Surveillance of Autumn Migrating Cranes Grus grus, in Nord-Trøndelag, Norway, 2002

 

Work Report for 2002

 

Per Inge Værnesbranden

Trøndelag Tranegruppe

 


 

 

Summary:

The count of autumn migrating cranes in Nord-Trøndelag during autumn  2002 showed at least 1100 cranes, which is the highest number since the counts started in 1999. The maximum was reached medio September, between the dates 13.-19. At some roosts the numbers was very variable, like in Verdal og Figgadalen, while in Overhalla the number of cranes kept relatively stable. In Klingsundet, Figgadalen and Ronglan the cranes left the areas at early dates. The strong increase in Verdal, with minimum 388 individuals, can indicate that cranes from Figgadalen have made a stay here after leaving Figgadalen. The last cranes was seen in Overhalla on Oct. 5th. Three colour-ringed cranes was seen in Snåsa and Stod, all ringed in Orkdal/Meldal/Rindals-areas. Migrating flocks was seen heading east / south-east in Verdalen (Skjækerfossen, Kråksjøen and Sandvika) and at Feren, Meråker. No new night roosts were found. An attempt with airplane counts showed to be more demanding than expected, and will only exceptionally be used at later occasions.

 

 

Introduction

The project ”Surveillance of Autumn Migrating Cranes in Nord-Trøndelag” has been proceeding for four years. This years counts was the last count where the roosting sites was counted weekly during the whole of September, and until the last crane was registered. These counts also included the National Crane Count during the weekend of September 21th – 22nd. The counts were supported from Wildlife Funds from the County Governor of Nord-Trøndelag, Environmental Dept. In addition to counts on ground, counts from airplane were attempted twice, September 15th and 22nd. In Sør-Trøndelag counts were also carried out likewise.

 

 

Locations in Nord-Trøndelag

 

Overhalla

In contrary to earlier counts the coverage was relatively good in 2002, with counts every weekend in September and the first in October. Like before, the cranes kept mainly between the Overhalla centre and Skage, on both sides of the river Namsen. The average number of cranes pro count was 346 individuals in September, while the last weekend gave 33 cranes on October 5th. The highest number was 396 individuals on September 14th. This was probably a minimum as it is difficult to achieve optimum coverage. It was not possible to determine accurate number of 1st years or brood sizes for the total number of cranes. The highest number of 1st years was 43 (11,2 % of 385 ind.)  September 7th. Largest number of single-broods was 27 on September 7th, while seven twin broods was registered on September 1st. This gives 34 pairs with succesful nesting. The flock size varied much between each weekend count. The largest flock was 342 individuals on September 1st, cranes was not seen anywhere else on this date. The counts in Overhalla was performed by Arne Vanebo, Stig Jønsson and Per Inge Værnesbranden.

 

Snåsa

Four counts was made before the cranes disappeared. The cranes in Snåsa stayed in the area at Gran and Granabukta. Flock size was between 13 and 66 cranes. Largest nuber was registered on Sept. 9th, with 66 individuals, the accurate number of 1st years was not registered. Totally 3 broods with one young and 2 broods with twins were observed during the counting period. Last date with registrations was Sept. 22nd. All counts in Snåsa was made by Pål Mølnvik

 

Klingsundet

In the area Klingsundet/Stod five counts were done while the cranes was present. The cranes were mostly on the Stod side, especially at Gusthaugen, but were also seen at Kvam on the north side and in the sound itself. Largest number was at least 170 individuals September 15th, and these were registered during airplane counts (see below). This is also the largest amount of cranes registered in the area since autumn counts started in 1999. Largest count of 1st years was seen Sept. 15th, with five broods with single young and four twin broods in a flock of 127 individuals. Last date with cranes was Sept. 22nd, while no cranes was present on the 29th. Counts was performed by Arne Vanebo, with supplementary data from Erik Torp.

 

Figgadalen

In Figgadalen the cranes dissapeared early, the last ones was seen on Sept. 14th. No cranes was seen the day after, nor at the 22nd or 29th. These birds have probably moved to Verdalen (see below). Four counts exists from Figgadalen in September, but the figures are varies (17, 151, 190 and 117 individuals). Last weekend with observations 190 individuals was seen in flight Sept. 13th (E. & K. Svepstad notified PIV) and 117 individuals Sept. 14th, none Sept. 15th. Largest amount of juveniles was Sept. 7th, with 12 juv. (broods and sizes unknown) of 151 individuals. The counts was performed by Arne Vanebo, with supplementary data from Else and Kåre Svepstad and Per Inge Værnesbranden.

 

Verdal

In the Verdal area the number of cranes was very varying, probably due to the fact that traditional roosting areas was not used as extensively as usual. Ca. 200 individuals was seen at Volen Sept. 4th, while ”only” 42 individuals was seen Sept. 8th – 9th in the area Stiklestad-Vuku. Next weekend (Sept. 14th – 15th) 149 individuals was registered in the same area. Sept. 18th at least 388 individuals was seen in flight up the Leirådal, highest ever number in Verdalen. The next day there were 308. This significant increase is probably because cranes has migrated from Figgadalen and possibly Klingsundet. largest number of juveniles was 24 juv. of 182 cranes Sept. 22nd, with 14 single broods, and five twins. The counts in Verdalen was carried ouy by Halvor Sørhuus ans Børge Botnen,  supplementary counts by Roar Rismark and Arne Vanebo.

 

Ronglan

From the Ronglan/Skogn-area only small numbers was registered in early September (15 individuals), while the largest number this autumn was reached the following weekend, with 80 individuals Sept. 6th. Here 10 juveniles was registered, with three single broods, two twins and one triple, which is quite unusual. The next weekend, Sept. 14th, 62 individuals were registered, whereof six single broods and one twin brood. Last date of registration was Sept. 15th, with 45 individuals (airplane count). Neither on Sept. the 22. or 28. any cranes was seen. The counts were made by Magne Husby and Per Inge Værnesbranden.

 

Stjørdal

In Stjørdal the number varies from 28 - 65 individuals. The birds was found in the area Øfsti south of the river, Moanes and Kartum to the north and Hegra. Maximum was Sept. 15th with 65 individuals, whereof four single broods. Last date was Sept.  29th, with 28 individuals. On Oct. 6th no cranes was left. All counts was performed by Per Inge Værnesbranden.

 

Other locations

Apart from single families found outside roost, migrating flocks were found heading East/Sout-East in the border areas, and most probably all came from the roosts in i Verdal. 46 cranes heading East, at Langsåa, Feren, Meråker Sept. 29th (Tom Roger Østerås). Sept. 25th 13 individuals flew South-East at Skjækerfossen, Verdal (Inge Storholmen). Oct. 3rd, two flocks reported, one of  70 individuals heading south at Sandvika, Verdal (Asle Buran) and 40 individuals towards South-East over Kråksjøen, in direction of Storsjøen (on the Swedish border), Verdal (Jon Arve Husby).

 

Night roosts

No new nigth roosts according to what was known from earlier years.

 

 

Table 1. Maximum weekly numbers for each location in Nord-Trøndelag in 2002.

 - means no count performed in actual period.

0 means location visited without cranes seen.

 

Week 35

26.8-1.9

Week 36

2-8.9

Week 37

9-15.9

Week 38

16-22.9

Week 39

23-29.9

Week 40

30.9-6.10

Week 41

7-13.10

Overhalla

342

385

396

307

300

31

-

Snåsa

51

47

66

47

0

0

-

Klingsundet

106

144

170

61

0

-

-

Figgadalen

17

151

190

0

0

0

-

Verdal

-

200

149

388

150

0

-

Ronglan

15

80

62

0

0

-

-

Stjørdal

40

48

65

35

28

0

-

Other loc.

-

-

-

46

17

110

-

Sum NT

648

1094

1138

925

537

185

-

 

 

Table 2. Some key figures for each location. See text for details

 

Date for max no.

Max. no. cranes

% juveniles

1-brood

2-brood

3-brood

Average brood size

Date last reg.

No. of Counts

Overhalla

14.9

396

?

?

?

-

?

5.10

6

Snåsa

14.9

66

0

0

0

-

0

22.9

5

Klingsundet

15.9

170

?

?

?

-

?

22.9

4

Figgadalen

13.9

190

?

?

?

-

?

14.9

4

Verdal

19.9

388

?

?

?

-

?

26.9

6

Ronglan

6.9

80

12,5

3

2

1

1,67

15.9

3

Stjørdal

15.9

65

6,15

4

0

-

1

29.9

5

Other loc.

 

0

 

 

 

 

 

15.10

 

Max. no. cranes = number of cranes counted at each location at one time.

No. of broods and %-percentage juveniles = the number of broods is separated on size. The highest value of single or twin broods is used.

Date last reg. = date for last registration is given. This is not necessarily equal to the departure time for the majority of birds. See comments under each location in the article.

 

 

Airplane counts

New this year was the attempt to count from airplane. Originally one count was planned during the national count weekend, but one count was made the previous weekend as well. A hired light-craft airplane flew from Værnes Airport and visited all the locations. All the found flocks was photographed and the pictures was counted afterwards. Airplane counts were performed by Per Inge Værnesbranden (Sept. 15th) and Georg Bangjord (Sept. 22nd), with pilot Geir Sommervold.

 

The post-flight conclusion is that airplane counts is not suited for this purpose. The cranes can be difficult to spot on ground at long distance. Ground counts were performed parallell to the airplane counts, and on most occasions the ground counts gave the better results. Only at Klingsundet the number of cranes was higher when using airplane. However, airplane counts can most likely be performed at some locations later.

 

 

Registrations of colour-ringed birds

Also during autumn counts 2002 colour-ringed cranes were found. A juvenile ringed at Lia, Løkken, Meldal in 2000, was seen Sept. 1st and 9th at Snåsa (Pål Mølnvik). In Stod two colour-ringed cranes were seen (Arne Vanebo): one juvenile ringed in Husdalen, Orkdal in 2001, was seen at Lillevestre Sept 1st and at Gusthaugen, Stod Sept. 9th. One juvenile ringed Lomunddal, Rindal in 2001, was also seen at  Lillevestre Sept. 1st.

 

 

Acknowledgements

Many thanks go to all participants or whom in any form supplied with information. These are named under each location. Especially to be brougth forward is Arne Vanebo, which performed the majorty of counts in three areas, Overhalla, Klingsundet og Figgadalen. Pilot Geir Sommervold is thanked for the good cooperation during airplane counts.