sufficient to produce lead concentrations in feathers that were equivalent to those found in some birds living in the wild. The exposure consisted of a single or multiple intraperitoneal (ip) injection of lead acetate. Both dose and day of exposure influenced behavioral development in young larids, with most effects increasing with dose, and decreasing with age. Low-level lead affected growth, locomotion, balance, food begging, feeding, thermoregulation, depth perception, and individual recognition in laboratory and in wild birds. The accuracy of individual recognition was most affected by lead exposure from 2 to 6 d of age; exposure at 12 d did not affect accuracy, but it delayed response time significantly. Behavioral deficits observed in lead-injected young in the wild were similar to those observed in the laboratory, except that recovery was more complete by fledging than it was in laboratory-raised chicks. Further, parents in the wild were able to provision lead-exposed chicks sufficiently so that they fledged at similar weights as control chicks, a feat that is difficult to achieve in the laboratory. The lead-induced behavioral deficits observed in the laboratory and in the wild are sufficient to affect growth and survival in wild herring gulls. Lead treatment altered the expression of cell adhesion molecules (CAMs), which play a crucial role in the formation and deployment of neurons in the developing brain. The timing and sequencing of CAM expression is critical to normal development, and the different consequences of lead exposure at different ages may be related to interference at different points in the sequence.

A 20-YR STUDY DOCUMENTING THE RELATIONSHIP BETWEEN TURTLE DECLINE AND HUMAN RECREATION'

This study documents the detrimental effects of human recreation on the North American wood turtle (Clemmys insculpta) in Connecticut. We chronicled the dy- namics of two allopatric wood turtle populations in a protected southern New England wildlife reserve for 20 yr (1974-1993). Both wood turtle populations were reproductively isolated from one another, physically separated -100 yr ago when a 1.5 km long human- made pond was constructed. We conducted a mark-and-recapture study on a 1000-ha section restricted, and the quality of the air and water were constant. The wood turtle populations remained stable when people were denied access to the property. When this area was opened to human recreation (hiking, fishing) the two discrete wood turtle populations declined steadily; the total number of turtles in both populations declined by 100% in 10 yr. As wilderness areas become mixed-use recreation areas, wood turtle populations may suffer. We conclude that without proper management, the increasing recreational use of parks, reservoirs, and wildlife reserves will adversely affect the long-term survival of the North American wood turtle.