Bird tolerance to humans in open tropical ecosystems

AbstractAnimal tolerance towards humans can be a key factor facilitating wildlife–human coexistence, yet traits predicting its direction and magnitude across tropical animals are poorly known. Using 10,249 observations for 842 bird species inhabiting open tropical ecosystems in Africa, South America, and Australia, we find that avian tolerance towards humans was lower (i.e., escape distance was longer) in rural rather than urban populations and in populations exposed to lower human disturbance (measured as human footprint index). In addition, larger species and species with larger clutches and enhanced flight ability are less tolerant to human approaches and escape distances increase when birds were approached during the wet season compared to the dry season and from longer starting distances. Identification of key factors affecting animal tolerance towards humans across large spatial and taxonomic scales may help us to better understand and predict the patterns of species distributions in the Anthropocene.</jats:p

Spatial behaviour and food choice of the Garden Warbler Sylvia borin during the non-breeding season

Information regarding the spatial behaviour of migratory bird species on their  wintering ground is important in understanding the factors that can influence  breeding success and population size. The Garden Warbler Sylvia borin is a migratory species that has been well studied in West Africa. However, information regarding its spatial behaviour during the non-breeding season in sub-Saharan Africa is still limited. Consequently, we investigated the 50% and 95% kernel density home-range size and overlap as well as food choice of 10 radio-tracked Garden Warblers at Amurum, central Nigeria and Obudu, south-eastern Nigeria. Home-range overlap was estimated using the kernelUD function within the package adehabitat in R. The mean home-range was 7.0 ha and 3.3 ha at Amurum and Obudu, respectively, whereas the core of the home-range was on average 1.5 ha and 0.7 ha, respectively. Mean home-ranges were larger than the average territory of individuals on the temperate breeding grounds. Home-range overlap ranged between 19% and 57% at Amurum and 39% and 71% at Obudu, suggesting that Garden Warblers are not territorial during the non-breeding season in Nigeria. The diet of the Garden Warblers at both sites comprised of berries and insects and several  individuals were often observed foraging together.Comportement spatial et choix alimentaires chez la Fauvette des jardins Sylvia borin en dehors de la saison reproductive Les informations concernant le  comportement spatial des espèces d’oiseaux migrateurs sur leur territoire hivernalsont importantes pour comprendre les facteurs pouvant influencer le succès  reproducteur et la taille des populations. La Fauvette des jardins Sylvia borin est une espèce migratoire largement étudiée en Afrique de l’ouest. Cependant, les informations concernant le comportement spatial de cette espèce en dehors de sa période de reproduction sont limitées en Afrique subsaharienne. Par conséquent, nous nous sommes intéressés au estimations de densités par le noyau à 50 % et 95 % de la taille et du chevauchement du domaine vital, ainsi qu’aux choix alimentaires de dix Fauvettes des jardins radio monitorées dans le centre et le sud-est du Nigeria, à Amurum et Obudu respectivement. Le chevauchement de l’aire vitale a été déterminé avec la fonction kernelUD du package adehabitat du logiciel R. L’aire vitale moyenne est de 7,0 ha à Amurum et de 3,3 ha à Obudu, tandis que le coeur de l’aire vitale est en moyenne de 1,5 ha et 0,7 ha respectivement. Les  domaines vitaux moyens étaient supérieurs à la taille moyenne du territoire des individus sur les zones de reproduction tempérées. Le chevauchement des aires vitales va de 19 % à 57 % à Amurum et de 39 % à 71 % à Obudu, suggérant qu’au Nigeria les Fauvettes des jardins ne sont pas territoriales en dehors de leur saison de reproduction. Sur les deux sites le régime des Fauvettes des jardins comprenait des baies et des insectes et il était fréquent d’observer de nombreux individus fourrageant ensemble.Keywords: diet, Garden Warbler, home-range, home range overlap, kernel density, spatial behaviour, utilisation distributio

Autumn phenology and morphometrics in the Garden Warbler Sylvia borin at the Ottenby Bird Observatory, Sweden

Trapping and ringing near ecological barriers can provide useful information about the migration strategies of bird species. In this paper we analyzed ringing data of the Garden Warbler, collected within the period of 1950-2008 at the Ottenby Bird Observatory, south-eastern Sweden, and describe patterns in migration phenology, morphometrics and fuel load. A total of 4,351 individuals aged as either adults or juveniles were ringed during the period (yearly averages 7.3 adults and 83.1 juveniles) in addition to 1,514 birds of unknown age. Both age-specific and combined yearly totals did not significantly vary over the years. Median passage dates were 24 August, 30 August and 2 September for adults, juveniles and birds of unknown age, respectively. Median passage did not change significantly over the years. Among adults, larger individuals passed the observatory earlier than smaller individuals. The average fuel load was estimated at 24.3% of Lean Body Mass (LBM), and late-migrating individuals had higher fuel deposits than early migrants. Maximum fuel load was estimated at 82.5% of LBM; such an individual may be capable of a direct flight from Ottenby region to the Mediterranean area

Intra-African movements of the African cuckoo Cuculus gularis as revealed by satellite telemetry

Despite many bird species migrating regularly within the African continent, in response to rainfall and breeding opportunities, documented evidence of the spatiotemporal patterns of such movements is scarce. We use satellite telemetry to document the year round movement of an intra-African migrant breeding in the savannah zone of sub-Saharan Africa, the African cuckoo. After breeding in central Nigeria, the birds migrated to more forested sites in the Adamawa region of Cameroon (n = 2) and western Central African Republic (n = 1). Departure from the breeding ground coincided with deteriorating environmental conditions whereas arrival at the non-breeding sites matched period of increasing vegetation greenness. Migratory movements generally occurred during dark hours. In total, an average distance of 748 km in 66 d was covered during the post-breeding migration and 744 km in 27 d during return journey with considerable individual variation and with more stopover sites used during post-breeding migration. The diversity of migration routes followed suggests a relatively variable or flexible initial migration strategy, high individual route consistency as well as high fidelity for non-breeding grounds

Population trends of resident and migrant West African bird species monitored over an 18-year period in central Nigeria

Almost no systematic monitoring of bird population trends occurs in West Africa, despite rapid human population increase, habitat change, and climate change, making conservation planning problematic. We monitored bird population trends using constant-effort mist netting, in a newly protected area (Amurum Forest Reserve) on the outskirts of Jos, central Nigeria, from 2002 to 2019. We modelled the 18-year changes in trends of 10 Palearctic migrant and 41 common resident bird species and related this to any changes in annual environmental site quality using NDVI and rainfall data. The populations of most bird species were stable; 30% of migrants and 7% of residents increased, while 10% of migrants and 29% of residents declined moderately. Primary productivity, measured by NDVI, increased, and rainfall pattern was stable, suggesting that environmental conditions at the site improved slightly during the period. However, only a few species showed significant correlations of population trends with NDVI and rainfall. Overall, our results suggest that population changes were locally similar for both the Afro-Palearctic and resident bird species, being reasonably stable or increasing — although perhaps this reflected the fact that the monitoring was done within a newly protected area, which at present represents the best habitat in the wider locality. Those species that declined were mostly associated with open, grassland areas, which will have decreased as anthropogenic influences were reduced at the study site. Though we only monitored one site, the results are encouraging in that simple protection of a small habitat fragment (~300 ha) in Nigeria yielded generally positive population benefits for both resident and Palearctic migrant species

Population trends of resident and migrant West African bird species monitored over an 18-year period in central Nigeria

This is paper no. 208 from the A.P. Leventis Ornithological Research Institute (APLORI).Almost no systematic monitoring of bird population trends occurs in West Africa, despite rapid human population increase, habitat change, and climate change, making conservation planning problematic. We monitored bird population trends using constant-effort mist netting, in a newly protected area (Amurum Forest Reserve) on the outskirts of Jos, central Nigeria, from 2002 to 2019. We modelled the 18-year changes in trends of 10 Palearctic migrant and 41 common resident bird species and related this to any changes in annual environmental site quality using NDVI and rainfall data. The populations of most bird species were stable; 30% of migrants and 7% of residents increased, while 10% of migrants and 29% of residents declined moderately. Primary productivity, measured by NDVI, increased, and rainfall pattern was stable, suggesting that environmental conditions at the site improved slightly during the period. However, only a few species showed significant correlations of population trends with NDVI and rainfall. Overall, our results suggest that population changes were locally similar for both the Afro-Palearctic and resident bird species, being reasonably stable or increasing—although perhaps this reflected the fact that the monitoring was done within a newly protected area, which at present represents the best habitat in the wider locality. Those species that declined were mostly associated with open, grassland areas, which will have decreased as anthropogenic influences were reduced at the study site. Though we only monitored one site, the results are encouraging in that simple protection of a small habitat fragment (∼300 ha) in Nigeria yielded generally positive population benefits for both resident and Palearctic migrant species.Publisher PDFPeer reviewe

Population trends of resident and migrant West African bird species monitored over an 18-year period in central Nigeria

Almost no systematic monitoring of bird population trends occurs in West Africa, despite rapid human population increase, habitat change, and climate change, making conservation planning problematic. We monitored bird population trends using constant-effort mist netting, in a newly protected area (Amurum Forest Reserve) on the outskirts of Jos, central Nigeria, from 2002 to 2019. We modelled the 18-year changes in trends of 10 Palearctic migrant and 41 common resident bird species and related this to any changes in annual environmental site quality using NDVI and rainfall data. The populations of most bird species were stable; 30% of migrants and 7% of residents increased, while 10% of migrants and 29% of residents declined moderately. Primary productivity, measured by NDVI, increased, and rainfall pattern was stable, suggesting that environmental conditions at the site improved slightly during the period. However, only a few species showed significant correlations of population trends with NDVI and rainfall. Overall, our results suggest that population changes were locally similar for both the Afro-Palearctic and resident bird species, being reasonably stable or increasing—although perhaps this reflected the fact that the monitoring was done within a newly protected area, which at present represents the best habitat in the wider locality. Those species that declined were mostly associated with open, grassland areas, which will have decreased as anthropogenic influences were reduced at the study site. Though we only monitored one site, the results are encouraging in that simple protection of a small habitat fragment (∼300 ha) in Nigeria yielded generally positive population benefits for both resident and Palearctic migrant species