Valentijn S. van Bergen

Valentijn S. van Bergen
Swiss Ornithological Institute

Bachelor of Applied Science

About

12
Publications
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Citations
Introduction
Valentijn van Bergen currently works at The Schweizerische vogelwarte as a research assistant in a project on red kites Milvus milvus. Life-long experience in raptor studies, with an obsession for Honey-buzzards.

Publications

Publications (12)
Article
Full-text available
The activities surrounding, and use of, four summer nests of Honey Buzzards (nests built in summer but without egg-laying, called ‘Spielnest’ in the past by German authors) and a Buzzard nest refurbished by Honey Buzzard were continuously tracked by means of Reconyx HC 600 cameras. The cameras were either used with time-lapse (each minute one photo...
Article
Full-text available
Whilst monitoring parental investment of a Buzzard Buteo buteo pair in the northern Netherlands in 2015 by means of a trap camera (taking a photograph each minute), the birds were found to continue incubation well after the expected hatching date. The first egg was laid around 6 April. Up to and including 9 May, the expected hatching day, the femal...
Research
Full-text available
In 2018 a nest of Honey-buzzard Pernis apivorus was found during a research project on Red kites Milvus milvus in Switzerland in an area where the cantons of Bern and Fribourg border. The diet was analysed by using a camera trap at the nest. In 2019 I started a private project to get an insight in Honey-buzzard density and reproduction in the area....
Article
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The joint effects of interacting environmental factors on key demographic parameters can exacerbate or mitigate the separate factors’ effects on population dynamics. Given ongoing changes in climate and land use, assessing interactions between weather and food availability on reproductive performance is crucial to understand and forecast population...
Article
Full-text available
In raptors with biparental care but sex-specific roles, adults are facing a trade-off between food provisioning and protection of the brood at the nest against predation and adverse weather. We followed the breeding cycle of a pair of Honey Buzzards in the north of the Netherlands with camera traps at their nest sites in 2015 and 2016. We monitored...
Article
Food shortage challenges the development of nestlings; yet, to cope with this stressor, nestlings can induce stress responses to adjust metabolism or behaviour. Food shortage also enhances the antagonism between siblings, but it remains unclear whether the stress response induced by food shortage operates via the individual nutritional state or via...
Article
Full-text available
The parental investment of a long-term bigamous Buzzard pair was compared to that of a monogamous pair (in fact, two pairs, as the one covered during the nestling stage was another than the one used for the incubation period), using time-laps webcams. The number of observation hours amounted to resp. 192 h and 174.3 for incubation and nestling stag...
Article
Full-text available
On 1 August 2014, an adult female Honey-buzzard visited a small Frisian village where she depredated a wasp nest in a garden and was recorded flying towards an unknown nest site. That same day, an hour later, probably the same female returned. The wasp nest was staked out with a wildlife camera. An adult female was again seen on 2 August, but for a...
Article
Full-text available
A comparison of colour morphs of breeding Buzzards in Switzerland (N=35, based on observations in 2013) and the northern Netherlands (N=91, in 2010-13) showed that on average Swiss Buzzards were less variable and darker than Dutch Buzzards. In fact, no light morph Buzzards were recorded in the Swiss sample.
Article
Full-text available
A dark female Buzzard was found emaciated in Friesland on 12 November 2012, and died two days later;; this bird had been ringed as chick on 26 June 1989 and reached an age of 8542 days (23 years old). Another dark female Buzzard was captured on a bal-­chatri in Friesland on 8 December 2012, presumably a local breeding bird (known by local raptorphi...
Article
Full-text available
On 27 april 2011, a Buzzard nest in the northern Netherlands was found to contain two Buzzard eggs (58.58x43.71 mm, 57.72x43.25 mm) and a single Goshawk egg (60.79x44.93 mm). An occupied Goshawk nest at some 100 m distance, checked on the same date, contained two eggs (59.07x44.97 mm, 58.82x44.33 mm). This latter nest turned out to have failed when...

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Projects

Projects (3)
Project
The population of Honey-buzzards is monitored yearly in an area of approximately 250 km2 in the south-east of the province of Friesland, The Netherlands. Individuals are tracked by using individual plumage characteristics by photographing, and color ringing. Diet, parental behavior and reproduction is studied by using camera traps at the nest sites.
Project
Camera traps were installed at common buzzard nests of polygamous and monogamous pairs to compare the parental behavior in both strategies.
Project
We investigate mechanism influening population dynamics in an increasing raptor species, the Red Kite (Milvus milvus), in Switzerland. Main project topics are: 1. Dispersal and settlement of the young along elevational gradients 2. Effects of natural and anthropogenic food supply on breeding success and settlement 3. Exploratory and migratory behaviour in the course of the life cycle 4. Mortality in different stages of the life cycle 5. Effects of spatial environmental gradients on population dynamics We are following the life-histories of 300 juvenile and 70 adult Red Kites by nest monitoring and GPS tagging.