Seasonal Patterns Of Mortality Research Articles

Differential seasonal mortality of the sexes in willow ptarmigan Lagopus lagopus in northern British Columbia, Canada

We assessed sex ratio, annual survival rates and patterns of seasonal mortality of female and male willow ptarmigan Lagopus lagopus in northwestern British Columbia. Annual sex ratio of birds on the breeding area did not statistically differ from a 1:1 ratio over eight years, although in six of the eight years males were more numerous. Over eight years, annual survival, based on return rates of banded birds, was 41–63% for males and 30–54% for females. We analysed seasonal patterns of mortality using radio‐tagged birds. During four springs and summers, female survival varied from 74 to 97%. They suffered the highest mortality during late prelaying, incubation and pre‐fledging brood rearing periods, and most were killed by raptors. Broodless females survived better (100%) than females accompanied by broods (77%). No radio‐tagged males died during two breeding seasons. Survival for both sexes was lower in autumn/winter (40–60%) than in spring/summer (75–100%). In autumn, the highest mortality for both sexes occurred during the late brood rearing and winter moult periods, coinciding with the autumn raptor migration. Both sexes had similar mortality rates over winter, despite separating by habitat. Another peak in male mortality occurred in late winter/early spring during the period of transient territoriality, whereas no females were killed during this time. From 1.4 to 3 times as many males as females were killed by hunters. Higher mortality of males during the hunting season and in late winter may balance the higher mortality of females during the breeding season, resulting in a breeding sex ratio that is close to unity.

SEASONAL VARIATION IN DIRECT OBSTETRIC MORTALITY IN RURAL SENEGAL: ROLE OF MALARIA?

We explore a possible link between malaria and maternal death in a rural area of Senegal by assessing the seasonal pattern of maternal mortality by cause and examining whether this pattern coincides with the malaria season. Overall mortality in women 15-49 years of age did not differ by season, while maternal and direct obstetric deaths were significantly more frequent during the rainy/malaria season than during the rest of the year, even after adjusting for place of delivery.

Mortality patterns, 1993-98, in a rural area of Burkina Faso, West Africa, based on the Nouna demographic surveillance system.

The Nouna demographic surveillance system database was analysed for the period 1993-98. Basic demographic parameters, age-specific and age-standardized mortality rates were calculated and a seasonal variation in mortality was analysed. Poisson regression was used to model the calculated mortality rates and to investigate the seasonal mortality pattern. Both the population distribution by age and the mortality rates reflect a typical pattern of population structures and total mortality in rural Africa as a whole: high childhood mortality and a young population (about 60% are up to age 25; about 10% above age 64). We identified a significant seasonal pattern with highest mortality rates in February. Demographic surveillance systems in Africa provide a viable method for the collection of reliable data on vital events in rural Africa and should therefore be established and supported.

Decline of infant and child mortality rates in rural Senegal over a 37-year period (1963-1999).

In spite of an improving trend, childhood mortality in rural sub-Saharan Africa remains high and has recently risen in some countries. The factors associated with the long-term decline in childhood mortality are poorly known, due to a lack of data. A Senegalese rural population has been under demographic surveillance since 1963. Infant and under-5 mortality rates were calculated for different periods to generate a long-term trend in childhood mortality. Evolution of age and seasonal patterns of mortality were observed. During the observation period (1963-1999), infant and under-5 mortality rates decreased from 223 per thousand to 80 per thousand and 485 per thousand to 213 per thousand , respectively, with a constant annual rate of decline in the probability of dying since the 1960s (-3.7% and -3.1%, respectively). The age pattern of the under-5 mortality changed drastically, with a large decrease in the death rate between 6 and 24 months of age (from 321 per thousand to 87 per thousand ). This change took place during the 1970s. The seasonal variation, characterized by a greater proportion of deaths during the rainy season, was very marked during the 1960s, then decreased during the 1980s but it has tended to increase again in the 1990s, particularly among children 1-4 years old. This study confirms the long-term trend of decrease in child mortality in rural West Africa. Historical knowledge on healthcare developments suggests that immunizations have contributed to the decrease and the change in the age pattern. The re-emergence of malaria seems the most likely explanation for the recent rebound in seasonal variation. Attention to immunization and malaria should continue to be a priority.

Seasonal pattern of early mortality and infectious complications in liver transplant recipients.

Seasonal variation has been documented in the frequency and attributable mortality of a number of medical illnesses and infections in the nontransplantation setting. Whether similar trends exist in transplant recipients is not known. Seasonal rates of overall and early mortality and contributory variables stratified by season were assessed in 190 consecutive liver transplant recipients who underwent transplantation over a 10-year period. The frequency of infectious complications and rejection was also assessed and stratified by season of transplantation. Early (deaths occurring in the first year posttransplantation), but not overall, mortality correlated significantly with seasonality. Of patients with early mortality, 43% (13 of 30 patients) died in winter; 23% (7 of 30 patients), in spring; 13% (4 of 30 patients), in summer; and 20% (6 of 30 patients), in fall. The frequency of deaths in winter was significantly greater than for all other seasons (P = .022). The high wintertime mortality could not be explained by previously recognized risk factors portending a poor outcome, e.g., United Network for Organ Sharing status, Child-Pugh score, surgical time, blood loss, pretransplantation and posttransplantation dialysis, infections, rejection, or increased immunosuppression. Strong trends toward a higher rate of cytomegalovirus disease in patients who underwent transplantation in fall (P = .09) and bacterial infections in those who underwent transplantation in winter were documented (P = .09). There was no correlation between seasonality and rejection. Early mortality in winter in liver transplant recipients was significantly greater than if the deaths were totally random. Whether the seasonal clustering of deaths and infections is triggered by respiratory viruses, yet unrecognized viruses, or unknown exogenous factors remains to be determined.

Demography and sexual size dimorphism in northern water snakes, Nerodia sipedon

We used data from a 9-year mark-recapture study to determine whether demographic factors could explain female-biased sexual size dimorphism in northern water snakes (Nerodia sipedon). Most males reached sexual maturity at 3 years of age, while most females delayed maturity for an additional year. Female survivorship was not significantly lower than that of males, despite the fact that females grow as much as four times faster than males. Among females, survivorship increased until maturity and decreased thereafter, suggesting a survival cost to reproduction. Life-table calculations indicated that the increase in both survival rates and fecundity with body size made 3 years the optimal age for females to reach sexual maturity. However, if females were not large enough at 3 years of age, their best strategy was to mature the following year. Seasonal patterns of mortality suggest that mating imposes a high mortality cost on males. Intermediate-sized males survived slightly but not significantly better than small and large males. This slight survival advantage of intermediate-sized males was not sufficient to explain why males are so much smaller than females. Therefore other selective factors must be responsible for males retaining a small size. A reproductive advantage associated with small size seems the most likely possibility.

Physiological ecology of a tropical dragon, Lophognathus temporalis

Lophognathus temporalis is an arboreal lizard from the wet–dry tropics of Australia. During the wet season the field metabolic rate (FMR) of the lizards was 209 kJ kg−1 d−1, but during the dry season FMR was only 62 kJ kg−1 d−1. Similarly, water flux decreased from 73.6 mL kg−1 d−1 in the wet season to 18.5 mL kg−1 d−1 in the dry season. Body temperatures (Tb) were significantly lower in the dry season, and operative temperatures, calculated by incorporating microclimatic data with characteristics of the lizards, indicated that the seasonal shift was due to changes in thermoregulatory behaviour rather than limitations of the thermal environment. By combining field measurements of Tb and FMR with laboratory measurements of standard metabolic rate over a range of Tb, we were able to subdivide the FMR into its components and to determine which factors contributed to the seasonal reduction in energy expenditure. During the dry season, lizards used 147 kJ kg−1 d−1 less energy than during the wet season, and 24% of this decrease was estimated to be due to the passive effects of lower nighttime Tb, 14% was due to the active selection of lower daytime Tb, 27% was due to the physiological shift to lower standard metabolic rates, and 35% was due to reduced activity in the dry season. Although the population size remained relatively constant (107 lizards ha−1 during the wet season and 125 lizards ha−1 during the dry season), the population structure changed, reflecting the seasonal patterns of recruitment and mortality. The number of lizards active at any one time was much lower in the dry season, reflecting the lower levels of activity in this season. The energy expenditure of the population of L. temporalis was 612 kJ ha−1 d−1 during the wet season and 113 kJ ha−1 d−1 during the dry season.

Seasonal variation in stroke mortality rates

To identify possible contributors to the seasonal variation in stroke mortality. Stroke and respiratory disease mortality rates were calculated from vital statistics and census data for the United States from 1938 to 1988. State-specific average temperatures by month were derived from data obtained from the National Climatic Data Center for 1938 to 1987. Each time series was decomposed into a trend, a seasonal effect, and a residual effect. Multiple regression was used to fit both a trend and a seasonal harmonic series. Cross-correlation was used to assess the relationship between the residual time series. There is a strong and consistent seasonal pattern of high stroke and respiratory disease mortality in the colder winter months. Stroke mortality was significantly and independently both positively associated with respiratory disease mortality and inversely associated with temperature. The sharp initial increases in both respiratory disease and stroke mortality in the late fall and early winter are synchronous, and the amplitudes are strongly associated, except for a saturation effect with extreme respiratory disease amplitudes. Seasonal change in stroke mortality is associated with seasonal variation in both respiratory disease and temperature. Respiratory disease and temperature may influence stroke mortality nonspuriously by affecting stroke case fatality, incidence, or both.

The dangers of leaving home: dispersal and mortality in snakes

For animal populations in many parts of the world, direct (albeit often accidental) killing by humans may be a significant source of mortality. Many snakes are killed by people (especially by automobiles) every year, but the determinants of a snake's vulnerability to anthropogenic mortality (and thus, patterns of mortality with respect to sex, age and season) are poorly known. We present data on 652 French snakes of six species ( Coluber viridiflavus, Elaphe longissima, Natrix maura, N. natrix, Vipera aspis, V. berus) killed either by natural predators, domestic animals or humans (including roadkills). We used information on seasonal patterns of mortality (plus information on population structure from 338 captures of live snakes) to test the hypothesis that snakes are killed mostly when they disperse from their usual home ranges. This hypothesis generates several falsifiable predictions on the expected correlates of mortality rates; most of these predictions are supported by our data. For example, young-of-the-year snakes are killed primarily in the period immediately after hatching (while they disperse); subadults (which are sedentary) generally experience low mortality rates; adult males are killed mainly during the mating season (especially in species where mate-searching males travel widely); and adult females in oviparous species are killed during their egg-laying migrations. Relative to population density, species that use frequent long-distance movements in foraging experience higher mortality than sedentary ambush foragers. In one species ( E. longissima), larger males are more at risk. The success of these predictions suggests that movement patterns of snakes may offer valuable indices of their vulnerability to direct anthropogenic mortality.

Demography and sexual size dimorphism in northern water snakes, <i>Nerodia sipedon</i>

We used data from a 9-year mark-recapture study to determine whether demographic factors could explain female-biased sexual size dimorphism in northern water snakes (Nerodia sipedon). Most males reached sexual maturity at 3 years of age, while most females delayed maturity for an additional year. Female survivorship was not significantly lower than that of males, despite the fact that females grow as much as four times faster than males. Among females, survivorship increased until maturity and decreased thereafter, suggesting a survival cost to reproduction. Life-table calculations indicated that the increase in both survival rates and fecundity with body size made 3 years the optimal age for females to reach sexual maturity. However, if females were not large enough at 3 years of age, their best strategy was to mature the following year. Seasonal patterns of mortality suggest that mating imposes a high mortality cost on males. Intermediate-sized males survived slightly but not significantly better than s...

Patterns of Conception, Natality, and Mortality from Midwestern Cemeteries: A Sociological Analysis of Historical Data

Our research demonstrates the potential of cemeteries data for sociology and contributes to a greater understanding of demographic and social patterns characterizing the Midwest since its Euramerican settlement. We examine data from ten cemeteries (2,021 burials) spanning the 1830s–1980s in east-central Illinois. Seasonal conception patterns reflect winter and spring peaks, with indication of the spring peak dissipating more recently. Seasonal mortality patterns show a tendency for younger people to die in late summer and older people to die in late winter. Contrary to national patterns, we found female deaths exceeding male deaths in the 10–64 age group. As expressions of gender bias, females are disproportionately identified on gravestones in terms of familial relationships. Of the different cemetery types surveyed (1 family, 4 neighborhood, 2 community, 3 church), only the church cemeteries continue to be used, suggesting a sectarian role in preserving otherwise declining communities.

Geographical and seasonal patterns of mortality in red grouse Lagopus lagopus scoticus populations

Corpses of red grouse Lagopus lagopus scoticus were collected monthly from 10, 1‐km2 study areas on managed grouse moorland for a period of 10 years. Six of the study areas were located in Scotland and four in Northern England. A greater number of corpses were found on the Scottish study areas than on the English and compositional analysis identified the relative importance of death through parasitism in England. Stoat Mustela erminea kills were more prevalent in England but fox Vulpes vulpes and large raptors were more important in Scotland. Predators were more abundant in Scotland and frequency of sightings positively correlated with number of kills between study areas. There was a seasonal peak in mortality in spring.

Effects of Predator Foraging Behavior on Patterns of Prey Mortality in Marine Soft Bottoms

This study links spatial and seasonal patterns of mortality of the hard clam, Mercenaria mercenaria (L.), in marine soft bottoms with the predation rates and habitat use of its main predator, the blue crab, Callinectes sapidus Rathbun. Patterns of predation on tethered juvenile clams exposed to the natural assemblage of predators were compared among different habitat types in fall and summer. Between-habitat patterns of predation on clams varied with season. In fall, predation on tethered clams was greater in subtidal sand bottoms and just inside the edge of intertidal salt marshes than in intertidal sand flats. In summer, predation on clams was similar in all habitats. Experiments conducted in field enclosures showed that: (a) individual crabs spent more time in the salt marsh habitat than in intertidal sand flats; (b) crab individuals placed in a sand bottom habitat had greater predation rates in high-density prey patches than in low-density patches; (c) individuals had greater predation rates in prey patches located just inside the edge of salt marshes than in intertidal sand flats, when prey density was held constant between the two habitats; (d) at intermediate and high crab densities predation mortality of clams was similar between vegetated and unvegetated habitats; (e) both individual crabs and groups of crabs consumed similar numbers of clams in the two habitat types when large predatory birds (mainly various species of terns, Sterna spp., herring gulls, Larus argentatus Coues, and ring-billed gulls, L. delawarensis Ord) were excluded from enclosures, but the crabs consumed more clams in the salt marsh than in the sand flat habitat in control enclosures where birds were not excluded. In the fall, when Herring and Ring-billed Gulls were abundant in the study area, preference by blue crabs for safer and more profitable habitats may explain the greater predation on clams in salt marshes than in intertidal sand flats. In the summer, when Herring and Ring-billed Gulls were rare and crab densities are 1.5–3 times greater than in the fall, competition with conspecifics may have caused crabs to disperse and feed in intertidal flats and may explain the general lack of differences in predation intensity among habitat types observed in the summer. Thus, patterns of predation and habitat use by blue crabs appeared to explain between-habitat and seasonal differences in predation mortality of clams. Focusing on the variation in the feeding rates of individual predators in response to external conditions can produce the mechanistic understanding of spatial and seasonal patterns of predation needed to understand and better predict the processes that structure benthic marine communities.

EFFECTS OF PREDATOR FORAGING BEHAVIOR ON PATTERNS OF PREY MORTALITY IN MARINE SOFT BOTTOMS

This study links spatial and seasonal patterns of mortality of the hard clam, Mercenaria mercenaria (L.), in marine soft bottoms with the predation rates and habitat use of its main predator, the blue crab, Callinectes sapidus Rathbun. Patterns of predation on tethered juvenile clams exposed to the natural assemblage of predators were compared among different habitat types in fall and summer. Between-habitat patterns of predation on clams varied with season. In fall, predation on tethered clams was greater in subtidal sand bottoms and just inside the edge of intertidal salt marshes than in intertidal sand flats. In summer, predation on clams was similar in all habitats. Experiments conducted in field enclosures showed that: (a) individual crabs spent more time in the salt marsh habitat than in intertidal sand flats; (b) crab individuals placed in a sand bottom habitat had greater predation rates in high-density prey patches than in low-density patches; (c) individuals had greater predation rates in prey patches located just inside the edge of salt marshes than in intertidal sand flats, when prey density was held constant between the two habitats; (d) at intermediate and high crab densities predation mortality of clams was similar between vegetated and unvegetated habitats; (e) both individual crabs and groups of crabs consumed similar numbers of clams in the two habitat types when large predatory birds (mainly various species of terns, Sterna spp., herring gulls, Larus argentatus Coues, and ring-billed gulls, L. delawarensis Ord) were excluded from enclosures, but the crabs consumed more clams in the salt marsh than in the sand flat habitat in control enclosures where birds were not excluded. In the fall, when Herring and Ring-billed Gulls were abundant in the study area, preference by blue crabs for safer and more profitable habitats may explain the greater predation on clams in salt marshes than in intertidal sand flats. In the summer, when Herring and Ring-billed Gulls were rare and crab densities are 1.5-3 times greater than in the fall, competition with conspecifics may have caused crabs to disperse and feed in intertidal flats and may explain the general lack of differences in predation intensity among habitat types observed in the summer. Thus, patterns of predation and habitat use by blue crabs appeared to explain between-habitat and seasonal differences in predation mortality of clams. Fo- cusing on the variation in the feeding rates of individual predators in response to external conditions can produce the mechanistic understanding of spatial and seasonal patterns of predation needed to understand and better predict the processes that structure benthic marine communities.

Seasonal patterns in the mortality of <I>Daphnia </I> species in a shallow lake

To assess the impact of predation by young-of-the-year (0+) fish on the population dynamics of Daphnia species, we made independent estimations of the mortality of Daphnia species during the year, and of the predation pressure exerted by the juvenile fish. Mortality of daphnids was computed using a model that allowed us to differentiate between different size- classes, while total fish consumption was estimated from the temperature-dependent daily weight increase and the population development of the 0+ fish. The predation pressure on the different size-classes of Daphnia species was estimated by combining the total fish consumption with estimates of the selective feeding behaviour of the fish. To make the estimates of fish consumption independent of our current (1989-1991) zooplankton data set, we estimated fish species-specific and fish length-dependent selectivity indices on zooplankton using a different data set (1976-1977). Daphnia population densities usually increased in spring and decreased rapidly in early summer. Predation by 0+ fish was not severe enough to explain the large mortality that caused the summer decline; later in the year most of the mortality in the larger size-classes of the daphnids (>1.0 mm) could be explained by fish predation. [KEYWORDS: Young yellow perch; clear-water phase; body size; planktivorous fish; leptodora-kindti; neusiedler-see; eutrophic lake; hyalina leydig; birth-rate; zooplankton]

Communal Cavity Roosting in Green Woodhoopoes: Consequences for Energy Expenditure and the Seasonal Pattern of Mortality

-Green Woodhoopoes (Phoeniculus purpureus) roost in cavities in groups throughout the year. It has been proposed that the energy savings achieved by roosting with conspecifics in a cavity could enable birds in poor body condition to remain normothermic during inclement weather. We tested the hypothesis that woodhoopoes conserve energy by roosting with conspecifics in cavities and found that a woodhoopoe roosting with four conspecifics can reduce its nighttime energy expenditure by 30% or more when the minimum ambient temperature is about 5?C. In areas where nocturnal temperatures sometimes drop below freezing, such energy savings are associated with mortality patterns among adults during winter. Our data support the idea that energy considerations may have been important in the evolution and/or maintenance of sociality in this species. Received 14 August 1992, accepted 25 November 1992. GREEN WOODHOOPOES (Phoeniculus purpureus; also known as Red-billed Woodhoopoes) are cooperative breeders that live in groups of 2 to 12 individuals (Ligon and Ligon 1978). Woodhoopoes obligately roost communally in cavities throughout their range even though they are unable to excavate these holes themselves. This dependence appears critical for their survival by either providing energetic benefits to individuals, protection against predators, or both (Ligon and Ligon 1978, 1988, Ligon et al. 1988, Du Plessis 1989a, b, Williams et al. 1991). The energy savings associated with communal cavity roosting have been implicated as an important driving force in the evolution of sociality in this species (Williams et al. 1991). In an earlier paper, Williams et al. (1991) reported that Green Woodhoopoes maintained normothermic body temperatures at ambient temperatures from -1O? to 40?C. However, birds that were in apparently poor body condition, as judged by their unusually low body mass, exhibited body temperatures slightly below 39?C, even at moderate ambient temperatures. We reasoned that birds in depressed body condition will be unable to thermoregulate at low ambient temperatures, but that they can do so when roosting in cavities with conspecifics. We suggested that I Present address: Department of Physiology, College of Medicine, University of Arizona, Tuscon, Arizona 85724, USA. cavity roosting may be particularly critical to first-year birds, and that it may also be important to adults that have experienced periods of food shortage. In this paper we examine the energetic benefits of Green Woodhoopoes' communal cavity-roosting behavior.

Reproductive ecology of a cleistogamous annual, Impatiens noli‐tangere L., occurring under different environmental conditions

AbstractDemographic and reproductive schedules were compared among five populations of a cleistogamous annual, Impatients noli‐tangere L., occurring in habitats with contrasting moisture and/or light environments. In all populations, flowering extended for 2–3 months during which light environment and mortality changed. Seasonal patterns of growth and mortality were significantly different among the five populations studied. The beginning and duration of flowering and the ratio of chasmogamous flowers to cleistogamous ones were also significantly different among populations. An experiment was conducted under different light conditions (open and closed) to separate the genetic and environmental components of the variation in reproductive traits observed among populations of I. noli‐tangere. Transplanted plants showed significant among‐population variation in flowering time, as is observed in natural populations, suggesting genetic differentiation among populations of this species. On the other hand, the ratio of chasmogamous flowers did not differ among plants transplanted from three populations. Based on these results, the authors suggest that facultative cleistogamy is a conditional strategy under seasonally changing environments.

Les modèles alpins de mortalité infantile

The evidence presented in this article shows that from the mid-18th century up to the early 20th century babies and young children tended to have a more favourable mortality experience in the upland regions of the Alpine crescent than in the adjacent hilly and flat areas. Although several explanations have been advanced, most scholars are inclined to believe that the lower levels of infant mortality displayed by the Alpine area were primarily accounted for by climatic and other environmental factors, which made infants less vulnerable to bronchial and pulmonary disease and lessened the risk of gastro-intestinal disorders. The available evidence also shows, however, that broad differences can be detected across major regional subdivisions, infant mortality rates being markedly higher in the Austrian Alps than in the rest of the Alpine area. Such differences appear to be mainly related to regional variations in infant feeding habits. Some specific features of Alpine seasonal patterns of infant mortality are also discussed. This article ends up with a tentative outline of long-term trends in Alpine infant mortality from the poorly recorded period before 1750 up to the 1950s.

Societal and ecological determinants of urban health: A case study of pre-reproductive mortality in 19th century Gibraltar

A historical based enquiry of colonial Gibraltar at the turn of the 19th century was conducted in order to assess what factors gave rise to residential variation of pre-reproductive mortality. Gibraltar's unusual configuration of a port city, garrison town, and commercial centre at the tip of the Iberian peninsula offers a unique opportunity to examine the interplay of ecology, demographic and socio-economic factors on childhood mortality. Communal living under the patio system and the sharing of essential resources were characteristic features of life on the Rock. Using the residential district as the focus of enquiry, stepwise regression results for the period 1879–1881, designated as a period of ‘low ecological stress’, indicated that the number of gallons of portable water per person captured a significant amount of variability in mortality. During the year 1878, a serious shortfall in rainfall was associated with lower life expectancy, a change in the seasonal pattern of mortality, and elevated rates of deaths attributable to the diarrhea complex. Under this period of ‘high ecological stress’, the percentage of servants in the household, a proxy for wealth/status, proved to be the single most important factor accounting for 46.6% of the variation in the death rate under 15. Analysis of mortality at the patio level revealed that residents of buildings of two household units had lower mortality than residents living in smaller or larger dwellings, particularly in the period of high ecological stress. The complex pattern of mortality at the district and patio level is explained in terms of the development of residential preferences and decentralized nature of vital resources, such as the water support system and food supply.

Mortality of Unfed Nymphal Ixodes dammini (Acari: Ixodidae) in Field Exclosures

Nymphs of the deer tick, Ixodes dammini Spielman, Clifford, Piesman & Corwin, were studied in Westchester County, NY, to determine the seasonal mortality pattern and the potential for unfed nymphs to survive through the active season (May–August). Field-collected nymphal ticks were monitored in field exclosures, which prevented contact with mammals while not restricting habitat choice by ticks. In addition, nymphs were confined in small mesh packages and monitored in the field. In 1989, few (1.3%) ticks placed in exclosures in May–June survived until the end of August. The average mortality rate (proportion of ticks dying per day) in the exclosures was 0.04 ± 0.03 in 1989, 0.048 ± 0.03 in 1990. Ticks placed in mesh packages had 90% mortality after 46 d, 99% after 100 d, and 100% after 300 d. These results indicate that survival through the active season is rare in nymphal I. dammini in Westchester.