Part 2: The end of the “Nightjaring” season is approaching

Late in season the Nightjars appear to be less territorial and are successfully trapped in so called “Nightjar hot-spots”, (which for an untrained eye probably look like random places in the forest). When the activity is good one may even catch “a few” birds at the same time!

The Nightjars have, as most other birds, stopped singing (or rather “churring”) which is an evident sign of the end of the breeding season. Some Roe deer, Foxes and grumpy Wild boars occasionally break the silence in the forest, and in the early (or late?) hours one may hear the sound of a single Pygmy owl welcoming the first morning light. The Nightjars are however still out there and we trap quit a few of them, which gives us the opportunity to collect data on the timing and extent of for example their post-breeding feather moult and pre-migratory fuelling. These factors are likely influencing the timing and characteristics of the autumn migration and will be useful complement to the GPS-data (that we are planning to retrieve next year) in revealing strategies used by the birds. Data from the geolocators suggest that many Nightjars may already have started their migration to the wintering areas, but birds ringed within the study area earlier in this season are still encountered during our trapping sessions. These birds are of extra interest when we can track the transition from breeding to migration in e.g. fuel load on an individual level. It also gives us hope to still retrieve additional geolocators from earlier seasons.
A 10 day old Nightjar chick is ready to be ringed.
As late as two weeks ago we found active nests of Nightjars and we have successfully trapped and ringed the chicks and their parents. To our surprise we also found a second nest for the season of one female about 100 meters from the first one. This bird was an old acquaintance that we trapped on the same spot in 2013. Female Nightjars are known to be able to lay two clutches in one season, either with the same male or with a second one, while the first male solely takes care of the first clutch. This was however the first time we observed it in our study area. Unfortunately we were not able to reveal if the male of the second clutch was one of the three (!) males trapped at the first nest or someone else. Nightjars are thought to be monogamous, at least within each clutch, but apparently there is a lot more to learn also in the birds´ social life.
//Gabriel Norevik

If you missed Gabriels first blog post  - it is found here:
"Spending some summer nights with European nightjars"

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