2 results
Chapter 10 - Population Regulation
- Dries Van Nieuwenhuyse, EHSAL Management School, Brussels, Belgium, Ronald van Harxen, Dutch Little Owl Working Group (STONE), David H. Johnson, Global Owl Project, USA
- Illustrated by Joris De Raedt
-
- Book:
- The Little Owl
- Published online:
- 29 September 2023
- Print publication:
- 19 October 2023, pp 405-479
-
- Chapter
- Export citation
-
Summary
Little Owls have been shown to be directly and indirectly affected by habitat loss, vehicle collisions, limited availability of nest and roosting sites, pesticides (i.e., secondary poisoning) and heavy metals, entrapment in anthropogenic structures (i.e., hollow metal power poles and chimneys, and drowning in water troughs), predators and weather. They are susceptible to parasites, diseases and injuries too. While the Little Owl has co-evolved with a few of these (e.g., weather, predators, diseases, parasites), anthropogenic activities have substantially altered the landscape within which Little Owls exist(ed). When the population grows and owl densities become higher, density-dependent processes take place and serve to stabilise the population. In a metapopulation context, as populations become increasingly small, immigration helps to support them, extending the survival time of these population clusters. The mating system hypothesis, which predicts that the sex that establishes the territory should disperse shorter distances, was studied using the EURING data set containing 108 444 observations of ringing, re-capture and recovery data for 59 743 unique ringed birds. Little Owls ringed as young and recovered at least one year later dispersed on average 14.69 km for females, 6.47 km for males and 11.61 km for birds with unknown sex for live re-captures. Birds ringed as adults and then later recovered dispersed 2.33 km for females, 2.45 km for males and 2.42 km for birds with unknown sex for live re-captures.
Raptor migration at Guantouling, south-west China: phenology, weather influence and persecution pressure
- XU SHI, XIAOBO XIAO, XINYI ZHAO, RENJIE SUN, XINGFENG ZHAO, CHI-YEUNG CHOI, WUYING LIN
-
- Journal:
- Bird Conservation International / Volume 33 / 2023
- Published online by Cambridge University Press:
- 11 November 2021, e2
-
- Article
- Export citation
-
South-west China, particularly between the Himalayas and the Beibu Gulf, constitutes an important corridor for migratory raptors along the East-Asian continental flyway. However, a lack of ornithological assessment and the common practice of illegal hunting in this region emphasize the need for research and conservation actions. To investigate the ecology of migration and scale of persecution, we launched one of the first citizen-science projects in mainland China to record southward-migrating raptors and hunting gunshots from 2015 to 2019 on Guantouling, a well-known raptor site in South-west China. A total of 42,891 raptors were recorded, belonging to 30 diurnal raptor species. Grey-faced Buzzard Butastur indicus, Oriental Honey Buzzard Pernis ptilorhynchus and Amur Falcon Falco amurensis were the three most abundant species recorded. The bulk of Grey-faced Buzzard and Amur Falcon migrated through Guantouling from mid-October till early November, while Oriental Honey Buzzard migrated throughout October and early November. Precipitation slowed down migration significantly while increasing cloud cover was favoured by the three most abundant species. We found hunting mostly occurred in the afternoon, coinciding with an increasing number of Oriental Honey Buzzard, which may become a major victim of hunting. It is thus suggested to prioritize peak raptor migration period for law enforcement actions, especially on cloudy days and after passage of cold fronts, when Oriental Honey Buzzards and other species are likely to migrate. The annual counting scheme on Guantouling is not only an ecological survey, but also an effective way of engaging the public to counter raptor persecution.
![](/core/cambridge-core/public/images/lazy-loader.gif)