Andy Adcock
Worst person on Birdforum
Not a single bird, singing or displaying on my patch in Russia.
Anyone else down on numbers?
A
Anyone else down on numbers?
A
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Tree Pipit absence (1 Viewer)
- Thread starter Andy Adcock
- Start date
Richard Prior
Halfway up an Alp
Numbers seem to be normal in my neck of the Alps Andy.
Andy Adcock
Worst person on Birdforum
Hi Andy,
Checking ornitho.de, it seems last year there were several 10-day-periods with well more than 1500 observations logged, while this year, roughly the same periods peak just above 1000.
On the other hand, if I run a query for observations with codes for breeding status and ask for number of individuals, there doesn't seem to be a big difference to 2017.
It might be that there was a difference in the number of migratory Tree Pipits in Germany, or that there was a difference in observation intensity ... ornitho.de is a collection of random observations, after all.
Regards,
Henning
Checking ornitho.de, it seems last year there were several 10-day-periods with well more than 1500 observations logged, while this year, roughly the same periods peak just above 1000.
On the other hand, if I run a query for observations with codes for breeding status and ask for number of individuals, there doesn't seem to be a big difference to 2017.
It might be that there was a difference in the number of migratory Tree Pipits in Germany, or that there was a difference in observation intensity ... ornitho.de is a collection of random observations, after all.
Regards,
Henning
Nutcracker
Stop Brexit!
They've disappeared from a number of sites in Northumbs in the last few years, but holding on well in others. Seems to be habitat-related: those on moorland fringe and upland broadleaf woods have gone, those on conifer plantation clear-fells are doing OK. Probably related to agrochemical inputs (sheep dosed up with ivermectin and other worming stuff means sterile dung and no insects; conversely no sprays used in forestry).
Hi,
The "Atlas of German Breeding Birds", 2014 edition, notes that the German Tree Pipit population shows a negative trend both long term and short term. Since the beginning of the systematic monitoring program in 1990, population numbers have halved.
The root causes aren't firmly established, but probably include negative changes both along the migration route and in the wintering areas, intensification of farming in Germany, a change in foresting practices eliminating clear-fells, and anthropogenic immissions changing woodland ecology and contributing to the ongoing loss of habitats.
Regards,
Henning
The "Atlas of German Breeding Birds", 2014 edition, notes that the German Tree Pipit population shows a negative trend both long term and short term. Since the beginning of the systematic monitoring program in 1990, population numbers have halved.
The root causes aren't firmly established, but probably include negative changes both along the migration route and in the wintering areas, intensification of farming in Germany, a change in foresting practices eliminating clear-fells, and anthropogenic immissions changing woodland ecology and contributing to the ongoing loss of habitats.
Regards,
Henning
Andy Adcock
Worst person on Birdforum
this describes my habitat yet noting has changed for decades here, very little agriculture.
A
Andy Adcock
Worst person on Birdforum
We're talking a total absence here this year.
Chiffchaff and Wood Warbler seem to be down too and for the first time in five years, I haven't found breeding Rb Shrikes.
A
Hi Gordon,
You can probably diregard the fact that the percentages are small, as they are based on observation lists. It's quite likely that many of these observation lists cover habitats that are not of interest for Tree Pipits, so it might be perfectly normal that more than 95% of the lists don't show Tree Pipits at all.
Assuming that the number of observation lists is sufficiently large, and the observations distributed reasonably evenly both in space and in time (in particular, with no systematic difference between years), you can derive the relative frequency of Tree Pipits at any time from the percentage values, even if you don't have any absolute numbers.
Regards,
Henning
You can probably diregard the fact that the percentages are small, as they are based on observation lists. It's quite likely that many of these observation lists cover habitats that are not of interest for Tree Pipits, so it might be perfectly normal that more than 95% of the lists don't show Tree Pipits at all.
Assuming that the number of observation lists is sufficiently large, and the observations distributed reasonably evenly both in space and in time (in particular, with no systematic difference between years), you can derive the relative frequency of Tree Pipits at any time from the percentage values, even if you don't have any absolute numbers.
Regards,
Henning
Hi H - that's what I mean. For instance, it's unclear what each submitted complete list covers. It depends how the observer has defined the site for which the list is submitted - ie, what scale? 1k squ or 10k squ ? Therefore what proportion of each list comprises habitat for a particular species?
I agree that it may provide a rough general overview but it's only that and needs to be approached with caution. As an example, all of "my" Swifts arrived on exactly the same date as the past 6 years it seems many, even much further south, were much later. And, numbers arriving varied enormously too.
I think it is still a helpful tool though.
Cheers
Gordon
Hi Gordon,
Thanks, that looks like a good description of what's going on behind the scenes!
Ornitho.de offers a function to get from number of observations to number of individuals, which would appear like a slightly more useful variant. However, the report doesn't tell one how the number is arrived at, so I can't really assess its limitations.
Regards,
Henning
Thanks, that looks like a good description of what's going on behind the scenes!
Ornitho.de offers a function to get from number of observations to number of individuals, which would appear like a slightly more useful variant. However, the report doesn't tell one how the number is arrived at, so I can't really assess its limitations.
Regards,
Henning
Brosnabirder
Well-known member
I can't tell you anything about birdtrack and ebird but ornitho.de and other websites in the group generally work on a scale of 1 square kilometre. There are some special sites which are within a particular kilometre square or overlap squares but most are very small sites such as ponds etc. Other sites larger than 1 square kilometre such as lakes etc are generally used for wildfowl counts in winter. It's also possible to report a sighting for an exact point within a kilometre square. This is especially useful for anything from Dipper nest sites to rarity reports. Personally I mostly use the app for ornitho.ch in Switzerland which allows me to give an exact location for a sighting using GPS. The system rather than the observer defines the extent of the site.
For all species you can generate a list of sightings for a particular date or time frame as a list or in the form of a map with all reports plotted on it including the numbers of the species. Especially useful for comparison of numbers across years. Of course there are limitations in terms of differences in observer effort across years or seasons and there's little publicly available information on habitat use within a particular square kilometre but it mostly relies on volunteers in the end.
All the best
Tom
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Hi Tom,
That's actually something I always wanted to know!
It doesn't seem to be documented anywhere on their site, so your comment inspired me to take a closer look at the grid ...
Turns out your 1 km^2 estimate is pretty accurate despite ornitho.de being based on a latitude/longitude grid, not on a distance grid: ornitho.de appears to use the Topologische Karte 1:25000, which is traditionally published on numbered charts of 6' of latitude, 10' of longitude.
If my count is correct, for any numbered chart sheet, there are 12 squares in ornitho.de latitudinally and 10 longitudinally, so a single square would cover 30" latitude, 1' longitude. That would make it about 0.9 km by 1.09 to 1.26 km (in Germany), depending on latitude.
(I wouldn't be surprised if other country-specific implementations of ornitho use a different grid system.)
Ornitho.de has one interesting chart that is semi-useful for assessing observation intensity ... it's the observer population map:
https://www.ornitho.de/index.php?m_id=1119&item=14
However, as birders don't necessarily watch their home patch most closely, but travel around a lot, a map showing observations per grid square would probably be more informative ...
Regards,
Henning
That's actually something I always wanted to know!
It doesn't seem to be documented anywhere on their site, so your comment inspired me to take a closer look at the grid ...Turns out your 1 km^2 estimate is pretty accurate despite ornitho.de being based on a latitude/longitude grid, not on a distance grid: ornitho.de appears to use the Topologische Karte 1:25000, which is traditionally published on numbered charts of 6' of latitude, 10' of longitude.
If my count is correct, for any numbered chart sheet, there are 12 squares in ornitho.de latitudinally and 10 longitudinally, so a single square would cover 30" latitude, 1' longitude. That would make it about 0.9 km by 1.09 to 1.26 km (in Germany), depending on latitude.
(I wouldn't be surprised if other country-specific implementations of ornitho use a different grid system.)
Ornitho.de has one interesting chart that is semi-useful for assessing observation intensity ... it's the observer population map:
https://www.ornitho.de/index.php?m_id=1119&item=14
However, as birders don't necessarily watch their home patch most closely, but travel around a lot, a map showing observations per grid square would probably be more informative ...
Regards,
Henning
Brosnabirder
Well-known member
Hi Tom,
That's actually something I always wanted to know!
Turns out your 1 km^2 estimate is pretty accurate despite ornitho.de being based on a latitude/longitude grid, not on a distance grid: ornitho.de appears to use the Topologische Karte 1:25000, which is traditionally published on numbered charts of 6' of latitude, 10' of longitude.
If my count is correct, for any numbered chart sheet, there are 12 squares in ornitho.de latitudinally and 10 longitudinally, so a single square would cover 30" latitude, 1' longitude. That would make it about 0.9 km by 1.09 to 1.26 km (in Germany), depending on latitude.
(I wouldn't be surprised if other country-specific implementations of ornitho use a different grid system.)
Ornitho.de has one interesting chart that is semi-useful for assessing observation intensity ... it's the observer population map:
https://www.ornitho.de/index.php?m_id=1119&item=14
However, as birders don't necessarily watch their home patch most closely, but travel around a lot, a map showing observations per grid square would probably be more informative ...
Regards,
Henning
Hi Henning
I'm not sure if ornitho.de has this feature since I only use it occasionally but ornitho.ch allows the user to see the ranking order of different cantons based on the total number of sightings contributed for a particular year, month or overall. You can also see the same statistics for the parishes or communities within a particular canton. See the two attached screenshots. I don't think it's possible to see similar statistics for individual one km squares.
The list of cantons also includes some areas in the countries which border Switzerland. This is useful as Swiss birders regularly travel to neighbouring countries and is not some form of ornithological irredentism. ;-)
All the best
Tom
Attachments
James Eaton
Trent Valley Crew
Andy,
I was in Yakutsk early June, Tree Pipit was locally abundant, fortunately. It was really interesting seeing them only in big clearing more open habitats than I usually associate them with, as in the smaller clearings and forest they were directly replaced by Olive-backed Pipit.
James
Andy Adcock
Worst person on Birdforum
Thanks James,
that's a long way from us James, you were more than breadth of Ukraine, Mongolia and Kazakhstan away from us and they're not small countries!
I can never get used to seeing Fieldfares and Redwings all summer.
A
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