Yellow-billed Magpie Population Status and Habitat Characteristics in Urban Sacramento, California

Most research on the ecology of the Yellow-billed Magpie (Pica nuttalli) has been focused in oak woodlands and savannas in California’s Coast Ranges; urban and suburban populations, some of which are sizable, have received little attention. In 2020, we studied eight colonies in six parks around Sacramento and in 2021 expanded the survey to 43 sites, detecting 827 breeding magpies. Population estimates based on nest counts were generally higher than those from direct counts, and nest counts were more repeatable and efficient. Counts of recently fledged young in family groups yielded reproductive rates similar to those observed near the coast before arrival of West Nile virus in 2003, suggesting that the virus is not currently affecting nestlings’ survival. Sacramento magpies nested in the upper canopy of a wide variety of large trees, both native and non-native. They foraged preferentially in low herbaceous habitat—irrigated turf and unirrigated annual grassland that was mowed or grazed. The presence of rivers and streams influenced occupancy strongly. Colony size was strongly related to the amount of low herbaceous foraging habitat within 0.5 km of colony sites with nearby flowing water. Our results suggest that at least 4 ha of low herbaceous foraging habitat is needed to support a small nesting colony. Retention of herbaceous habitat near large trees and flowing water, plus mowing or grazing to keep herbaceous growth low, should benefit urban Yellow-billed Magpies.

Abundance and diurnal activity patterns of hooded vulture (Necrosyrtes monachus Temminck,) in Addis Ababa abattoirs enterprise, Addis Ababa, Ethiopia

Hooded vulture (Necrosyrtes monachus) is an African endemic scavenger listed as Critically Endangered species. The population is declining across its range and there is threat of significant decline in population and distribution in Ethiopia. Little efforts have been made to properly document the status of vulture population and their diurnal activity patterns in the country for ensuring long term conservation measures. A study was conducted in Addis Ababa Abattoirs enterprise, Ethiopia from November 2019 to January 2020 to investigate the abundance and diurnal activity patterns of hooded vultures. The abundance of these vultures was estimated by direct counts method at their feeding sites and scan sampling was employed to study the diurnal activity patterns of hooded vultures from dawn to dusk. Hooded vulture mean abundance was 216±40 at the abattoir. Their diurnal activity pattern showed that they were observed feeding, resting (perching, watching and basking), preening, roosting and others activities such as walking, drinking, chasing and flying. They spent 37.73% of their time in resting followed by others (including walking, drinking, chasing and flying) (27.73%). The major threat recorded for theses vultures in the abattoir includes shortage of food, human disturbances, negative attitudes and lack of awareness on the importance of the species. Further ecological studies and impacts of human activities on Addis Ababa Abattoirs enterprise should be conducted for the conservation of hooded vulture and other conspecifics in the area.

How reliable is the use of transect counts to assess the population of the New Forest Burnet moth (Zygaena vicae [D. & S.], 1775) (Lepidoptera: Zygaenidae) at its only British site in western Scotland

The population of the New Forest burnet moth, Zygaena viciae, at its only UK site in western Scotland, was assessed between 1990 and 2019, using direct counts, standard transect counts and Mark/Release/Recapture (MRR). Data from eleven of these years, when reliable comparative transect counts and MRR population estimates were available, were analysed to answer the question as to whether the more economical transect counts provided a reliable estimate of the population size. Lin's Concordance Coefficient showed conclusively that transect counts do have a consistent relationship with the MRR population estimates. However, it was found that transect counts consistently under-estimate the MRR derived population estimates and that the scaling factor between them is best valued at ×5 (see Results). It can be concluded that, when resources are too limited to allow a full MRR population analysis, the more economical transect counts can trusted to indicate the relative size of the moth population.

Giant otter Pteronura brasiliensis density and abundance in Llanos Orientales de Colombia in the Orinoco basin

The giant otter Pteronura brasiliensis, categorized as Endangered on the IUCN Red List, was once widely distributed throughout South America. By the middle of the 20th century the giant otter had become locally extinct along the main rivers of the Orinoco basin. Although some populations seem to have recovered, the paucity of information available does not permit a full evaluation of the species' conservation status. The objective of this study was to estimate the abundance and density of the giant otter population along the Orinoco river in the municipality of Puerto Carreño, Vichada, Colombia, where there is important commercial and recreational fishing. Thirty-nine linear km were surveyed, repeatedly, with a total of 315 km of surveys. Population size was estimated by direct counts of individuals. All individuals detected were photographed and identified individually from their throat pelage patterns. In total, 30 otters were identified, giving a minimum density of 0.77 individuals per km, one of the highest reported for the species in Colombia. Given the high density in this well-developed area, our results highlight the importance of this population for the conservation of the species.

Comparison of methods for quantifying primordial follicles in the mouse ovary

Background Accurate evaluation of primordial follicle numbers in mouse ovaries is an essential endpoint for studies investigating how endogenous and exogenous insults, such as maternal aging and chemotherapy, impact the ovarian reserve. In this study, we compared and contrasted two methods for counting healthy primordial follicles following exposure to cyclophosphamide (75 mg/kg), a well-established model of follicle depletion. The first was the fractionator/optical dissector technique, an unbiased, assumption-free stereological approach for quantification of primordial follicle numbers. While accurate, highly reproducible and sensitive, this method relies on specialist microscopy equipment and software, requires specific fixation, embedding and sectioning parameters to be followed, and is largely a manual process that is tedious and time-consuming. The second method was the more widely used serial section and direct count approach, which is relatively quick and easy. We also compared the impacts of different fixatives, embedding material and section thickness on the overall results for each method. Results Direct counts resulted in primordial follicle numbers that were significantly lower than those obtained by stereology, irrespective of fixation and embedding material. When applied to formalin fixed tissue, the direct count method did not detect differences in follicle numbers between saline and cyclophosphamide treated groups to the same degree of sensitivity as the gold standard stereology method (referred to as the Reference standard). However, when Bouin’s fixative was used, direct counts and stereology were comparable in their ability to detect follicle depletion caused by cyclophosphamide. Conclusions This work indicates that the direct count method can produce similar results to stereology when Bouin’s fixative is used instead of formalin. The findings presented here will assist others to select the most appropriate experimental approach for accurate follicle enumeration, depending on whether the primary objective of the study is to determine absolute primordial follicle numbers or relative differences between groups.

Population density of eastern grey kangaroos (Macropus giganteus) in a periurban matrix at Coffs Harbour, New South Wales

We surveyed eastern grey kangaroos at four locations at the Northern Beaches region of Coffs Harbour, New South Wales, to estimate densities in this growing peri-urban region. This region is considered a regional hotspot for human–kangaroo conflict, with numerous kangaroo-related incidents in recent years. Direct counts of kangaroos were undertaken every two months during 2016. Kangaroo densities varied between sites, ranging from 0.2 individuals ha–1 to 4.9 individuals ha–1. Because no estimates of population density exist for the Northern Beaches, our results assisted the development of a regional kangaroo management plan, and contribute to a broader understanding of eastern grey kangaroo densities in peri-urban areas.

Estimates of Minimum Population Size for Walrus near Southeast Baffin Island, Nunavut

To support management objectives in Canada and Greenland, joint research between the Department of Fisheries and Oceans and Greenland Institute of Natural Resources was begun in 2005. Direct counts were used to determine the Minimum Counted Population (MCP) in summer around SE Baffin Island. Aerial surveys examined the coast from roughly the Saddleback Island in northern Hudson Strait to Isabella Bay on eastern Baffin Island but concentrated on the area between Loks Land and Cape Dyer. The maximum count was obtained on 3–4 September 2007 during boat surveys. The MCP ranged from 716 (in 2006) to 1,056 (2007). Using the largest MCP adjusted with published maximum estimates of the proportion of walrus hauled out concurrently, we estimated 1,420 (95% CI: 1,219–1,622) walrus were present. In addition, four walrus had been fitted with satellite relayed data logger tags prior to the maximum counts in 2007. Using the simple proportion of ‘tags dry’ on 3 September to adjust counts on 3 and 4 September 2007 provided an estimate of 2,102 (CI = MCP-4,482). Using the proportion of time dry immediately preceding the survey to adjust the maximum count produced an estimate of 2,502 (CI = 1,660–3,345) walrus were present in Hoare Bay. We conclude approximately 2,100–2,500 walrus were present in Hoare Bay in late summer 2007. This number is a negatively biased estimator of the population of walrus around SE Baffin Island and in the Hudson Bay–Davis Strait stock as a whole. Broader survey coverage in a short period and more detailed information on the movement of walrus between Greenland and Canada and the summer dispersal of these animals within Canada are required to improve population estimates.