Quasi-extinction risk and population targets for the Eastern, migratory population of monarch butterflies (Danaus plexippus)

The Eastern, migratory population of monarch butterflies (Danaus plexippus), an iconic North American insect, has declined by ~80% over the last decade. The monarch’s multi-generational migration between overwintering grounds in central Mexico and the summer breeding grounds in the northern U.S. and southern Canada is celebrated in all three countries and creates shared management responsibilities across North America. Here we present a novel Bayesian multivariate auto-regressive state-space model to assess quasi-extinction risk and aid in the establishment of a target population size for monarch conservation planning. We find that, given a range of plausible quasi-extinction thresholds, the population has a substantial probability of quasi-extinction, from 11–57% over 20 years, although uncertainty in these estimates is large. Exceptionally high population stochasticity, declining numbers, and a small current population size act in concert to drive this risk. An approximately 5-fold increase of the monarch population size (relative to the winter of 2014–15) is necessary to halve the current risk of quasi-extinction across all thresholds considered. Conserving the monarch migration thus requires active management to reverse population declines, and the establishment of an ambitious target population size goal to buffer against future environmentally driven variability

Habitat Fragmentation and Movements of Three Small Mammals (Sigmodon, Microtus, and Peromyscus)

We studied the effects of habitat fragmentation on the movements of cotton rats (Sigmodon hispidus), deer mice (Peromyscus maniculatus), and prairie voles (Microtus ochrogaster) living in a fragmented landscape using 7.7 yr (1984—1992) of mark—recapture data. The study area included three kinds of 0.5—ha blocks: single large patches (5000 m2), clusters of medium patches (27 88 m2), and clusters of small patches (32 m2). We tested three predictions regarding animal movements. First, animals should move longer distances as fragmentation increases. Second, the proportion of animals moving will decrease as fragmentation increases. Third, species will show more movement from putative sources to putative sinks. In support of our first two predictions, all species (except male cotton rats) moved farther, and lower proportions of animals moved, as fragmentation increased. In testing our third prediction, we found no trends, for all species, between patch size and the net number of animals a block either imported or exported, indicating source—sink dynamics were probably not occurring on our study site. Furthermore, animals of all species (except female deer mice) switched more frequently to blocks of larger patches. For prairie voles in the spring and deer mice in the summer, relative abundances among blocks predicted from a Markov matrix model of switching probabilities showed high congruence with the actual abundances, indicating movement and abundances were related. In both cotton rats and prairie voles but not in deer mice, more juveniles and nonreproductive animals switched between blocks than did adults or reproductive animals. Deer mice switched more frequently than did either cotton rats or prairie voles; the latter species switched in similar frequencies. We discuss the implications of our data for modeling and conservation

Historical land use and land cover for assessing the northern Colorado Front Range urban landscape

We describe historical land-use and land-cover (LULC) maps for the northern Colorado urban Front Range. The Front Range urban landscape is diverse and interspersed with highly productive agriculture, as well as natural land cover types including evergreen forest in the Rocky Mountain foothills and Great Plains grassland. To understand the dynamics of urban growth, raster maps were created at a 1-meter resolution for each of four time steps, nominally 1937, 1957, 1977, and 1997. In total, 38 detailed LULC classes were identified using manual interpretation techniques, aerial photographs, historical maps, and other available information. The maps provide high-resolution spatial data for understanding the historical progression of urbanization and will allow further analysis of the effects of urban growth on social and ecological systems

Biology _______________

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Appendix D. A table showing hierarchical multiple linear regression models examining factors influencing native woody species richness in two sample years.

A table showing hierarchical multiple linear regression models examining factors influencing native woody species richness in two sample years

The interaction of habitat fragmentation, plant and small mammal succession in an old field

We compared the density and spatial distribution of four small mammal species (Microtus ochrogaster, Peromyscus maniculatus, Sigmodon hispidus, and P. leucopus) along with general measures of an old field plant community across two successional phases (1984–1986 and 1994–1996) of an experimental study of fragmentation in eastern Kansas. During the early phase the plant community was characterized by little spatial or temporal variance across patch size, consistent with spatially neutral models of succession. In contrast, there was a strong, species-specific effect of patch size on small mammal species distribution and abundance. The lack of variance in vegetation structure across patch size during the early seres suggests that small mammal distributions were responding in large part to features of the system other than variance in vegetation structure and composition across patch size. As succession proceeded, the colonization of the system by woody plant species precipitated a series of patch size effects on plant community composition. Differential habitat selection by small mammals at the patch scale tracked these changes in plant distribution. For example, M. ochrogaster and S. hispidus shifted their distributions away from less fragmented patches toward smaller patches, where retarded plant succession had maintained an earlier sere. P. leucopus successfully colonized and maintained high densities only on large patches, where plant succession had progressed most rapidly toward a woody-species-dominated community. Our results highlight the role of landscape structure in long-term community dynamics and indicate that some of the complexity observed in successional systems may result from the structure and composition of the landscape mosaic. In general, our results suggest that to fully understand long-term change within communities, the influence of landscape structure on patterns of heterogeneity in both vegetation and consumer dynamics must be understood. Moreover, the long-term and landscape-scale perspectives afforded by our study provide insight into community dynamics that might otherwise be missed

Effects of Tree Island Size and Water on the Population Dynamics of Small Mammals in the Everglades

Tree islands in the Everglades prairie provided a unique opportunity to study how patch dynamics affect population processes in two small mammal species, the marsh rice rat and hispid cotton rat. We assessed the effect of island size and water on density, survivorship, reproduction, and movement in both these species. Rice rats had the highest densities on the small islands, while survivorship and reproductive activity was not affected by island size. Cotton rats had the highest densities and reproductive activity on large islands, while survivorship and reproduction was not affected by island size In both species, the highest proportion of animals moved from small islands

Appendix E. A table showing hierarchical multiple linear regression models examining factors influencing density of live adult native woody species in two sample years.

A table showing hierarchical multiple linear regression models examining factors influencing density of live adult native woody species in two sample years