Sarah P. Saunders

Female site familiarity increases fledging success in Piping Plovers (Charadrius melodus)

ABSTRACT. Reproductive success commonly improves with age in birds. However, it is difficult to determine whether this phenomenon is due to breeding experience or other age-related factors because most potential explanatory factors are positively correlated. Using a 17-year database, we investigated how age, breeding experience, location experience, and pair-bond experience influenced Piping Plover (Charadrius melodus) reproductive success in the Great Lakes region. Reproductive success was measured as number of offspring fledged per pair for 415 successful nests during 1993–2009. We controlled for individual and site variation with random effects and tested for increased reproductive success associated with age, prior breeding experience, prior location experience, and prior pair-bond experience using generalized linear mixed models. Reproductive success increased with location-specific breeding experience of females and declined when females moved to a new location. After statistically controlling for these effects, we found no additional effect of male age, male experience, or pair experience. Additionally, fledging success declined with later hatching dates, so we examined the relative influence of age and experience on hatch date and determined that older females and males bred earlier. Our results indicate that improvement in reproductive success with age in Piping Plovers has two components: a direct effect of female location experience on fledging success, and an indirect effect of timing of breeding, which leads to greater reproductive success through earlier nesting by older males and females. Actions by resource managers to promote breeding philopatry and successful early nesting attempts may enhance reproductive success of this federally endangered population.

SURVIVAL OF PIPING PLOVER (CHARADRIUS MELODUS) CHICKS IN THE GREAT LAKES REGION

ABSTRACT. The Great Lakes population of Piping Plovers (Charadrius melodus) is federally endangered, numbering between 17 and 71 pairs during 1986–2011. Recovery efforts are diverse, but a major management focus is reduction of predation on eggs and chicks. We evaluated rates and potential causes of mortality for 2,143 chicks from 597 broods at 31 separate breeding sites during 1992–2011. Average daily survival rates of chicks increased from hatch until fledging (∼23 days of age), but this pattern exhibited substantial variation among breeding sites and years, so we included breeding sites and years as random effects in our models. Average (± SE) survival to fledging age was 0.556 ± 0.011. Survival increased with year (1992–2011) and declined with hatching date (28 May–25 July), with seasonal declines becoming more pronounced in recent years. Survival of chicks was reduced by heavy rain (>1 cm) during the first 3 days of life, but <10% of broods were affected. Although site effects were pronounced in the random effects analysis, only one covariate related to nest locations was important: chick survival decreased with proximity of nests to trees. Because broods that hatched earlier in the season had higher survival, management efforts should be focused on finding and protecting nests of early breeding pairs. In addition, because some sites have lower chick survival than others, identifying and ameliorating factors that contribute to low fledging success will likely boost productivity at these sites.

Local and cross-seasonal associations of climate and land use with abundance of monarch butterflies Danaus plexippus

Quantifying how climate and land use factors drive population dynamics at regional scales is complex because it depends on the extent of spatial and temporal synchrony among local populations, and the integration of population processes throughout a species’ annual cycle. We modeled weekly, site-specific summer abundance (1994–2013) of monarch butterflies Danaus plexippus at sites across Illinois, USA to assess relative associations of monarch abundance with climate and land use variables during the winter, spring, and summer stages of their annual cycle. We developed negative binomial regression models to estimate monarch abundance during recruitment in Illinois as a function of local climate, site-specific crop cover, and county-level herbicide (glyphosate) application. We also incorporated cross-seasonal covariates, including annual abundance of wintering monarchs in Mexico and climate conditions during spring migration and breeding in Texas, USA. We provide the first empirical evidence of a negative association between county-level glyphosate application and local abundance of adult monarchs, particularly in areas of concentrated agriculture. However, this association was only evident during the initial years of the adoption of herbicide-resistant crops (1994–2003). We also found that wetter and, to a lesser degree, cooler springs in Texas were associated with higher summer abundances in Illinois, as were relatively cool local summer temperatures in Illinois. Site-specific abundance of monarchs averaged approximately one fewer per site from 2004–2013 than during the previous decade, suggesting a recent decline in local abundance of monarch butterflies on their summer breeding grounds in Illinois. Our results demonstrate that seasonal climate and land use are associated with trends in adult monarch abundance, and our approach highlights the value of considering fine-resolution temporal fluctuations in population-level responses to environmental conditions when inferring the dynamics of migratory species.

Factors influencing nest survival and renesting by Piping Plovers in the Great Lakes region

ABSTRACT Renesting is an important breeding strategy used by birds to compensate for nest failure. If birds renest, clutch removal for captive rearing can be used to augment endangered populations; however, not all individuals renest following nest loss, and later nesting attempts may have lower survival rates and clutch sizes. We investigated variation in nest initiation date, clutch size, daily nest survival, renesting propensity, and renesting intervals of federally endangered Great Lakes Piping Plovers (Charadrius melodus) from 1993 to 2010. We also compared productivity under hypothetical clutch removal for captive rearing vs. non-removal scenarios. Nest initiation date was earlier for older adults and was more strongly affected by female than male age. Clutch size and nest survival decreased with later nest initiation, and nest survival increased with male age and nest age until close to hatching. Overall, Piping Plovers replaced 49% of failed nests. Renesting propensity decreased with later date, increased with each successive nesting attempt, and varied according to cause of failure; probability of renesting was highest following flooding and lowest for inviable clutches. Renesting intervals increased with age of the previous nest and averaged 4.2 days longer for birds that changed mates. Results also indicated that, compared to leaving eggs in situ, clutch removal for captive rearing would produce 43% fewer 1-year-old recruits, partly because renesting does not fully offset clutch removal; therefore, efforts to increase fledging success in this endangered population should focus on proactively protecting nests in situ rather than relying on collection of eggs for captive rearing.

Factors influencing breeding success, ovarian cyclicity, and cub survival in zoo-managed tigers (Panthera tigris)

Understanding factors that influence reproduction and offspring survival in zoo populations is critical for management of threatened and endangered species. Examination of long-term data (1989-2011) compiled from the Association of Zoos and Aquariums zoo-managed tiger breeding program provides the basis for a more thorough understanding of reproduction and scientifically based decisions for effective population management in this endangered felid. Biological and management-related factors that could influence tiger breeding success and cub survival were evaluated using logistic mixed models. Breeding success improved with female age until approximately age five, then declined thereafter. Experienced female breeders had greater breeding success than inexperienced females. Litter size was most predictive of cub survival, with average-sized litters (3-4 cubs) experiencing the highest proportional survival. Management-related factors, such as whether the breeding institution had a recent tiger litter and whether both animals were already located at the same institution, also influenced breeding success and cub survival. These results highlight the importance of institutional husbandry experience and the need to retain knowledge through staff turnovers to achieve optimal reproductive success. Using fecal estrogen data, frequency of ovarian cyclicity and mean cycle length did not differ by female age or parity; thus, lack of cyclicity and/or increased cycle duration are not likely explanations for declining breeding success with age. These results provide valuable reproductive information that should improve scientific management of zoo-based tiger populations.

Outbreak of Campylobacteriosis Associated with Raccoon Contact at a Wildlife Rehabilitation Centre, Minnesota, 2013.

Campylobacteriosis is an enteric illness caused by bacteria of the genus Campylobacter. There are approximately 900 culture‐confirmed cases of campylobacteriosis reported annually to the Minnesota Department of Health (MDH). Case patients are interviewed about risk factors, including foods eaten, recreational and drinking water exposures and animal contact. In September 2013, MDH identified two Campylobacter jejuni cases who reported working at the same wildlife rehabilitation centre before illness onset. This report describes the investigation, which used a case–control study design, and identified 16 additional ill persons, for a total of 18 ill persons. Both cases and controls reported working with a variety of animals, including squirrels, chipmunks, mice, raccoons, opossums, rabbits, songbirds, waterfowl and reptiles. In univariate analyses, contact with a number of different animal species was significantly associated with illness, including raccoons (odds ratio [OR], 11.1; P < 0.001), chipmunks (OR, 3.65; P = 0.01), opossums (OR, 4.38; P = 0.005), mice (OR, 4.18; P = 0.01) and rabbits (OR, 4.36; P = 0.003). In a multivariate model, contact with raccoons was the only exposure independently associated with illness (adjusted OR, 12.2; P = 0.01). Bacterial culture and subtyping of the outbreak strain of C. jejuni from raccoon faecal samples further implicated raccoons as the source of the outbreak. Not all of the cases reported handling raccoons, suggesting that environmental contamination contributed to transmission. MDH worked with the wildlife rehabilitation centres management to strengthen biosecurity and infection control protocols.