Two sub-species of chiff chaff.
Phylloscopus collybita -- tristis (left) and abietinus (right). Abietinus is quite common in Norway and breeds here, whereas tristis is the Eastern sub-species often seen here in the autumn.
Interesting autumn with owls and large numbers of chiff chaffs
All mist nets were taken down on the 15th of November, and this marks the end of autumn season for the standardized mist netting and bird ringing at the observatory. The ringing totals for autumn season ends at 6624 birds distributed over 73 species. Autumn 2011 stands out as a record season for owls. It has also been a good year for raptors, and birds that are normally not caught in the mist nets have been ringed and logged at the observatory. We have also seen an unusual number of chiff chaffs and blue tits this season.
Mist nets are dismantled before the winter.
Long-eared owl (Asio otus)
This long-eared owl was caught in a mist net in the labyrinth during one of the last days of the season.
Chiff chaffs ringed, autumn 1990-2011
The number of chiff chaffs has more than doubled since last year, and lies well above the average. The standard deviation is ~19, hence the number of chiff chaffs this season is almost 5 times higher than expected.
Blue tits ringed, autumn 1990-2011
The blue tits have had a few good years lately. If the trend with two good years followed by a sharp population decline continues, we will see significantly fewer blue tits next autumn.
By M. Wold
The ringing total of 6624 is just slightly below the total of 6844 for autumn season last year. The number of controls this season is 535, with willow warbler as the species with most controls (84).
Good autumn for owls and raptors
The ringing total for Tengmalm's owl is 204, distributed over 20 days. Last time the observatory experienced similar conditions was 15 years ago when a total of 198 Tengmalm's were caught and ringed during 28 days of mist netting. A nice surprise at the end of this years season was a long-eared owl, the second in the history of the observatory. The autumn season overview of owls in the ringing room follows:
|Tengmalm's owl(Aegolius funereus)||204|
|Pygmy owl (Glaucidium passerinum)||42|
|Tawny owl (Strix aluco) ||2|
|Long-eared owl (Asio otus)||1|
One of the most noteworthy trends with the ringing numbers this season is the large number of raptors caught in the mist nets. In total, we have ringed six sparrow hawks, as well as both common buzzard and kestrel. The common buzzard makes the first for the observatory, and it is also not every year that great grey shrikes are caught and ringed. This year we ringed three of them.
Unusual large number of chiff chaffs and blue tits
There has been a significant increase in the number of chiff chaffs in comparison to previous years, as seen in the graph on the right-hand side. The number of chiff chaffs ringed is 85, and lies well above the average of 35.5 over the last 22 years. We have also seen an unusual number of blue tits the last two autumns: more than 2000 were ringed this year, and 1782 last year over the same period. The blue tit histogram on the right-hand shows a possible pattern over the last few years with two good years followed by a steep decline in the population. If this trend continues, autumn 2012 will be less dominated by blue tits.
Top ten from the ringing room autumn 2011, compared to same season the year before:
|Art||Høst 2011||Høst 2010|
|Blue tit (Cyanistes caeruleus)||2255||1782|
|Willow warbler (Phylloscopus trochilus)||786||872|
|House sparrow (Passer domesticus) ||330||250|
|Chaffinch (Fringilla coelebs)||255||300|
|Blackcap (Sylvia atricapilla) ||221||133|
|Great tit (Parus major)||213||194|
|Tengmalm's owl (Aegolius funereus) ||204||1|
|Coal tit (Periparus ater)||198||75|
|Meadow pipit (Anthus pratensis) ||148||86|
|Robin (Erithacus rubecula)||145||226|
Invasion by two-barred crossbills
Also noteworthy this autumn has been an invasion of two-barred crossbills, something that has not been seen since 2002. The two-barred crossbills appeared at the end of July, and are still observed in the plantation next to the observatory where they reside together with a larger flock of common crossbills. The total number of sightings in August was 625 with approximately 40-50 per day. Now, by medio November, we register typically 4-8 per day. In comparison, during all of 2010 only two were registered.
Welcome back next year
The observatory wishes to thank everyone that has contributed to our efforts with both ringing and logging this autumn. Also a big thank you to the observatory's ringer Richard Cope who has left for London and will spend a well-deserved winter holiday in his home country. Welcome back next year!
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