The total number of Crex crex recoded in the floodplain territories of the project in 2008 was slightly lower than in 2007 that was the highest since counts of the species in the territory was started (fig. 1). Nevertheless, the overall trend of the species remains positive (S=1.0255±0.0319), however, it is not statistically significant and thus should be regarded as “uncertain”. Comparing the population changes in the project sites with the national population indices of the species (fig. 2), it is obvious that the drop of the Corncrake population in 2006 and its increase in 2007 had been observed not only in the project territories but also in the whole species population of the country. However, the Corncrake population in the project territories experienced smaller drop and higher increase than in the rest of the country.
Number of corncrakes has either been stable (fluctuating) or rising in all of the project areas except Vidusburtnieks 2 (see reasons explained in the account of this site). Collected data suggests that there is a connection between the vegetation height in the beginning of the breeding season and the density of Crex crex. Higher vegetation increase density of calling males thus suggesting that too late mowing can reduce Corncrake numbers in the next breeding season.
Population changes suggest that project has reached its goal – stopping decline in the floodplain population of Crex crex that was going on due to overgrowing of their habitats.
Figure 1. Changes of the yearly maximum counts of Corncrakes Crex crex counted in the project areas
Figure 2. Changes of breeding population index of Corncrake Crex crex in Latvia (1989 – 2007; dotted line; Keišs unpublished) and the LIFE territories (2005-2008; solid line; project data)
Numbers of Porzana porzana are fluctuating pronouncedly between the years (fig. 3). This can be explained with the fact that singing activity peaks when the species is best detectable are rather short and their timing is also fluctuating between the years and sites. These fluctuations are connected with moisture conditions in the meadows. There is a high probability that the numbers recorded in counts reflect a rather small proportion of the birds present in the study areas and this proportion varies noticeably between the years. Thus no reliable conclusions can be drawn on population changes of this species in the study sites. Possibly an earlier additional count (early May) would yield better and more stable figures for this species (and also for Common Snipe), however, numbers recorded in this period might contain unknown number of passaging birds as this coincides with the maximum of the spring migration of this species.
Figure 3. Changes of the yearly maximum counts of Spotted Crake Porzana porzana counted in the project areas
The yearly maximum of Gallinago media recoded in the floodplain territories of the project in 2008 was marginally lower than the highest count of the species recorded in 2008 (fig. 4). Although the overall trend is clearly positive (S=1.1165±0.0727), it is not statistically significant yet due to large confidence interval and thus should still be regarded as “uncertain”. If compared with the national trend of the species (fig. 5), where a “moderate decline” (S = 0.9543± 0.0189, p<0.05) has been recorded since 1999, the increase in numbers in the project territories should be regarded as a success. The success achieved in the project territories should also be regarded as a possible reason for improvements in the national trend as project areas hold ca 50% of the national population of Gallinago media.
Numbers of Great Snipes have either been stable (fluctuating) or increasing during the project period. There are no territories with a constant downward trend of the species. The most notable increase in numbers has been recorded in Ruja floodplains and Burtnieki meadows where large areas of the species habitat have been restored.
Population changes suggest that project has reached its goal – stopping decline in the population of Gallinago media that was going on due to degradation of their habitats. Even more, due to project activities trend of the species has been reversed not only in project areas but also in the whole country.
Figure 4. Changes of the yearly maximum counts of Great Snipe Gallinago media counted in the project areas
Figure 5. Changes of breeding population index of Great Snipe Gallinago media in Latvia (1999 – 2008; dotted line; Auniņš unpublished) and the LIFE territories (2005-2008; solid line; project data)
The yearly maximum of Gallinago gallinago recoded in the floodplain territories of the project in 2008 was slightly higher than in previous two years but still substantially lower than in 2005 (fig. 6). Although the overall trend is negative (S=0.9454±0.0644), it is not statistically significant and thus should be regarded as “uncertain”. Also the differences between any two of the years were not statistically significant. The tendency is generally opposite to that of Great Snipe. One of the possible explanations for the observed decline is inter-specific competition as Great Snipe uses largely the same resources as the Common Snipe.
Figure 6. Changes of the yearly maximum counts of Common Snipe Gallinago gallinago counted in the project areas
Locustella naevia after a peak in numbers in 2006 has been continuously declining reaching its three year minimum in 2008 (fig. 7). The difference in numbers between 2007 and 2008 is significant (Z=-2.123, p=0.034). Although the overall trend value suggests it is stable, due to the large confidence intervals trend should be regarded as “uncertain” (S=1.0004±0.0434, p<0.05).
The change pattern of this species in the project territories is markedly different than the one observed in the whole country (fig. 8). The species has pronouncedly increasing long term tendency in the due to overgrowing of abandoned agricultural lands which had stabilised or slightly reversed since 2003 and then experiencing again a peak in 2007. The differing change pattern in the project territories suggests that these changes have mostly been influenced by local, site specific factors. The increase in numbers between 2005 and 2006 was possibly caused by increase of suitable habitat. As species prefers abandoned grasslands which have started to overgrow with bushes while avoids too overgrown areas, the initial removal of bushes in such areas can increase the numbers of this species. However, with introduction of regular mowing and decreasing amount of shrub re-growths in these areas its numbers continuously decline. This is most likely explanation of the observed changes in the project areas.
Figure 7. Changes of the yearly maximum counts of Grasshoper Warbler Locustella naevia counted in the project areas
Figure 8. Changes of breeding population index of Grasshopper Warbler Locustella naevia in Latvia (1995 – 2008; dotted line; Auniņš unpublished) and the LIFE territories (2005-2008; solid line; project data)
The yearly maximum of Locustella fluviatilis recoded in the floodplain territories of the project in 2008 was the lowest since counts of the species in the territory was started (fig. 9). Although the trend is slightly negative (S=0.9862±0.0382), it is not statistically significant and thus should be regarded as “uncertain”. The observed changes in actual numbers are not large and are ranging between 160 and 200 pairs recorded during the counts.
The change pattern of this species in the project territories is slightly different than the one observed in the whole country (fig. 10). The species had been declining in agricultural lands of the country since late 1990-ies. The countrywide decline continued also during the project years. However the numbers in the project sites were rather stable or slightly growing. The change pattern varied between the territories and there were territories with gradual increase as well as gradual decline observed in numbers of this species and these differences were not related with management activities carried out. These results are rather surprising as the species is associated with large bushes. However, the drop in numbers in 2008 suggests that we had observed a time-lag in the species response.
Figure 9. Changes of the yearly maximum counts of River Warbler Locustella fluviatilis counted in the project areas
Figure 10. Changes of breeding population index of River Warbler Locustella fluviatilis in Latvia (1995 – 2008; dotted line) and the LIFE territories (2005-2008; solid line; project data)
Coturnix coturnix. Species has experienced substantial changes between the years during the project period. After a drop to zero in 2006, the all time maximum was recorded in 2007. Then in 2008 numbers dropped again to similar as recorded in 2005. No conclusions can be drawn from such a scarce data as stochastic variation has significant effect on counts of species with low detection probability. After a peak in numbers in 2007, near significant drop in numbers was recorded in 2008 (Z=-1.933, p=0.053).
Figure 11. Changes of the yearly maximum counts of Quail Coturnix coturnix counted in the project areas
Sita and Pededze flodplains. The most part of this territory underwent large scale restoration activities during the project. Although the most prominent changes took place between 2005 and 2006, the landscape, especially in the northern part of this territory, changed considerably also in the period between the following breeding seasons.
The last breeding season (2007) was as good for Gallinago media as it was in 2007 –these are the peak years for this species in this territory since the monitoring of Great Snipe leks started in 1999. In difference to the situation in 2007 the birds from the 3 leks (2007) were concentrated in a single large lek (2008). This is obviously related with moisture conditions in the meadows during the breeding season of 2008 which was extremely dry. Numbers of Crex crex have been stable for this territory during the project period ranging from 41 to 46 in the best counts of the season. The numbers of Gallinago gallinago rised if compared to 2005 and the most significant jump in numbers was between the breeding seasons of 2005 and 2006 when most restoration activities took place. The numbers of both Locustella warbler species dropped compared to the beginning of the project.
Mugurve meadows. The extent of changes in habitats due to management has not been as prominent as in the neighbouring site “Sita and Pededze floodplains” (see above) thus the factors that are non site-specific played greater role on populations of the target species. The numbers of Crex crex was lower in 2008 than in the previous year which was a general tendency for all sites in this year. Due to the extremely dry breeding season in 2008, no Gallinago media were recorded in the territory. The effect of the changes in habitats is best reflected by the two Locustella warbler species – both are slightly declining in this territory as a result of reduced shrubby and overgrown areas available for them.
Although slight decline of Gallinago media was recorded in 2008, however the number of lekking males found in previously known lekking area was close to number as in two previous years. Decline of the total number of Gallinago media observed was associated with lack of lekking ‘satellite’ males in a vicinity of main lekking area. Like in 2006, also in 2008 Gallinago media experienced low number during 2nd counting.
After a peak in numbers in 2005, a drop to zero in the all next years was recorded in numbers of Porzana porzana. Most likely these changes cannot be explained with meadows management, but is associated with flood conditions (i.e. meadows moisture) in particular years.
After a peak in numbers in 2007, a drop in numbers of Crex crex, Locustella fluviatilis and Locustella naevia was recorded in 2008. As large part of this territory underwent restoration activities, decrease in numbers of these species cannot be associated with quality of breeding habitat. Because similar decrease was recorded in other (south)eastern territories (i.e. Mugurve meadows), it is believable that there were some regional peculiarities in phenology or distribution of these species.
Burga meadows. A large part of this territory underwent restoration activities between the breeding seasons of 2005 and 2006 while comparatively small changes occurred between 2006 and 2008. Most of the recent changes took place on the left bank of the Seda river The number of Crex crex that had been continuously declining in this territory until 2007 markedly increased in 2008 reaching the level of 2005. Number of Great snipes was growing until 2007 and experienced a slight drop in 2008. Although the numbers of both analysed warbler species declined as expected until 2007, in 2008 their numbers markedly increased. There were no changes in the population of Common Snipe during the project period.
The reason of the initial Corncrake and Grasshopper Warbler decline, possibly, was the very late mowing (usually September). As a result, there is very short vegetation in next May in these places, and this means that there is no vegetation cover for the species. As in 2006 also in 2007 significantly more Corncrakes were recorded in the 2nd count when the new vegetation had reached considerable height. After mowing the meadows in July 2007, increase of Corncrake and Grasshopper Warbler numbers in 2008 was noticeable as was the height of vegetation in May. This also might be the reason of the slight decline of Great Snipe as the moist soil where the species feeds was less accessible than before.
Meadows of Seda River. Most part of this Project site had undergone restoration activities either by removal of bushes or introduction of mowing between the breeding seasons of 2005 and 2006 while comparatively small changes occurred in the following years. 10 ha. The density of recorded Corncrakes has been very high compared to all the other territories and number of Great Snipe keeps stable. Although most of the bushes have been removed from the open part of the territory, density of both warbler species are still very high and River Warbler experienced its maximum in 2008.
Vidusburtnieks meadow 1. Prominent restoration activities took place in this territory between 2007 and 2008 – the whole overgrowing territory has been reverted to open grassland. Nevertheless these changes did not result in significant changes of any of the measured species populations yet. Corncrakes maintained their maximum reached a year ago also in 2008. As the works were ended only shortly before the breeding season this disturbance might have had an effect so that the positive benefits were not visible yet.
Vidusburtnieks meadow 2. As no management activities had taken place in this territory so far, the only change in habitats was continued overgrowing in the meadow. As a result River Warbler which is most associated with bushes had their maximum in 2008. After the continuing growth of Grasshopper Warbler population, there was a drop in numbers in 2008. It is possible that the area has become too overgrown and can maintain lower number of pairs of this species. The previously extinct lek of Great Snipes that was active again in 2007 had gone again in 2008. This was also a maximum year for the Common Snipe which is rather tolerant to bushes.
Ruja floodplains. Large areas in this site underwent restoration activities both by introduction of mowing and removal of bushes. The process started in 2005 continued until the very breeding season of 2008. Numbers of Crex crex continued to increase as was expected. Also numbers of Gallinago media increased – now there are 2 permanent leks with 20 or more lekking males in each. Both warbler species experienced a decline, especially the River Warbler whose population almost halved. This is associated with the restoration activities carried out by the project.
Burtnieki meadows. This territory consists of two well separated parts and each of them received different treatment during the project. Removal of bushes started in 2005 and continued until the spring of 2008 in the meadows along Eikenupe river while management activities along Briede river were started only after the breeding season of 2007 and carried out up to very beginning of the breeding season of 2008. Numbers of both Crex crex and Gallinago media had their maximum in 2008. There was increase also in numbers of Common Snipe and a marked drop in numbers of Grasshopper Warbler which is an effect of the late mowing in 2007.
Continuation of management (grazing) of meadows restored until 2007 eliminate impact of extremely late moving (in October 2006) and the resulting short vegetation that was observed in year after restoration. Also additional areas were restored by initial mowing and shrubs cutting until breeding season of 2008. 2008. was a first year after continuous three years decline when number of Crex crex start to increase, but their number didn’t reach their maximum recoded in 2005. The numbers of both Locustella warbler species recoded in the Lielupe floodplains in 2008 were the lowest since counts of the species in the territory were started. The changes in numbers of Crex crex and both Locustella warbler species in this territory should be regarded as a result of meadows restoration.
In this territory considerable increase in numbers of Gallinago gallinago can be linked with the favourable flood conditions that was achieved by restrictions concerning water table regulation. These restrictions were elaborated during site management plan preparation. After a peak in numbers in 2007, a drop in numbers of Crex crex was recorded in 2008. There was second year when number of Locustella naevia was continuously decreasing after a peak in numbers in 2006. Also constantly low numbers of Locustella fluviatilis should be regarded as a success achieved by shrubs cutting that has been done in left bank of Svete River until breeding season of 2006. Large dimension of meadows (both, restored by project activities and kept in favorable conditions by landowners) made this territory exceptional as only project site where Coturnix coturnix has been recorded in two running breeding seasons.
In this territory main initial mowing activities took place in 2005 and 2007. Therefore fluctuating pattern of Crex crex and Locustella naevia numbers during project rather represent impact of short vegetation at the beginning of the next year breeding season after extremely late (November) initial mowing.
As during deeper investigations presence of shrub-related biological values were found in old-growing Salix stands, location of priority areas for meadow restoration was changed in accordance with experts’ recommendations. Thus stable or increasing numbers of Locustella fluviatilis can be explained with the fact that the area restored with shrubs cutting are smaller than initially planned.
The yearly maximum of Crex crex and Locustella naevia recoded in Rakupe meadows in 2008 were the highest since counting of these species in the territory was started. The most part of this territory underwent restoration activities until the breeding seasons of 2006 or 2007. As a result increase in numbers of Crex crex and Locustella naevia most likely is associated with continued management after initial mowing and shrubs cutting activities. After a peak in numbers in 2007, a drop in numbers of Locustella fluviatilis was recorded in 2008. It is believable that this change isn’t associated with the restoration activities carried out by the project, but represent changes in breeding population of Latvia.
Lake Durbe meadows.
In this territory numbers of Locustella naevia continue to decrease and in 2008 reached their lowest numbers since project counting was started. Although in 2008 a drop in numbers of Crex crex was recorded, there was only negligible difference if compared with 2007. Gallinago gallinago and Locustella fluviatilis were recorded in higher numbers in 2008 than it was in the previous year, but these changes weren’t prominent due to fact that in all years during project these species were counted in small numbers. Because most of planed restoration activities took place in this territory, it is believable that changes in counted numbers of target and indicator species are associated with conditions in adjacent agricultural lands outside this project territory.
After a peak in numbers in 2007, a drop in numbers of Crex crex, Locustella fluviatilis and Locustella naevia was recorded in 2008. Lower number of calling Crex crex may be explained with late restoration activities in the north and north-eastern part of the site. Shrub removal in these areas was finished shortly before breeding season. Consequently, delayed revegetation caused lower density of Crex crex in this part of territory.
Except for slight drop in comparison with 2007, numbers of Crex crex in 2008 are still higher than in 2005 and 2006. Because most part of this territory underwent restoration activities until the breeding season of 2007, increases in recorded numbers of Crex crex most likely is a result of increased open meadow areas due to the management activities carried out by the project.