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2015 - All time low for migrating passerines

Lista Bird Observatory has been monitoring passerines using standardized catching with the aid of mist-nets for 25 years. We are now halfway through the autumn season, which for the ringing station is from 15th July to 15th November. As the majority of insectivorous passerines have now left Norway, we can make a preliminary conclusion. The conclusion is easy to draw: the first part of autumn 2015 has been the poorest since the observatory started in 1990 for warblers and other long-distance migrating passerines at Lista B.O. The situation is expected to be the same for species that migrate shorter distances later in the autumn as well.

Lista Bird Observatory has been monitoring passerines using standardized catching with the aid of mist-nets for 25 years. We are now halfway through the autumn season, which for the ringing station is from 15th July to 15th November. As the majority of insectivorous passerines have now left Norway, we can make a preliminary conclusion. The conclusion is easy to draw: the first part of autumn 2015 has been the poorest since the observatory started in 1990 for warblers and other long-distance migrating passerines at Lista B.O. The situation is expected to be the same for species that migrate shorter distances later in the autumn as well.


By Jan Erik Røer
The lowest numbers for many species
The low numbers of birds in the nets, is applicable to most of the species included in the table below . Whinchat, Garden Warbler, Blackcap, Willow Warbler (Picture at top of page) and Spotted Flycatcher show so far the poorest season since we started the standardized ringing (in 1990). Regarding these species, more than 95% of our breeding birds normally migrate before 15th September. In addition, both Tree Pipit and Starling numbers are very close to the lowest numbers we have observed previously.

On the other hand, there are some other species, such as Dunnock, Robin and Chaffinch, where preliminary results, albeit early in the migration season for these, indicate that we have to date recorded lower numbers than ever before.

The Autumn netting campaign is dominated by juveniles
Normally there is a large predominance of juveniles among the caught birds in the autumn at the bird observatory. Adult birds (1 year and older) migrate for most species more directly and probably more so over Lista during autumn migration. Therefore, the autumn figures from the bird observatory mainly reflects the number of juveniles in the station's recruiting area for the breeding season. The catch data can explain how successful the breeding season has been. With generally low catch figures this year, it seems that most passerine bird species have had a very poor breeding season, with few chicks that have survived until the autumn migration.

Species / Date No. of caught birds 2015 Average 1990-2014 ± %
Willow Warbler Phylloscopus trochilus 225 550 -59 %
Stasling Sturnus vulgaris 69 155 -55 %
Chaffinch Fringilla coelebs 46 132 -65 %
House Sparrow Passer domesticus 56 81 -31 %
Wheatear Oenanthe oenanthe 34 76 -55 %
Garden Warbler Sylvia borin 18 66 -73 %
Whitethroat Sylvia communis 35 65 -46 %
Linnet Carduelis cannabina 89 61 46 %
Blackcap Sylvia atricapilla 15 57 -73 %
Trepiplerke Anthus trivialis 20 49 -59 %
Robin Erithacus rubecula 14 45 -69 %
Meadow Pipit Anthus pratensis 33 44 -24 %
White Wagtail Motacilla alba 43 43 0 %
Tree Sparrow Passer montanus 6 36 -83 %
Blue Tit Cyanistes caeruleus 2 34 -94 %
Dunnock Prunella modularis 9 33 -73 %
Goldcrest Regulus regulus 12 31 -62 %
Green Finch Carduelis chloris 12 28 -56 %
Lesser Whitethroat Sylvia curruca 15 27 -45 %
Yellowhammer Emberiza citrinella 7 27 -74 %
Whinchat Saxicola rubetra 5 26 -80 %

The table shows 21 species, which normally are caught in the nets with numbers exceeding 25 individuals until 15th of September, under the standardized ringing programmme at Lista Bird Observatory. First column of figures shows the annual catch numbers, while the next column shows the average for the period 1990-2014. The last column shows the catch percentage compared to the average in the same time period.



A cold and wet spring, together with a lot of snow in the mountains, resulted in poor breeding success.
The main reason for the poor breeding season seems to be quite obvious: A cool spring and an early summer, combined with relatively much rain. These weather conditions meant that parents could not find enough food, leading to high nestling mortality and very low breeding success. After a mild April in large parts of Scandinavia, the temperature in May and June dropped far below normal. The result was that insect larvae (especially butterfly caterpillars) did not evolve, or their cycles were delayed. In addition to this problem, the parents had extra energy demands in warming up eggs and chicks during low temperatures and frequent rain. The weather made foraging difficult, which did not allow many passerines to find enough food.

Many people reported during in the social media in late June that they had found their nest-boxes full of dead nestlings. These reports came from all over southern and central Norway, but also from Sweden. The clutches were mainly from Blue Tit and Great Tit. The situation was probably better with Pied Flycatcher which breed a little later than the tits. The results from Lista now suggest that the poor breeding season affected many more species than just tits.



From Finse 1st July 2015. Not many places to nest here. Finse is 1222 meters above sea level, but it was significant with snow very late, also at lower altitude than this. Photo Jan Erik Røer.


While in the low altitude rain and cold temperatures made it difficult to nest, in the mountains and especially west of the watershed, the snow in many areas hardly melted before breeding season was over. As an example the ground was completely covered with snow at Finse as late as 1st July. It was not only difficult for Willow Warblers and Meadow Pipits to nest in many places here, but rather it was quite simply impossible. In addition, rodent populations collapsed in southern Norway during the winter 2014/2015. This normally results in several predators turning from rodents to instead feed on eggs and nestlings. The few chicks that were able to leave the nest, probably experienced a greater predation pressure.


Poor mist-netting conditions, but few birds in the nets anyway.
During recent years, late summers and early autumns at Lista have been windier than normal. These are difficult mist-netting conditions meaning sometimes that fewer nets can be opened and thereby resulting in less birds caught in the nets. However, when the conditions have been good, the number of bird in the nets has also been low. We have experienced several windless days almost without any birds on migration or in the nets.

Our results from Lista are also not very different from other reports this autumn. Jomfruland Bird Observatory states in its’ August report that they only ringed 236 Willow Warblers in their standard programme compared to the normal average of 874. while a number other species were also caught in lower numbers than normal. Falsterbo Fågelstation in Southern Sweden had as of 14th September, trapped 1834 birds compared to the normal average of 2,981 birds. At Falsterbo Willow Warblers were caught in numbers only had half the normal average, and European Robins just a third of the normal average. There are however species that occurred in more normal numbers at Falsterbo. Low numbers of birds ringed were also reported from Ottenby on Öland, although we do not at present have more details from there.



Dead clutch of Blue Tits from Nesodden, Akershus County on 5th June 2015. From six clutches in this area only 4 fledglings were produced. Normally there would have been around 50 to 60. The same situation was reported from many other areas. Photo: Jan Erik Røer


Probably not any better for short-distance migrants
With a very weak start for Chaffinch, Dunnock and Blue Tit, there is reason to assume that the rest of the autumn will be more of the same. So far this autumn, there have been very few irruptive species moving through. Since the irruptive species migrate when the population peaks, it is quite natural that they are not on the move when the nesting season probably has been unsuccessful. We therefore do not expect good number of Blue Tits, Coal Tits , Willow Tits or Long-tailed Tits during the remainder of the autumn, but there is always a possibility that influxes may result from populations breeding farther east.

You can follow this season's monitoring on our website:
Season data from standardized netting - Lista Bird Observatory





The figure shows the number of Whinchats in the constant effort mist-net monitoring at Lista Bird Observatory up until today’s current date. As of 15th September only five Whinchats had been caught, which is only 20 % of normal average and far below 10 % of the peak years in 1990 and 2002




The north-western climate is harsh for passerine breeding birds
Swedish studies have shown that nesting birds north and west in Sweden have declined over the past decade, more than in the warmer south-east. This fits well in to the pattern of this summer, because it is in the north and west we see the strongest effects of a wet and cold summer climate.

In principle, this pattern is well known, as many insect and bird species hves a distribution boundary between Vest-Agder and Rogaland in Southern Norway. The wet summer weather on the west coast is too tough for many species.





This article reviews the results of monitoring of passerines at Lista Bird Observatory, as these dominate in the stadardized mist-netting programme. These birds come mainly from southern Norway. Other species groups other than passerines seem to have fared better. Waders, most of which breed in locations far from southern Norway have done well. This young Sanderling from Skarvodden at Lista could have jumped between all of the rocks free and happy if it wasn’t for all the birds of prey in the area. Photo: Jan Erik Røer, 25th August 2015.


Ringing numbers
This season3187
Today0
Detailed log

Reportasje fra Lista FS
i Aftenposten

Seasonal deviation
Eurasian Jay9-99%
European Reed Warbler3-96%
Hen Harrier2-96%
Northern Fulmar76-96%
Northern Shoveler1-95%
Parrot Crossbill726+7590%
Black-tailed Godwit66+445%
Mute Swan249+408%
Crested Tit230+398%
Ruff1926+305%
View deviation of seasons
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Siste 5 på siden
  LISTA FUGLEFESTIVAL 2017
  Tick project at Lista Bird Observatory
  Fuglefestival 2.-3.sep. PROGRAM
  Report from spring 2017
  Population monitoring at Jomfruland and Lista Bird Observatories in 2016

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