Occupancy

About: Occupancy is a research topic. Over the lifetime, 2757 publications have been published within this topic receiving 68288 citations.

A four‐year investigation into the efficacy of domiciles for enhancement of bumble bee populations

Abstract: 1 Eighty four-unit domiciles for introduced bumble bees (Bombus spp) were placed in 16 field margins at Lincoln, New Zealand in the 1995–96 southern summer Fifty-five were placed in the margins of intensively managed fields, with the remaining 25 being in less disturbed habitats, which had more spring/summer floral resources 2 The number of nests founded over the four-year study period increased from one to 27 Bombus hortorum was a much more frequent colonist than was B terrestris, with B ruderatus colonizing only in the fourth year 3 In the ‘intensive’ sites, mean four-year occupancy was only 2%, whereas in the less disturbed sites it was 13% 4 There was a positive association between bumble bee occupancy of the domicile compartments in the previous year and occupancy in the current year No association was found between previous occupancy by mice and subsequent occupancy by bumble bees 5 The potential for adding Bombus nest sites to agricultural land to enhance local populations, and, potentially, pollination of seed crops, is discussed Adding domiciles in intensively managed landscapes may not be very effective unless spring floral resources are enhanced as well

Occupancy reliably reflects territory quality in a long‐lived migratory bird, the white stork

Abstract: Patterns of territory occupancy were studied in the population of ca. 200 pairs of white stork Ciconia ciconia breeding in central Poland from 1994 to 2011. We tested whether occupation rate in this species correlated with different indices of territory quality and reproductive performance of nesting birds. Territory occupancy deviated significantly from random pattern, as nearly half of the territories were occupied for over 75% of all breeding seasons. It was found that white storks returning to breeding grounds in spring settled earlier in the territories of higher occupancy. There was a positive association between territory occupancy and productivity of storks, which could be explained by the lower prevalence of brood reduction in the longer occupied territories. Finally, we demonstrated that occupancy positively correlated with the share of high-quality habitats (wetlands) in the foraging territories of storks. All these relationships indicate that territory occupancy may be used to reliably assess attractiveness of particular nesting territories and to identify key areas for white storks. We also suggest that the application of this simple measure of territory quality could well enhance conservation efforts directed at long-lived migratory birds.

Mapping large-scale bird distributions using occupancy models and citizen data with spatially biased sampling effort

Abstract: Aim Although data collected by citizen scientists have received a great deal of attention for assessing species distributions over large extents, their sampling efforts are usually spatially biased. We assessed whether the bias of spatially varied sampling effort for opportunistic citizen data can be corrected using occupancy models that incorporate observation processes. Location Hokkaido Island, northern Japan. Methods We applied occupancy models for citizen data with spatially biased sampling effort to model and map large-scale distributions of 52 forest and 23 grassland/wetland bird species. We used estimated species richness (summed occupancy probabilities among the species) as the aggregated distributional patterns of each species group and compared them among two occupancy models (i.e. single-species and multispecies occupancy models), two conventional logistic regression models and Maxlike, which do not explicitly deal with observation processes. Results Conventional logistic regression models and Maxlike predicted inappropriate patterns, such as forest species preferring lowland non-forested areas where most of the data were collected. Occupancy models, however, showed more appropriate results, indicating that forest species preferred lowland forested areas. The prediction by logistic models was somewhat improved by the use of spatially biased non-detection data as the absence data; however, estimates of species richness were still much lower than those of occupancy models. Differences in model outputs were evident for the forest species but not for grassland/wetland species because citizen data covered virtually all environmental niches for grassland/wetland species. Results of the single-species and multispecies occupancy models were nearly identical, but in some cases, estimates from the single-species models were not converged or deviated notably from those of other species compared with estimates by the multispecies model. Main conclusions We found that citizen data with spatially biased sampling effort can be appropriately utilized for large-scale biodiversity distribution modelling with the use of occupancy models, which encourages data collection by citizen scientists.

Long‐term effects of global change on occupancy and flight period of wild bees in Belgium

Abstract: Global change affects species by modifying their abundance, spatial distribution and activity period. The challenge is now to identify the respective drivers of those responses and to understand how those responses combine to affect species assemblages and ecosystem functioning. Here, we correlate changes in occupancy and mean flight date of 205 wild bee species in Belgium with temporal changes in temperature trend and interannual variation, agricultural intensification and urbanization. Over the last 70 years, bee occupancy decreased on average by 33%, most likely because of agricultural intensification, and flight period of bees advanced on average by 4 days, most likely because of interannual temperature changes. Those responses resulted in a synergistic effect because species which increased in occupancy tend to be those that have shifted their phenologies earlier in the season. This leads to an overall advancement and shortening of the pollination season by 9 days and 15 days respectively, with lower species richness and abundance compared to historical pollinator assemblages, except at the early start of the season. Our results thus suggest a strong decline in pollination function and services.