Growing roe deer population impacting birds in UK? (1 Viewer)

[Nightranger]

The 'nomadic' or 'roaming' thing you all mention, visiting smaller fragments, is probably just the home ranges expanding to those massive sizes from the breeding core areas. The birds aren't 'roaming' (with no fixed base), insomuch as they're expanding their home ranges from the core to cover those several hundred hectares.

So a highly fragmented landscape logically makes this even harder, as the birds have to link together more bits of woodland, putting them at more risk by trabelling further distances between smaller fragments. A 100 ha block is clearly better than 10 x 10 ha blocks for a woodland specialist.

I am still following this thread with interest although a family crisis means my thoughts are for the most part elsewhere at the moment. However what I would note here to tie everything you have said and what Jos and Locustella are discussing is not to get too tied up on the idea of woodland requirements for LSW in winter. Like a lot of insectivorous birds, they can be forced away from preferred habitats in winter. Indeed, it probably surprises a lot of people that LSWs will feed on the ground in a fashion more like green woodpeckers in winter. This means they can be seen in unlikely locations such as arable fields (particularly in the days of set-aside). It is true enough to say that LSWs will become more vulnerable to predation at certain times of the year through their behaviour too but an equally high cause of mortality could easily be lack of food, particularly in a cold spring. I realise this is not completely applicable to the idea of minimum habitat requirements but it is important in understanding the behaviour of LSWs at different times of the year.

 

[dantheman]

Presumably the decline of the LSW's is due to them being trampled by the increasing numbers of Roe Deer ... ?

 

[AlfArbuthnot]

I don't think the Swedish study (abstract) highlighted any requirement for single forest blocks in excess of 100 ha in winter.

Nobody said it did, or that 100 ha was a magic number. It was a yardstick, that's all. I wouldn't get hung up on it.

 

[Jos Stratford]

Nobody said it did, or that 100 ha was a magic number. It was a yardstick, that's all. I wouldn't get hung up on it.

A little earlier, you argued that the rarity of patches of woodland 100 ha in size was important because 'we know that 100 ha is towards the minimum home-range size of Lesser Spotted Woodpecker'. As illustrated, knowing that 100 ha is 'towards the minimum home-range size' is not necassarily indicative of the importance of 100 ha patches of forest at all.

I am not hung up on it, fortunatley the Lesser Spotted Woodpeckers don't seem to be either - I know plenty of pairs breeding successfully in fragmented woodland.

 

[AlfArbuthnot]

I am not hung up on it, fortunatley the Lesser Spotted Woodpeckers don't seem to be either - I know plenty of pairs breeding successfully in fragmented woodland.

They seem quite hung up on fragmentation in England and Wales, where a quick google gives the following,

the catastrophic decline has been concentrated in areas of least habitat and most fragmented cover,
"the spatial study therefore provides support for the assumption that the large territories recorded in Sweden (Wiktander et al., 2001) can be used to contextualise British studies of Lesser Spotted Woodpeckers."
http://www.sciencedirect.com/science/article/pii/S1574954112001227

And also this study "There was a strong relationship between wood use probability and the extent of woodland within a 3-km radius, suggesting selection for more heavily wooded landscapes." http://onlinelibrary.wiley.com/doi/10.1111/j.1474-919X.2010.01020.x/abstract

This for a species that has a home range that only dips below 100 ha when nesting, "Home-range size did not vary between age-groups or sexes, but varied with season and decreased successively from 742 ha in winter (n=10), 355 ha in early spring (n=15), 103 ha in late spring (n=22) to 43 ha during nesting (n=10)." http://www.sciencedirect.com/science/article/pii/S0006320701000453

So it seems that a 100 ha block of woodland really would be better for them than 10 fragmented blocks of 10 ha each, in the English context which is the subject of this discussion.

They might breed successfully in small woods in Eastern Europe, but that doesn't tell you anything about how they survive for the rest of the year in England.

 

[Nightranger]

They seem quite hung up on fragmentation in England and Wales, where a quick google gives the following,

Alf, a note of caution repeating something you fired back at me...a quick Google search means nothing...there is a lot of scientific research that has not been published or abstracted online and it is wrong to assume that everything is covered in reverse lit' references. I spotted your debating technique in this respect long ago but I let it go because I recognised you as a genuine person who makes us all think. I wondered why you pulled me up about accepted facts in behaviour and ecology but then I realised you were using online resources almost exclusively. I am sure you have seen genuine ink and paper publications in the past but I am unsure why you can ignore these sources and rely on contemporary studies that have not stood the test of time.

 

[Jos Stratford]

They seem quite hung up on fragmentation in England and Wales, where a quick google gives the following,

"the spatial study therefore provides support for the assumption that the large territories recorded in Sweden (Wiktander et al., 2001) can be used to contextualise British studies of Lesser Spotted Woodpeckers."
http://www.sciencedirect.com/science/article/pii/S1574954112001227

And also this study "There was a strong relationship between wood use probability and the extent of woodland within a 3-km radius, suggesting selection for more heavily wooded landscapes." http://onlinelibrary.wiley.com/doi/10.1111/j.1474-919X.2010.01020.x/abstract

This for a species that has a home range that only dips below 100 ha when nesting, "Home-range size did not vary between age-groups or sexes, but varied with season and decreased successively from 742 ha in winter (n=10), 355 ha in early spring (n=15), 103 ha in late spring (n=22) to 43 ha during nesting (n=10)." http://www.sciencedirect.com/science/article/pii/S0006320701000453

So it seems that a 100 ha block of woodland really would be better for them than 10 fragmented blocks of 10 ha each, in the English context which is the subject of this discussion.

They might breed successfully in small woods in Eastern Europe, but that doesn't tell you anything about how they survive for the rest of the year in England.

Your first example refers to the Swedish study that talks about large territories, not large forest blocks.

Your third example is again the same Swedish study, still not referring to 100 ha blocks.

As you wish to dismiss the observations of both Locustella and myself as being in Eastern Europe and 'telling nothing' about England, it is interesting that the main source you use to support your view is Sweden, a study that does not say what you say anyhow and is of a very small number of birds in a very small area.

 

[AlfArbuthnot]

Your first example refers to the Swedish study that talks about large territories, not large forest blocks.

Your third example is again the same Swedish study, still not referring to 100 ha blocks.

As you wish to dismiss the observations of both Locustella and myself as being in Eastern Europe and 'telling nothing' about England, it is interesting that the main source you use to support your view is Sweden, a study that does not say what you say anyhow and is of a very small number of birds in a very small area.

Try reading them. Study 1 and 2 are British, and agree that study 3 (Swedish) is valid for Britain. Study 1 and 2 both find that fragmentation is very bad for Lesser Spots, and that when it comes to woodland then more is better (i.e. larger blocks, rather than smaller blocks).

Here's another study showing that the likelihood of Lesser Spots being in a woodland decreases with the isolation and AREA of the woodland block in the Netherlands.
http://www.sciencedirect.com/science/article/pii/0006320785900394

As I said, 100 ha is not a magic number for Lesser Spots, but just a contrast of a woodland species with very large territories versus the rarity of large blocks of woodland habitat (i.e. potential territories) in England. You could pick any other species with large home-ranges if you wish, or another 'big' woodland size, to make the point about there probably being too little woodland for a viable population of Lynx in England.

 

[Wildmoreway]

Some of the people responding here are forgetting another important point about the UK in that it is an island separated from mainland Europe by a minimum of about 30 kilometres of water and many species simply cannot or do not cross that barrier leading to the situation where populations here have become more and more isolated as the wildwood cover has been fragmented. In addition there is the problem that even when things are improved there is a lack of natural movement of many species from mainland europe to repopulate suitable areas.

For many people in the UK the word "acre" has got more meaning than "ha", 100 ha translates to about 247 acres, a land area that I can easily visualise, and unfragmented woods of 247 acres or more in the UK are very rare indeed and even within most of our UK "forests" such as the New Forest etc truly unfragmented woods of that size or more may well not exist.

There is also the issue in the UK that there often barriers to movement of some wildlife that do not exist in in mainland Europe. In the UK railways are fenced and enclosed whereas in most of mainland Europe they are normally unfenced and in some cases the same applies to motorways. (I do understand from a posting by Jos elsewhere that in his part of the world the bridges over motorways themselves lack parapets and large numbers of cyclists fall from the said bridges).

 

[Jos Stratford]

Try reading them.

Arrogance will get you everywhere. I have read them. Study one and the Swedish study both refer to habitat density, the more habitat the better, that we can both agree. Neither study, nor the third, specifically mentions required sizes of forest blocks. Fragmented forest, if connected or close together, could equally well apply in all these studies.

I believe you introduced the 100 ha forest blocks statement into the discussion, linking it with the comment that such blocks were of importance because 'we know that 100 ha is towards the minimum home-range size of Lesser Spotted Woodpecker'.

This data you acquired from a study in Sweden, yet when examples were provide from myself and Locustella where Lesser Spotted Woodpeckers can occur in much smaller blocks of high quality habitat, you could do no better than dismiss it by trying to cast it aside saying Eastern Europe tells nothing about England.

Sweden to Lithuania is about 300 km, Sweden to the UK is about 800 km. Information from Sweden is okay for you, information from Lithuania and Poland says nothing according to you.

 

[dantheman]

Nobody said it did, or that 100 ha was a magic number. It was a yardstick, that's all.

Shouldn't that be a metrestick?

 

[Jos Stratford]

... in most of mainland Europe they are normally unfenced and in some cases the same applies to motorways. (I do understand from a posting by Jos elsewhere that in his part of the world the bridges over motorways themselves lack parapets and large numbers of cyclists fall from the said bridges).

Despite your sarcasm, or your unfortunate misunderstanding, if the effects of fencing or not fencing are of interest to you, I could quote the per kilometre mortality rate of mammals on all the major highways and country roads in this country, including those fenced and those not. Plus studies that consider the impact of roads as barriers to movements amongst mammal species, including deer and lynx.

 

[AlfArbuthnot]

Fragmented forest, if connected or close together, could equally well apply in all these studies.

No! Because if there are small blocks versus a large block, then habitat is at a lower density for the small blocks, due to the gaps. A 100 ha block of woodland contains 100 ha of trees in 100 ha of land. 10 x 10 ha of woodland contains 100 ha of woodland but in MORE than 100 ha of land, because of the gaps, so density of woodland (tree coverage per 100 ha) is lower.

Both British studies show that Lesser Spots prefer high density habitat. For the third time, 100 ha is not a magic number and was never said as such, it was just a convenient unit used in the Forestry Inventory to make the point that large blocks of woodland are rare in England. Lesser Spot was used as an exmaple of a species where large blocks of woodland are a limiting factor. This is PROVEN by the first study, which found that the decline was concentrated in area of greater frargmentation, and furthermore that Lesser Spots had never occupied woodland that was the most fragmented. Fragmentation is a function of block size and isolation.

Information from Sweden is okay for you, information from Lithuania and Poland says nothing according to you.

I'd love examples from Lithuania and Poland. Sadly, what you and Lucustella gave me was personal memories of birds you have seen somewhere at some point. To my mind, that hardly seems to compare to 4 science papers including radiotracking, regional and national studies by professional scientists using data spanning 20 years.

That's all from me.

 

[AlfArbuthnot]

Shouldn't that be a metrestick?

Well done! But they're ever so slightly longer.

 

[Jos Stratford]

This is PROVEN by the first study...

The study did not prove anything, it provides a theory to account for a reduction in the species, albeit a good theory. This is not the same as proving it and I do not think the authors concerned would claim it proves anything (cetainly not in capital letters). Unknown factors could potentially be involved.

Anyhow, they talk about percentage cover, not block size. Fragmented forests, as was actually the case in the Swedish woodpecker pairs, can still exist at sufficient densities to maintain Lesser Spot populations.

I'd love examples from Lithuania and Poland. Sadly, what you and Lucustella gave me was personal memories of birds you have seen somewhere at some point. To my mind, that hardly seems to compare to 4 science papers including radiotracking, regional and national studies by professional scientists using data spanning 20 years.

Both Locustella and I live in areas where Lesser Spots are fairly common. What we actually gave you were personal accounts based on considerable experience with the species, the fact that you wish to dismiss it is a reflection on you, not our observations.

You have posted a number of inaccuracies regarding this species in your posts and, it would seem, are basing everything on what you can find via google. The fact remains that Lesser Spotted Woodpeckers can and do frequently maintain populations in small woodland patches. This is not at all at odds with the findings of the papers you quote, they talk of woodland density and connectivity of plots - neither of which exclude small plots. Even if it were at odds with the findings however, it is still relevant as it would be a mistake to believe that management of woodlands for this species always requires large single plots. It doesn't ...if you don't wish to acknowledge this, so be it. We will have to agree to disagree.

 

[locustella]

Sadly, what you and Lucustella gave me was personal memories of birds you have seen somewhere at some point. To my mind, that hardly seems to compare to 4 science papers including radiotracking, regional and national studies by professional scientists using data spanning 20 years.

Lesser spotted woodpecker in that particular 50 ha alder forest was very easy to notice in the absence of leaves, at least in November and February (I have few observations in the past written down, but that is not everything at all !), especially during winter when ground was frost, because that is very wet, almost inaccessible inside and hidden by very dense vegetation - almost nothing is visible during Summer. This bird is very easy to recognize, even without binoculars because of short escape distance. Don't remember today if I saw it during breeding season. There is also publicatin listing it as wintering species in that forest in such journal entitled Kulon [Eurasian Stone-curlew]. But it doesn't mean, that it was nesting species there. Currently in that forest Great Spotted Woodpecker Dendrocopos major (very common species everywhere), Black Woodpecker Dryocopus martius and rarely European Green Woodpecker Picus viridis. All three are wintering, the black Woodpecker voice is audible also in Spring and Summer, Great Spotted Woodpecker is probably nesting species too because it is easy to notice in Spring. During Summer everything is hidden in very dense vegetation, swamps, birds are silent and there are mosquitos everywhere.

100 ha

Thats good for birds, 100 ha is better than 50 ha - more birds would like such place.

Just found information in such ornithological book - Lesser Spotted Woodpecker lives in middleaged and old deciduous forests, especialy likes forests adjanced to rivers (along them) and wet swampy alderforests, rarely nests in cityparks larger than 20-30 ha or woodlots among fields.

 

[Wildmoreway]

It would be interesting to know if any investigation has been made into the effects of human made trackways (capable of taking vehicles) and of metalled roads through some of the 100 ha + woodlands. In the areas that I am familiar with there does seem to be very limited movement of wildlife across such places. In the case of small mammals crossing such trackways it is very risky as they are vulnerable to predators, indeed many birds seem to also be reluctant to cross such places even if they are no more than a few metres wide. I do suspect that in many cases the presences of these trackways does have a fragmentary effect and means that for some species these woodlands are no more viable as a habitat than are smaller more widely separated woodlands.

It is worth looking at the remnants of some of the former highways prior to the turnpike era, and it is quite surprising to some people when you show them that such roads were no more than two metres wide for much of their distance and that when they passed through woodlands they were often completely overhung by the tree canopy, and their effect on the movement of wildlife must have been much less than that of of modern "farmland" type trackways.

 

[Jos Stratford]

It would be interesting to know if any investigation has been made into the effects of human made trackways (capable of taking vehicles) and of metalled roads through some of the 100 ha + woodlands.

There have been studies into this topic here in Lithuania, the results I believe now published in journals. Whilst they were not specifically considering the division of woodlands as such, they were looking at roads both in terms of mortality and its possible impact on overall populations, as well as considering the roads as forms of barriers to animal movement, the results analysed for both fenced and unfenced roads.

 

[Jos Stratford]

In the areas that I am familiar with there does seem to be very limited movement of wildlife across such places. In the case of small mammals crossing such trackways it is very risky as they are vulnerable to predators, indeed many birds seem to also be reluctant to cross such places even if they are no more than a few metres wide.

Somebody else will know the details better than me, but an example from the UK that surprised me recently was when I heard about 'bat bridges' being built over some major road in the south of England. I am hazy on the details, but I think the idea was a relatively wide bridge, not open to vehicles, but well-planted. I initially thought they were joking, but this particular bat species (sorry don't remember which one) very much sticks to flight lines above hedgerows etc and the wide expanse of the motorway was effectively a barrier to even this winged species.

 

[MJB]

It would be interesting to know if any investigation has been made into the effects of human made trackways (capable of taking vehicles) and of metalled roads through some of the 100 ha + woodlands.

The Dutch have done a lot of work on the consequences of fragmented woodland, and so perhaps some of our Dutch BF members might comment?

The Netherlands is one of the few western European countries to have actively pursued woodland expansion that is not limited to monocultures, about 17-19% of the total area, I believe, although that figure has been dredged from my memory of the 1990s. Is there a deer population 'problem' in the Netherlands?
MJB