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Birds of Danish SPA's

Discussion 

Trends for breeding Appendix I species

In 1983, 15 breeding Appendix I species formed part of the rationale for the designation of the majority of the SPAs. As some species have since been added to Appendix I and some additional species have started to breed within the areas the total number of Appendix I species which have bred within Danish SPAs since designation is 35.

Many Appendix I species occur in more SPAs than originally designated for them

Table 1 shows for all Appendix 1 species found breeding in SPAs the number of areas where the species was part of the original reasons for designation and the total number of SPAs where the species have bred 1979-1999. Most species can be seen to have bred in more SPAs than were originally designated for them. In some cases, the "extras" are just sites of occasional breeding which were considered at time of designation to be without importance for the future status of the Danish population. For other species, though, the "extras" are sites of importance for the Danish populations of the respective species.

The high number of "extras" for some species reflects real increase and spread of the Danish population (e.g. Botaurus stellaris, Circus aeruginosus, Haliaetus albicilla and Dryocopus martius) for others probably just better knowledge (e.g. Pernis apivorus).

Several of the 35 species were not originally mentioned as the reason for designation of any SPAs (i.e. have a zero in the first column). Some of these species have only very recently (re-) colonized Denmark (Platalea leucorodia, Branta leucopsis, Haliaetus albicilla, Bubo bubo and Luscinia svecica) while many others (e.g. Tetrao tetrix, Philomachus pugnax and Lanius collurio) have been added to Appendix 1 after the designation of the SPAs.

The two last columns show that for all gregariously breeding species more than half (in most cases substantially more, see species accounts) of the Danish breeding populations are covered by the SPA network. For species which are dispersed while breeding the coverage is high only for very rare species.

Differences in trends for breeding Appendix 1 species inside and outside SPAs

Table 2 summarises the general trends in abundance for the 35 species both inside and outside the SPAs since the designation of the SPAs. The trends are just given as increasing, stable or decreasing. In some instances, this means that differences in trends are discounted as species with the "same" trend – either increasing or decreasing – both inside SPAs and in other parts of their Danish range might have a higher rate of change inside than outside the areas or vice versa.

In the first column are three groups of species doing better inside than outside the SPAs.

The first group – species increasing in SPAs and decreasing elsewhere – is comprised of only one species namely Tringa glareola. The Danish population of this species have stabilized or possibly slightly recovered, this being a result of improved management of key localities (all SPAs) while the species has mostly disappeared from the scattered secondary localities outside the SPA network.

The second group – species that have increased within SPAs while remaining stable outside – comprises seven species. Five of these species have recently re-colonized – Platalea leucorodia, Haliaetus albicilla, Circus cyaneus and Luscinia svecica – or colonized – Branta leucopsis – Denmark and all pairs breed in or in close connection to SPAs so the "stable" population outside is actually zero. Two species – Sterna paradisaea and Recurvirostra avosetta – have increasing Danish populations, but nearly all the increase has occurred in the main colonies which all are SPAs while the smaller colonies outside SPAs are mostly fluctuating.

The third group – stable inside SPAs and decreasing outside – consists of two species – Philomachus pugnax and Sterna albifrons. Both species have stabilized and partly recovered as result of improved management of a few key sites (all SPAs) but continues to decrease elsewhere both inside and outside the SPA network.

The second column consists of three groups with similar trends inside and outside the SPAs.

The first group in the second column – species that have increased both inside and outside SPAs – comprises seven species. Three species – Milvus milvus, Grus grus and Bubo bubo – are formerly exterminated species currently under re-colonization and an additional one Circus aeruginosus is still recovering from formerly intense persecution. Dryocopus martius has colonized Denmark, probably as a result of planting of conifers and is still expanding its range. Alcedo atthis fluctuates markedly as a result of increased mortality in cold winters, but is presently at the highest level recorded yet. The last species in this group is Botaurus stellaris, which for reasons that are not fully known is staging a major recovery.

The second group consists of species that have been fluctuating or roughly stable both inside and outside the SPAs. Eight species have been placed in this group. Several of these, though, might conceivably belong elsewhere e.g. Caprimulgus europaeus might actually be decreasing both inside and outside SPAs.

The third group – species that have decreased inside as well as outside the SPAs – consists of seven species. One species – Tetrao tetrix – is almost certainly now extinct in Denmark and another three – Ciconia ciconia, Crex crex and Sylvia nisoria - are close to extinction. Anthus campestris is now considered endangered in Denmark. So is Chlidonias niger which has decreased markedly and the breeding success - even at the core sites - for the species has been very low in recent years. Asio flammeus is highly fluctuating in relation to rodent densities and might actually belong in the 0/0 category.

The last column includes three groups - each consisting of only one species – for which the trend is more positive outside than inside the areas.

The only species here regarded as stable inside and increasing outside SPAs is Sterna hirundo. The species fluctuates markedly and the comparison is thus influenced by the exact choice of start and endpoint of analysis period. The apparent increase outside SPAs might also reflect increased coverage during the BirdLife Denmark Atlas project 1993-96.

The only species classified as decreasing within SPAs and stable outside is Gelochelidon nilotica. The decreasing Danish population of this species has in the whole period 1983-1999 been limited to SPAs so the "stable" population outside the areas is zero.

Only one species is decreasing inside SPAs and increasing outside: Circus pygargus. The recent, unexplained shift in breeding habitat of parts of the otherwise apparently stable population from heathland bogs to agricultural fields has resulted in a decreased SPA coverage for the species.

In summary 10 species are doing better inside SPAs than outside, for 22 species the trends inside and outside the areas are approximately the same and 3 species actually show better trends outside the SPAs.

Looking at it in another way the table also shows that of the 35 species 15 have increased 11 have been stable and 9 have decreased within the SPAs since the designation of the areas.

Trends for staging birds

Table 3 shows (for all non-Appendix 1 species occurring in internationally important numbers in the SPAs) the number of areas where the species was part of the original reason for designation and the total number of SPAs where the species fulfilled the 1% criterion 1979-1998. Most species have occurred in such numbers in more SPAs than those, which were originally designated for them. In some instances, the opposite is true, though – i.e. species formed part of the reason for designation for more areas than where they have actually occurred in numbers fulfilling the 1% criterion. This is in most cases not caused by occurrence of lower numbers, but is due to the fact that estimates of total flyway populations have been revised to higher levels.

As numbers of staging birds at most sites are only counted yearly the trends for staging birds are less well known than for the breeding Appendix I species. Despite some reserves being monitored much more closely, the – in general – infrequent counts for many species results in random fluctuations obscuring eventual trends. In the material compiled here - see table 4 -overall increases and decreases are only evident for 5 and 3 species respectively. For all 5 species, which show increasing staging numbers, the birds utilising Danish staging areas come from populations which are increasing overall. The reverse is also true: two of the three species decreasing in staging numbers the Danish staging birds belong to populations in overall decline. The Danish wintering numbers of the last species Fulica atra dropped 1978-94 (Asbirk et al 1997). At some sites, this was probably the result of eutrophication damaging macrophytes, but the trend for the species is also heavily influenced by high mortality in cold winters. The decline could also be linked to a decrease in breeding numbers observed in Sweden and Finland (Snow and Perrins 1998).

Table 1. The table shows for all Appendix 1 species breeding in the DSPAs the number of SPAs which were originally designated for them, the total number of SPAs where the species have bred since designation. Coverage is the fraction of the total Danish population occurring within SPAs.

¹ Actual nestsites are outside SPAs but relies heavily on SPAs for foraging

² The species is now considered extinct in Denmark

Table 2. Trends for Danish populations of breeding Appendix 1 species. For all species, the sign before the slash is trend inside SPAs, after the slash is trend in Denmark outside the SPAs. + = Population of species has increased since designation of SPAs, 0 = population roughly stable since designation and - = population has decreased since designation.

Table 3. The table shows for all non-breeding birds (both Appendix 1 and other migrant birds) in the DSPAs the number of SPAs which were originally designated for them and the total number of SPAs where the species has occurred in internationally important numbers. Coverage is the fraction of the total Danish population occurring within SPAs.

¹ breeding

Table 4. The table shows trends for staging birds in the DSPAs. The species in the + column now occur in higher numbers than at designation time, the numbers of the species in the 0 column have been roughly stable since designation and the species in the – column in later years have occurred in lower numbers than at designation time.

Trends for breeding Appendix I species
In 1983, 15 breeding Appendix I species formed part of the rationale for the designation of the majority of the SPAs. As some species have since been added to Appendix I and some additional species have started to breed within the areas the total number of Appendix I species which have bred within Danish SPAs since designation is 35.

Many Appendix I species occur in more SPAs than originally designated for them

Table 1 shows for all Appendix 1 species found breeding in SPAs the number of areas where the species was part of the original reasons for designation and the total number of SPAs where the species have bred 1979-1999. Most species can be seen to have bred in more SPAs than were originally designated for them. In some cases, the "extras" are just sites of occasional breeding which were considered at time of designation to be without importance for the future status of the Danish population. For other species, though, the "extras" are sites of importance for the Danish populations of the respective species.

The high number of "extras" for some species reflects real increase and spread of the Danish population (e.g. Botaurus stellaris, Circus aeruginosus, Haliaetus albicilla and Dryocopus martius) for others probably just better knowledge (e.g. Pernis apivorus).

Several of the 35 species were not originally mentioned as the reason for designation of any SPAs (i.e. have a zero in the first column). Some of these species have only very recently (re-) colonized Denmark (Platalea leucorodia, Branta leucopsis, Haliaetus albicilla, Bubo bubo and Luscinia svecica) while many others (e.g. Tetrao tetrix, Philomachus pugnax and Lanius collurio) have been added to Appendix 1 after the designation of the SPAs.

The two last columns show that for all gregariously breeding species more than half (in most cases substantially more, see species accounts) of the Danish breeding populations are covered by the SPA network. For species which are dispersed while breeding the coverage is high only for very rare species.

Differences in trends for breeding Appendix 1 species inside and outside SPAs
Table 2 summarises the general trends in abundance for the 35 species both inside and outside the SPAs since the designation of the SPAs. The trends are just given as increasing, stable or decreasing. In some instances, this means that differences in trends are discounted as species with the "same" trend – either increasing or decreasing – both inside SPAs and in other parts of their Danish range might have a higher rate of change inside than outside the areas or vice versa.

In the first column are three groups of species doing better inside than outside the SPAs.

The first group – species increasing in SPAs and decreasing elsewhere – is comprised of only one species namely Tringa glareola. The Danish population of this species have stabilized or possibly slightly recovered, this being a result of improved management of key localities (all SPAs) while the species has mostly disappeared from the scattered secondary localities outside the SPA network.

The second group – species that have increased within SPAs while remaining stable outside – comprises seven species. Five of these species have recently re-colonized – Platalea leucorodia, Haliaetus albicilla, Circus cyaneus and Luscinia svecica – or colonized – Branta leucopsis – Denmark and all pairs breed in or in close connection to SPAs so the "stable" population outside is actually zero. Two species – Sterna paradisaea and Recurvirostra avosetta – have increasing Danish populations, but nearly all the increase has occurred in the main colonies which all are SPAs while the smaller colonies outside SPAs are mostly fluctuating.

The third group – stable inside SPAs and decreasing outside – consists of two species – Philomachus pugnax and Sterna albifrons. Both species have stabilized and partly recovered as result of improved management of a few key sites (all SPAs) but continues to decrease elsewhere both inside and outside the SPA network.

The second column consists of three groups with similar trends inside and outside the SPAs.

The first group in the second column – species that have increased both inside and outside SPAs – comprises seven species. Three species – Milvus milvus, Grus grus and Bubo bubo – are formerly exterminated species currently under re-colonization and an additional one Circus aeruginosus is still recovering from formerly intense persecution. Dryocopus martius has colonized Denmark, probably as a result of planting of conifers and is still expanding its range. Alcedo atthis fluctuates markedly as a result of increased mortality in cold winters, but is presently at the highest level recorded yet. The last species in this group is Botaurus stellaris, which for reasons that are not fully known is staging a major recovery.

The second group consists of species that have been fluctuating or roughly stable both inside and outside the SPAs. Eight species have been placed in this group. Several of these, though, might conceivably belong elsewhere e.g. Caprimulgus europaeus might actually be decreasing both inside and outside SPAs.

The third group – species that have decreased inside as well as outside the SPAs – consists of seven species. One species – Tetrao tetrix – is almost certainly now extinct in Denmark and another three – Ciconia ciconia, Crex crex and Sylvia nisoria - are close to extinction. Anthus campestris is now considered endangered in Denmark. So is Chlidonias niger which has decreased markedly and the breeding success - even at the core sites - for the species has been very low in recent years. Asio flammeus is highly fluctuating in relation to rodent densities and might actually belong in the 0/0 category.

The last column includes three groups - each consisting of only one species – for which the trend is more positive outside than inside the areas.

The only species here regarded as stable inside and increasing outside SPAs is Sterna hirundo. The species fluctuates markedly and the comparison is thus influenced by the exact choice of start and endpoint of analysis period. The apparent increase outside SPAs might also reflect increased coverage during the BirdLife Denmark Atlas project 1993-96.

The only species classified as decreasing within SPAs and stable outside is Gelochelidon nilotica. The decreasing Danish population of this species has in the whole period 1983-1999 been limited to SPAs so the "stable" population outside the areas is zero.

Only one species is decreasing inside SPAs and increasing outside: Circus pygargus. The recent, unexplained shift in breeding habitat of parts of the otherwise apparently stable population from heathland bogs to agricultural fields has resulted in a decreased SPA coverage for the species.

In summary 10 species are doing better inside SPAs than outside, for 22 species the trends inside and outside the areas are approximately the same and 3 species actually show better trends outside the SPAs.

Looking at it in another way the table also shows that of the 35 species 15 have increased 11 have been stable and 9 have decreased within the SPAs since the designation of the areas.

Trends for staging birds
Table 3 shows (for all non-Appendix 1 species occurring in internationally important numbers in the SPAs) the number of areas where the species was part of the original reason for designation and the total number of SPAs where the species fulfilled the 1% criterion 1979-1998. Most species have occurred in such numbers in more SPAs than those, which were originally designated for them. In some instances, the opposite is true, though – i.e. species formed part of the reason for designation for more areas than where they have actually occurred in numbers fulfilling the 1% criterion. This is in most cases not caused by occurrence of lower numbers, but is due to the fact that estimates of total flyway populations have been revised to higher levels.

As numbers of staging birds at most sites are only counted yearly the trends for staging birds are less well known than for the breeding Appendix I species. Despite some reserves being monitored much more closely, the – in general – infrequent counts for many species results in random fluctuations obscuring eventual trends. In the material compiled here - see table 4 -overall increases and decreases are only evident for 5 and 3 species respectively. For all 5 species, which show increasing staging numbers, the birds utilising Danish staging areas come from populations which are increasing overall. The reverse is also true: two of the three species decreasing in staging numbers the Danish staging birds belong to populations in overall decline. The Danish wintering numbers of the last species Fulica atra dropped 1978-94 (Asbirk et al 1997). At some sites, this was probably the result of eutrophication damaging macrophytes, but the trend for the species is also heavily influenced by high mortality in cold winters. The decline could also be linked to a decrease in breeding numbers observed in Sweden and Finland (Snow and Perrins 1998).

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