Allen T. Rutberg

The evolution of monogamy in primates

The evolution of primate monogamy is described as an ordered sequence of choices by generalized, hypothetical females and males. Females first choose whether or not to associate with other females. Predators encourage gregariousness in diurnal primates; however, nocturnality or scarce and evenly distributed food supplies may enforce separation. A testable group size model based on food patch size is developed and qualitatively supported. If females choose solitude, males then choose either to defend a single female and invest in her offspring, or to compete with other males for access to several females, usually by defending a territory or establishing dominance over the home ranges of several females. The decision rests on the defensibility of females and on the availability of an effective form of male parental investment. Both of these factors are dependent on local female population density. A model is developed that assumes that territorial defense is the principal form of male parental investment, and it predicts that monogamy should occur at intermediate densities: at high densities, males should switch to defense of multiple females, and at low densities there is no investment value in male territorial defense. The model is shown to be only partly adequate. Variation in local population densities prevents the establishment of obligate monogamy through territoriality in small monkeys, since male territorial behavior is inconsistent over the long run. Here, carrying of offspring by males can succeed territoriality, providing an effective and reliable form of parental investment to maintain the pair bond in the face of population fluctuations and changes in group structures. This hypothesis is supported by the scarcity of obligate monogamy among the prosimians, which frequently do not carry their young.

Birth Synchrony in American Bison (Bison bison): Response to Predation or Season?

Calving of American bison was observed at the National Bison Range, Montana, in 1982. Approximately 80% of the calves were born in the last week of April and first 2 weeks of May. During calving, cow-calf pairs grouped preferentially with other cow-calf pairs rather than with cows without calves. Because of their open-country habit and lack of group defense, bison are well-suited for application of Estes (1976) predator confusion and saturation hypothesis of reproductive synchrony. However, comparison shows that the length of bison calving seasons is fairly typical for temperate zone ungulates. Although bison calves are highly precocious, bison do not show the calving aggregations predicted by the anti-predator hypothesis. Thus, climatic factors appear to be the best explanation of breeding synchrony in bison.

Effects of immunocontraception on a suburban population of white-tailed deer Odocoileus virginianus

Abstract Abundant populations of white-tailed deer ( Odocoileus virginianus ) in North America have altered the structure of some forest communities and caused serious conflicts with farmers, gardeners, and motorists, encouraging the search for novel techniques to control populations of deer and other wildlife. We administered the porcine zona pellucida (PZP) immunocontraceptive vaccine to female white-tailed deer living on the 233-ha campus of the National Institute of Standards and Technology (NIST) in Gaithersburg, Maryland, USA. Although some tested PZP preparations proved more effective than others, the number of fawns produced per female was significantly lower in treated than untreated females. Following the onset of contraceptive treatments, the population declined by an average of 7.9% per year, and population declines were larger following years when a higher proportion of females was treated. High mortality due largely to deer–vehicle collisions and low population fertility associated with high deer densities facilitated the observed population decline.

Immunocontraception in Wild Horses: One Inoculation Provides Two Years of Infertility

Abstract Previous studies reported one year of contraception associated with a 1-injection porcine zona pellucida (PZP) vaccine. We have subsequently determined contraceptive effectiveness of a presumptive 1-injection, 2-year-duration PZP vaccine in free-roaming wild horses (Equus caballus) in Nevada, USA. In January 2000, we captured, freeze-branded, treated, and subsequently released 96 adult females that received 1) a primary dose of vaccine emulsion consisting of aqueous PZP and Freunds Complete Adjuvant, and 2) booster doses of PZP and adjuvant in controlled-release polymer pellets. We determined PZP release characteristics of pellets in vitro, prior to field use. We determined reproductive success in treated and untreated females through October 2004 via measurement of estrone sulfate and progesterone metabolites in fresh feces collected from the ground and by twice-annual foal counts. Among treated females, annual reproductive success from 2001 though 2004 sequentially was 5.9%, 14.0%, 32.0%, and 47.5%. Untreated females showed average reproductive success of 53.8 ± 1.3% across this period. This study revealed that: 1) PZP acted as an effective contraceptive for 2 years posttreatment; 2) some residual contraceptive effect remained in year 3; and 3) fertility returned to control levels by year 4 posttreatment. It appears that controlled-release technology can replace both the second (1-month) and annual booster injection of PZP vaccine, thereby decreasing cost and increasing efficiency of use of this vaccine in wild horse management.

Controlled-release components of PZP contraceptive vaccine extend duration of infertility

Successful immunocontraception of wildlife relying on repeated access to individuals for boosters has highlighted the need to incorporate primer and booster immunisations into one injection. We have investigated use of controlled-release polymers (lactide–glycolide) in small pellets to provide delayed in vivo delivery of booster porcine zona pellucida (PZP) antigen and adjuvant. This report reviews pellet-making methodology, in vitro testing of controlled-release pellets and in vivo effects of controlled-release PZP vaccine. We assessed 3 different manufacturing approaches for producing reliable, cost-effective pellets: (1) polymer melting and extrusion; (2) solvent evaporation from polymer solution; and (3) punch and die polymer moulding. In vitro testing of release patterns of controlled-release formulations, towards development of a 3-year duration vaccine, provided estimates for in vivo use of pellet preparations. These in vitro studies demonstrated protein release delay up to 22 months using 100% l-lactide or polycaprolactone polymers. For in vivo tests, pellets (1-, 3-, and 12-month release delay) serving as boosters were administered intramuscularly with PZP/adjuvant liquid primer to wild horses (Equus caballus), white-tailed deer (Odocoileus virginanus) and African elephants (Loxodonta africana). Horse field studies assessed fertility via offspring counts and/or faecal-hormone pregnancy testing. Treatment decreased fertility 5.3–9.3-fold in Year 1 and 3.6-fold in Year 2. In preliminary testing in deer, offspring counts revealed treatment-associated fertility reduction of 7.1-fold Year 1 and 3.3-fold Year 2. In elephants, treatment elevated anti-PZP titres 4.5–6.9-fold from pretreatment (no fertility data).

Immunocontraception in feral horses: One inoculation provides one year of infertility

We determined contraceptive effectiveness of a 1-inoculation, 1-year porcine zona pellucida (PZP) vaccine in free-roaming feral horses (Equus caballus) in Nevada. We captured, freeze-branded, treated, and subsequently released 267 adult feral mares given (1) 2 inoculations (13-17 days apart) of vaccine emulsion consisting of aqueous PZP and Freunds Complete Adjuvant (FCA; injection 1) or Freunds Incomplete Adjuvant (FIA; injection 2), (2) same 2 inoculations as in (1) except also containing a carbomer adjuvant in inoculation 1, or (3) a single inoculation of an emulsion of PZP and FCA containing a second dose of PZP and carbomer adjuvant in controlled-release polymer microspheres. We administered inoculations in January 1996, and monitored the mares via fecal analysis for pregnancy and via ground survey for foal production through October 1997. We determined pregnancy via measurement of estrone sulfate and progesterone metabolites in fresh feces collected from the ground. Among 2-inoculation mares, reproductive success across 1 year was 12.8% (carbomer adjuvant absent) and 10.6% (carbomer adjuvant present). In mares given 1 injection containing microspheres, reproductive success was 11.3%. The concurrent rate in 72 untreated mares was 62.5%. This study revealed marked and equivalent 1-year contraceptive efficacy in 1-and 2-inoculation PZP vaccine, indicating that controlled-release technology can replace a second inoculation and thereby increase PZP vaccine cost effectiveness and potential for use in feral horse management.

Population-level effects of immunocontraception in white-tailed deer (Odocoileus virginianus)

In North America, dense populations of white-tailed deer (Odocoileus virginianus) in suburbs, cities and towns have stimulated a search for new population-management tools. Most research on deer contraception has focused on the safety and efficacy of immunocontraceptive vaccines, but few studies have examined population-level effects. We report here results from two long-term studies of population effects of the porcine zona pellucida (PZP) immunocontraceptive vaccine, at the National Institute of Standards and Technology (NIST), Gaithersburg, Maryland, USA, and at Fire Island National Seashore (FIIS), New York, USA. Annual population change at NIST was strongly correlated with population fertility (rP = 0.82, P = 0.001); when population fertility at NIST dropped below 0.40 fawns per female, the population declined. Contraceptive treatments at NIST were associated with a 27% decline in population between 1997 and 2002, and fluctuated thereafter with the effectiveness of contraceptive treatments. In the most intensively treated segment of FIIS, deer population density declined by ~58% between 1997 and 2006. These studies demonstrate that, in principle, contraception can significantly reduce population size. Its usefulness as a management tool will depend on vaccine effectiveness, accessibility of deer for treatment, and site-specific birth, death, immigration, and emigration rates.

Why State Agencies Should Not Advocate Hunting or Trapping

Representatives of state wildlife agencies commonly advocate hunting and trapping. For at least three reasons, they should not do so. First, aggressive advocacy of lethal control of wildlife promotes destructive attitudes about nature. Advocacy of lethal control feeds the predispositions of many urban residents to view local wildlife as pests to be exterminated. Second, advocacy of hunting and trapping undermines agency credibility. Regardless of personal integrity, the budgetary dependency of state wildlife agencies on hunting and trapping license fees automatically raises concerns about their ability to act fairly in the public interest. Third, advocacy of hunting and trapping fails to address the most serious problems facing wildlife today. Defending hunting and trapping interests diverts agency resources, funding, and attention from the more serious issue of protecting habitat. Promoting compassion towards animals is more likely to build widespread public support for wildlife and habitat protection than is advocacy of lethal control.

Shifts in Attitudes Toward Coyotes on the Urbanized East Coast: The Cape Cod Experience, 2005–2012

The migration of coyotes to northeastern United States since the mid-20th century has increased human–coyote interactions. This article offers insights into the evolution of attitudes toward Eastern coyotes by analyzing survey data from voters on Cape Cod, Massachusetts in 2005 and 2012. Responses were obtained in a region where familiarity and conflict with coyotes was high. The data supported growing acceptance of coyotes and increased opposition to lethal control. While previous research has found women to feel more negative toward and fearful of large carnivores, in this study gender differences in acceptance and fear of coyotes diminished with time. Greater opposition among women to lethal interventions persisted. Future studies should examine the gender and geographic dimensions of attitudinal change to more fully understand attitudes toward wildlife in urbanized environments.

MANAGING WILDLIFE WITH CONTRACEPTION: WHY IS IT TAKING SO LONG?

Abstract: Biologists have been testing wildlife contraceptives in the field for nearly a half century. Although effective new contraceptive agents have been identified, new delivery technologies developed, and some success with population management demonstrated, progress in this area should be further along. Why is it taking so long? First, the task is complex. Most drugs and vaccines fail in development. The technical leaps from in vitro to in vivo, from controlled studies to field studies, from effectiveness in individuals to management of populations, are all formidable and frequent failures are inevitable. Testing the long-acting contraceptives required for successful population management demands experiments that take 3–5 yr to complete. Development of wildlife contraceptives has been further hampered by the lack of large-scale investment and the complex and shifting regulatory landscape that often greets novel enterprises. But there has also been focused resistance to the implementation of wildlife contraceptive studies and to the dissemination of results such studies have produced. This phenomenon, which sociologists label “socially constructed ignorance,” has taken a variety of forms including denial of research permits, omission from research reports and management documents, and repetition of misleading or false information in public forums and the media. The persistence and effectiveness of this social resistance suggest that the ethical foundation of wildlife contraception is incomplete. As the institutional affiliations of participants of the 7th International Conference on Fertility Control for Wildlife confirmed, wildlife contraception has its ethical roots in the animal welfare and integrated pest-management communities. Absent from the discussion are the conservation community and the values they represent. To secure societal acceptance of wildlife contraception as a management technique, researchers and advocates for wildlife contraception must address conservation issues and build an ethical foundation that balances concern for individual animals and human needs with concern for the health of biologic communities.