I. C. T. Nisbet and Company

North Falmouth, MA, United States

I. C. T. Nisbet and Company

North Falmouth, MA, United States
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Nisbet I.C.T.,I. C. T. Nisbet and Company | Apanius V.,I. C. T. Nisbet and Company
Waterbirds | Year: 2013

Hematocrits were measured in Common Terns (Sterna hirundo) (n = 75) that were exposed to oil from a spill in Buzzards Bay, Massachusetts, USA, in 2003, and that laid eggs 17-39 days following the spill. Comparative data were obtained in three pre-and two post-spill years and from three unoiled reference sites. In non-spill years, annual means of hematocrit varied in parallel with breeding performance. Hematocrits were lower (mean 45.3, n = 75) and more variable in the oil spill year than in non-spill years, and 20% of birds sampled were anemic (hematocrit < 41.7). However, hematocrits were almost as low (mean 46.4, n = 44) in 2002, a year with naturally adverse conditions. In 2002, hematocrits and body-masses were depressed following two storms and recovered in parallel following the storms; hematocrits were positively correlated with body-mass and ambient temperature and negatively correlated with wind speed. In contrast, in 2003 hematocrits were negatively correlated with body-mass and temperature and positively correlated with wind speed. Hematocrits were very low (mean 39.8, n = 15) when birds were first sampled 20-23 days after the spill and recovered toward normal levels by day 39 (mean 49.4, n = 14). Reduced hematocrits can be a useful indicator of sublethal oil intoxication, especially in females, provided that they are not associated with low body-masses or adverse weather. Measuring hematocrits could be useful for rapid screening of populations sublethally exposed to oil.

Nisbet I.C.T.,I. C. T. Nisbet and Company | Wingate D.B.,P.O. Box CR 86 | Szczys P.,Eastern Connecticut State University
Waterbirds | Year: 2010

A small, isolated population of Common Terns (10-30 pairs) has bred at Bermuda since at least the 1920s. In September 2003, a hurricane eliminated all the adult males; only females returned in 2004 and these paired together and laid clutches of threeseven infertile eggs. The breeding population was re-established in 2005-06 by four adult males that had been too young to breed in 2003-04. These males paired with females that were probably young and bred with high success (mean 2.6 fledged chicks/pair) through 2009. Two males apparently each mated with two females to form productive trios. The old females continued to pair together and lay infertile eggs, even though males were raising chicks on the same islets. Consequently, the effective population size at the 'bottleneck' was only four males and four females. Although the population is now increasing rapidly, it remains critically endangered.

Gaston A.J.,Environment Canada | Francis C.M.,Environment Canada | Nisbet I.C.T.,I. C. T. Nisbet and Company
Journal of Field Ornithology | Year: 2013

Use of soft-metal (aluminum alloy) bands on gulls (Laridae) is known to result in high rates of band loss and, as a result, hard-metal (monel, incoloy, or stainless steel) bands are superior for most studies. However, the U.S. Bird Banding Laboratory (BBL) and the Canadian Wildlife Service Bird Banding Office continue to issue soft bands for use on gulls, and the BBL does not make specific recommendations about use of hard bands so many banders continue to use soft bands. For wholly marine species of gulls banded in North America since 1996, ∼20% have been banded with soft bands; the proportion of soft bands used on partially freshwater gulls was ∼70% up to 2009, but has since fallen to 40%. Using hierarchical Bayesian models in program MARK, we analyzed recovery data for three gull species and found that estimates of annual survival rates derived from soft bands (0.68-0.81) were lower than those derived from hard bands (0.85-0.96). Comparison of survival rates of Herring Gulls (Larus argentatus) in the Great Lakes basin and on the Atlantic coast provided no evidence that soft bands last longer in freshwater than saltwater. Band loss compromises many types of studies, including those assessing the possible effects of climate change. We recommend that use of soft bands on gulls be discontinued, and that banders be required to use hard bands on these species in the future. The same consideration applies to other long-lived species, including some waterfowl and all albatrosses, pelicans, cormorants, shearwaters, petrels, terns, shorebirds, and alcids. Use of hard bands should be based on expectations about a species' longevity and evidence of band wear, rather than on whether or not it occurs in saltwater. © 2013 The Authors. Journal of Field Ornithology © 2013 Association of Field Ornithologists.

Szczys P.,Eastern Connecticut State University | Nisbet I.C.T.,I. C. T. Nisbet and Company | Wingate D.B.,P.O. Box CR 86
Conservation Genetics | Year: 2012

Common Terns nesting at Bermuda are isolated by 1,000-4,000 km from other populations of the species around the North Atlantic Ocean. This population experienced a severe demographic bottleneck as a result of a hurricane in 2003 and was subsequently re-established by four males and four females. Using seven microsatellite loci, we compared the genetic diversity of the pre- and post-bottleneck populations, compared the genetic profile of the Bermuda population with those of other populations around the North Atlantic Ocean and mainland Europe, and assessed the potential contribution of immigration to genetic diversity. We found a loss of genetic diversity (number of alleles and heterozygosity) in the post-bottleneck Bermudian population (4. 6-2. 9 and 0. 56-0. 52, respectively). We also report significant differentiation among all sampled locations (global F ST = 0. 16) with no evidence for immigration into Bermuda. Common Terns from the Azores were genetically more similar to those from mainland North America than to those from Bermuda or mainland Europe. Our results suggest that the critically endangered population in Bermuda is genetically distinct and requires continued and enhanced conservation priority. © 2012 Springer Science+Business Media B.V.

Heidinger B.J.,University of Glasgow | Chastel O.,CNRS Chizé Center for Biological Studies | Nisbet I.C.T.,I. C. T. Nisbet and Company | Ketterson E.D.,Indiana University Bloomington
Functional Ecology | Year: 2010

Reproductive success often increases with age; however the mechanisms underlying this commonly observed pattern are poorly understood. One mechanism that may be important is a set of physiological responses (the stress response) that allows organisms to evade and cope with stressors, but often inhibits reproduction. If older parents respond less strongly to stressors than younger parents, this age-related difference in the stress response may contribute to the higher reproductive success that often characterizes older parents. Typically the stress response is measured as an increase in plasma glucocorticoid (CORT) concentration, and we have previously reported that stress-induced CORT levels decline with age in the common tern (Sterna hirundo). Another hormone, prolactin (PRL), has been reported to decrease in response to stressors in breeding birds and is often positively associated with parental behaviour. We predicted that like the CORT stress response, the PRL stress response would also be suppressed with age. To test this prediction, we captured known-age, incubating common terns ranging in age from 3 to 29 years and measured stress-induced changes in PRL and CORT levels within the same individuals. We found that PRL levels decreased less rapidly in response to capture and restraint stress in older than in younger parents. In these same birds, we also found that stress-induced maximum CORT levels decreased with age, which is consistent with what we have previously reported for this species. Measures of PRL and CORT were not, however, correlated within individuals. Taken together, these results support the hypothesis that modulations of both the PRL and CORT stress response are flexible hormonal mechanisms that help to account for the increase in reproductive success that occurs with age. © 2010 The Authors. Journal compilation © 2010 British Ecological Society.

Nisbet I.C.T.,I. C. T. Nisbet and Company | Mostello C.S.,Rabbit Hill Road | Veit R.R.,CUNY - College of Staten Island | Fox J.W.,British Antarctic Survey | Afanasyev V.,British Antarctic Survey
Waterbirds | Year: 2011

Ten geolocators (light-level data loggers) were attached to Common Terns (Sterna hirundo) at a breeding site in the northeastern USA in 2007 and 2008; six were retrieved (five with useful data) in 2008 and 2009. The birds wintered in four discrete areas on the north and east coasts of South America, from Guyana (6-7°N) to northeastern Argentina (36-42°S); three remained within restricted areas for most or all of the winter, whereas two ranged more widely. They left the breeding area at various dates between 1 August and 14 September; three migrated directly from the breeding area while two first moved southwest to stage near Cape Hatteras. All five birds flew directly to the vicinity of Puerto Rico, then moved along the north and east coasts of South America, staging at scattered locations for periods of 3-11 d, before reaching their winter quarters at various dates from 6 September to 26 October. Two birds left their winter quarters on 2 March and 4 April, staged in northern Brazil for 47 and 6 d, then traveled via the Bahamas to reach the breeding site on 1 May. During breeding and post-breeding periods, the birds spent a mean of 7 min each day and virtually no time at night resting on the water, but during the rest of the year they often rested on the water for up to 6 h by day and up to 11 h at night. Leg-mounted geolocators caused several adverse effects but did not reduce survival.

Breton A.R.,Colorado State University | Nisbet I.C.T.,I. C. T. Nisbet and Company | Mostello C.S.,00 Hartwell St. | Hatch J.J.,University of Massachusetts Boston
Ibis | Year: 2014

Dispersal is increasingly recognized as a process of fundamental importance in population dynamics and other aspects of biology. Concurrently, interest in age-dependent effects on survival, including actuarial senescence, has increased, especially in studies of long-lived seabirds. Nevertheless, datasets necessary for studying dispersal and age-dependent effects are few, as these require simultaneous data collection at two or more sites over many years. We conducted a 22-year capture-mark-recapture study of Common Terns Sterna hirundo at three breeding colonies 10-26 km apart in Buzzards Bay, Massachusetts, USA. All birds in the study were of known age (range 2-28 years, median 7 years, n = 3290) and 77% were of known sex. Estimates of adult recapture, survival and breeding dispersal rates were obtained for all age-classes from 2 to 20 years. The model that acquired 100% of the QAICc (Akaike's Information Criterion adjusted for small sample size and overdispersion) weight in our analysis included age-specificity in all parameters but no relationship with sex. Our study may be the first to demonstrate age-specificity in recapture, survival and breeding dispersal rates simultaneously, using a single model. Annual rates of breeding dispersal ranged from <0.01 to 0.27, with a population-weighted mean of 0.065; they decreased with increasing distance between colony sites and, unexpectedly, increased with age. Breeding dispersal did not increase consistently after years with predation on adults or after an attempt to displace birds from an oiled site. Survival rates did not vary among sites or years. Annual adult survival increased from 0.80 in 2-year-old birds to a maximum of approximately 0.88 around age 8 years and then declined to 0.76 at age 20 years, yielding strong evidence for actuarial senescence. The peak annual survival rate of 0.88 is at the low end of other estimates for Common Tern and in the lower part of the range recorded for other terns, but total numbers in the three colonies increased seven-fold during the study. This was part of a slower increase in the regional population, with net immigration into the study colonies. Our results demonstrate the biological significance of breeding dispersal in local population dynamics and age-related effects on survival and dispersal from a metapopulation of a long-lived seabird. © 2014 British Ornithologists' Union.

Hatch J.J.,University of Massachusetts Boston | Nisbet I.C.T.,I.C.T. Nisbet and Company
Ibis | Year: 2011

Manipulation of clutch size during incubation has been used in a number of studies to investigate life-history costs of incubation. We increased or decreased clutches of Common Terns Sterna hirundo during incubation and measured subsequent chick growth and productivity. Our results provide little support for the hypothesis that costs of incubation in Common Terns are substantially affected by the number of eggs incubated. © 2010 The Authors. Journal compilation © 2010 British Ornithologists' Union.

Oswald S.A.,Pennsylvania State University | Nisbet I.C.T.,I.C.T. Nisbet and Co. | Chiaradia A.,Phillip Island Nature Parks | Arnold J.M.,Pennsylvania State University
Methods in Ecology and Evolution | Year: 2012

1. Nonlinear, parametric curve-fitting provides a framework for understanding diverse ecological and evolutionary trends (e.g. growth patterns and seasonal cycles). Currently, parametric curve-fitting requires a priori assumptions of curve trajectories, restricting their use for exploratory analyses. Furthermore, use of analytical techniques [nonlinear least-squares (NLS) and nonlinear mixed-effects models] for complex parametric curves requires efficient choice of starting parameters. 2. We illustrate the new R package FlexParamCurve that automates curve selection and provides tools to analyse nonmonotonic curve data in NLS and nonlinear mixed-effects models. Examples include empirical and simulated data sets for the growth of seabird chicks. 3. By automating curve selection and parameterization during curve-fitting, FlexParamCurve extends current possibilities for parametric analysis in ecological and evolutionary studies. Video. Video © 2012 The Authors. Methods in Ecology and Evolution © 2012 British Ecological Society.

Arnold J.M.,Pennsylvania State University | Nisbet I.C.T.,I.C.T. Nisbet and Company | Oswald S.A.,Pennsylvania State University
Journal of Animal Ecology | Year: 2016

Post-natal growth is an important life-history trait and can be a sensitive indicator of ecological stress. For over 50 years, monotonic (never-decreasing) growth has been viewed as the predominant trajectory of post-natal mass change in most animal species, notably among birds. However, prevailing analytical approaches and energetic constraints may limit detection of non-monotonic (or multiphasic), determinate growth patterns, such as mass recession in birds (weight loss prior to fledging, preceded by overshooting adult mass), which is currently believed to be restricted to few taxa. Energetic surplus and shortfall are widespread conditions that can directly influence the degree of mass overshooting and recession. Thus, we hypothesize that in many species, prevailing energetic constraints force mass change away from a fundamental non-monotonic trajectory to instead follow a monotonic curve. We observed highly non-monotonic, mass change trajectories (overshooting adult mass by up to almost 20%) among common tern Sterna hirundo chicks, a well-studied species long-established as growing monotonically. We quantified the prevalence and magnitude of non-monotonic mass change prior to fledging for 313 common tern chicks that successfully fledged from two discrete populations in multiple years. We used a new approach for analysing non-monotonic curves to examine differences in mass change trajectories between populations under contrasting abiotic (freshwater vs. saltwater) and biotic stresses (low rates of food provisioning). Some degree of mass recession occurred in 73% of all study chicks. Overshooting adult mass followed by extensive mass recession was most prevalent at our freshwater colony, being detected among 34-38% of chicks annually. Non-monotonic trajectories were less marked in populations experiencing ecological stress and among lower quality individuals. Chicks that were provisioned at higher rates were more likely to both overshoot adult mass and experience subsequent mass recession. Our results in common terns provide strong support for the hypothesis that non-monotonic trajectories are the fundamental pattern of mass change but are constrained to be monotonic under energetic shortfall. This justifies future tests of the generality of this hypothesis across a broad range of taxa. We also demonstrate a recent analytical tool that prevents routine fitting of monotonic curves without prior investigation of non-monotonic trends. © 2016 British Ecological Society.

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