Empathy List Archives

CE

Chris Elphick

Tue, Oct 4, 2011 12:17 PM

Paul,

A few responses to your question ... a bit long-winded I'm afraid ....

Before I start though, as a long-term advocate of breeding bird atlases, I have to second Jaime's comments. Most birding is pretty awful (sorry!) for assessing things like population size and trend because people tend to go to a limited number of sites; focus on really good sites (which gives a rosy impression of things); and if sites start to deteriorate, gradually shift to other locations, meaning that the birding stays good. Atlases are no panacea, but they at least get people into places that usually do not get birded and so provide a better sense of the big picture than does regular birding.

Turning more directly to your question, like many others I was very surprised by some of the projected population estimates in the State of the Birds. Before it was published, I was asked to review the article in question and suggested that those numbers should not be included without also providing two critical pieces of information - full details of the methods used to generate them and estimates of the uncertainty associated with them (i.e., the margin of error, or "confidence/credible intervals" to use the statistical terms). Both of these would be standard items in a formal scientific study. Because State of the Birds is not a scientific treatise, such details are generally not included in its articles. This is probably a good thing, as they clutter up the text and make it less accessible to anyone without statistical training. But these numbers struck me as sufficiently surprising that I felt the added information was necessary,
especially as there were no scientific journal articles to back them up.

Subsequently, I have heard (from the most reliable of authorities) that cerulean warblers are probably more numerous in CT than most birders think, at least in large forest blocks in the southeast portion of the state, and that numbers have increased in recent years (I'm not sure if the same is true for Acadians, but I don't think so). Even with that knowledge, though, I still find the estimates in the State of the Birds surprising and would not want to base conservation policy on them without some verification.

I still do not know the exact methods used to generate the numbers, but the general approach that is taken in situations like this is as follows:

Step 1. Sample the population using a standardized method at randomly selected locations. Point counts are the most commonly used method, but there are others. During these counts all birds seen and heard within a fixed time period (usually a few minutes) are recorded.

Step 2. Estimate how many individuals were missed at the sample points. This may sound strange, but there are a variety of mathematical methods available to do this - a very common one (though probably not a very good one for forest birds) involves estimating the distance to each bird detected during the count. I won't go into how you then use that information statistically, but would be happy to follow up with an explanation if anyone is interested. (Note that entire books, and dozens - probably hundreds - of scientific papers, have been written on these methods, which are also used for counting lots of things other than birds.)

Step 3. Extrapolate that information on bird numbers in the sampled areas (e.g., the point count locations) to the entire area of interest. This step will only work if the points truly were randomly located such that everywhere in the area of interest was equally likely to be visited. It also only works if you have good estimates of how much habitat there actually is.

So, that's the basic theory. It sounds simple, but in practice converting point counts to population estimates is fraught with difficulty (as one of the PhD students in my lab will attest!!). All of the different methods have assumptions and ensuring that those assumptions are met is often difficult. If they are not met then there are often ways to correct for them, but that requires more math and often increases the margin of error. Perhaps the biggest problem is that small errors at the first step can multiply (often hugely) as you work through the process - and especially if you end up extrapolating over large areas in step 3.

For forest birds, things are especially tricky. For example the methods that use distance estimates to determine how many birds were detected and how many were missed really depend on good estimates of those distances. Several studies, however, have shown that even highly trained observers are often terrible at estimating distances unless they actually see the bird. Most forest point counts rely on birds that are only heard, so this is a huge problem. These methods also run into problems if there is double counting, which is more likely if you have mobile animals (e.g., birds) especially those you can't see moving (e.g., because they're in the forest canopy). The standard way to deal with this is to keep the counts short, and even 5 minutes can be too long (in saltmarsh sparrows, double-counting starts to become a problem after ~4 minutes - and these birds are much easier to track than birds in a forest would be). Yet another problem is that
studies show that the more species you are tracking the more mistakes you make. Even going from 6 species to 8 species has been shown to create detectable increases in the errors. Forest bird point counts are often used to track dozens of species simultaneously.

All of this may sound as though it is impossible to use these methods in forests. That is not the case, but it is not simple and both field and analysis methods have to be chosen very carefully. In terms of the State of the Birds estimates, it is impossible to judge their accuracy without knowing exactly how the data were collected, how they were analysed, what assumptions were tested, etc. etc. If this is not done right then it would be very easy to produce extrapolations that are off by an order or magnitude.

Even if the basic estimates are good, the margins of error can be large so must be calculated so that one knows how much faith to put in an estimate. For example, I once did an analysis of this type and came up with a confidence interval that span six orders of magnitude (needless to say, I concluded that the estimate was pretty useless) - that was for a shorebird, where the tendency to form big flocks can really magnify the uncertainty, but it illustrates the problem.

So, for Roy and the two of you still reading (I'm an optimist I know) - sorry to tie up so much ctbirds space. Unfortunately, Paul's question is both very good and not at all easy to answer.

Chris

Chris Elphick

Storrs, CT

elphick@sbcglobal.net

Paul, A few responses to your question ... a bit long-winded I'm afraid .... Before I start though, as a long-term advocate of breeding bird atlases, I have to second Jaime's comments. Most birding is pretty awful (sorry!) for assessing things like population size and trend because people tend to go to a limited number of sites; focus on really good sites (which gives a rosy impression of things); and if sites start to deteriorate, gradually shift to other locations, meaning that the birding stays good. Atlases are no panacea, but they at least get people into places that usually do not get birded and so provide a better sense of the big picture than does regular birding. Turning more directly to your question, like many others I was very surprised by some of the projected population estimates in the State of the Birds. Before it was published, I was asked to review the article in question and suggested that those numbers should not be included without also providing two critical pieces of information - full details of the methods used to generate them and estimates of the uncertainty associated with them (i.e., the margin of error, or "confidence/credible intervals" to use the statistical terms). Both of these would be standard items in a formal scientific study. Because State of the Birds is not a scientific treatise, such details are generally not included in its articles. This is probably a good thing, as they clutter up the text and make it less accessible to anyone without statistical training. But these numbers struck me as sufficiently surprising that I felt the added information was necessary, especially as there were no scientific journal articles to back them up. Subsequently, I have heard (from the most reliable of authorities) that cerulean warblers are probably more numerous in CT than most birders think, at least in large forest blocks in the southeast portion of the state, and that numbers have increased in recent years (I'm not sure if the same is true for Acadians, but I don't think so). Even with that knowledge, though, I still find the estimates in the State of the Birds surprising and would not want to base conservation policy on them without some verification. I still do not know the exact methods used to generate the numbers, but the general approach that is taken in situations like this is as follows: Step 1. Sample the population using a standardized method at randomly selected locations. Point counts are the most commonly used method, but there are others. During these counts all birds seen and heard within a fixed time period (usually a few minutes) are recorded. Step 2. Estimate how many individuals were missed at the sample points. This may sound strange, but there are a variety of mathematical methods available to do this - a very common one (though probably not a very good one for forest birds) involves estimating the distance to each bird detected during the count. I won't go into how you then use that information statistically, but would be happy to follow up with an explanation if anyone is interested. (Note that entire books, and dozens - probably hundreds - of scientific papers, have been written on these methods, which are also used for counting lots of things other than birds.) Step 3. Extrapolate that information on bird numbers in the sampled areas (e.g., the point count locations) to the entire area of interest. This step will only work if the points truly were randomly located such that everywhere in the area of interest was equally likely to be visited. It also only works if you have good estimates of how much habitat there actually is. So, that's the basic theory. It sounds simple, but in practice converting point counts to population estimates is fraught with difficulty (as one of the PhD students in my lab will attest!!). All of the different methods have assumptions and ensuring that those assumptions are met is often difficult. If they are not met then there are often ways to correct for them, but that requires more math and often increases the margin of error. Perhaps the biggest problem is that small errors at the first step can multiply (often hugely) as you work through the process - and especially if you end up extrapolating over large areas in step 3. For forest birds, things are especially tricky. For example the methods that use distance estimates to determine how many birds were detected and how many were missed really depend on good estimates of those distances. Several studies, however, have shown that even highly trained observers are often terrible at estimating distances unless they actually see the bird. Most forest point counts rely on birds that are only heard, so this is a huge problem. These methods also run into problems if there is double counting, which is more likely if you have mobile animals (e.g., birds) especially those you can't see moving (e.g., because they're in the forest canopy). The standard way to deal with this is to keep the counts short, and even 5 minutes can be too long (in saltmarsh sparrows, double-counting starts to become a problem after ~4 minutes - and these birds are much easier to track than birds in a forest would be). Yet another problem is that studies show that the more species you are tracking the more mistakes you make. Even going from 6 species to 8 species has been shown to create detectable increases in the errors. Forest bird point counts are often used to track dozens of species simultaneously. All of this may sound as though it is impossible to use these methods in forests. That is not the case, but it is not simple and both field and analysis methods have to be chosen very carefully. In terms of the State of the Birds estimates, it is impossible to judge their accuracy without knowing exactly how the data were collected, how they were analysed, what assumptions were tested, etc. etc. If this is not done right then it would be very easy to produce extrapolations that are off by an order or magnitude. Even if the basic estimates are good, the margins of error can be large so must be calculated so that one knows how much faith to put in an estimate. For example, I once did an analysis of this type and came up with a confidence interval that span six orders of magnitude (needless to say, I concluded that the estimate was pretty useless) - that was for a shorebird, where the tendency to form big flocks can really magnify the uncertainty, but it illustrates the problem. So, for Roy and the two of you still reading (I'm an optimist I know) - sorry to tie up so much ctbirds space. Unfortunately, Paul's question is both very good and not at all easy to answer. Chris Chris Elphick Storrs, CT elphick@sbcglobal.net

DF

David F Provencher

Tue, Oct 4, 2011 3:31 PM

Thanks Chris,

As you know, my background is technical and I am (sadly) not unfamiliar with statistics and the protocols (including their weaknesses) for censusing birds. Additionally, my birding is very rarely done at the known birding hot spots. For me, walking and hiking are as important as the birding, so hiking boots and sweat (and often blood) are as much a part of my birding as binoculars are. Being a hard core hiker has given me a pretty decent ability to judge distances in the woods as well, which helps to more accurately assess population densities. I agree that there are more Ceruleans breeding in CT than a lot of birders may realize (I mentioned that to a few correspondents privately yesterday) and southeastern CT has a good distribution of them. Although the sites tend to be scattered and of very low population density.

I believe these two numbers are significantly off the mark high, especially with regards to Acadians. If there were that many Acadians in CT they would be the most common forest interior flycatcher in many places. To put it simply, they are not, they are uncommon to absent across all the areas of CT forest I hike, and I hike over most of the state. I have never found anything like the density levels these numbers represent for Acadians, and only in a few places for Ceruleans. I realize you could have written ten times as much info on censusing protocols and statistics as you did (thankfully you didn't!), but I think this may have been an "oops" moment in a very important and needed published work. Clearly you had reservations on this data at the time of review. On balance I think the strength of this excellent publication far outweighs its few weaknesses. Hopefully, as we move forward, the quality of the data will get even better.

Dave

-----Original Message-----
From: ctbirds-bounces@lists.ctbirding.org [mailto:ctbirds-bounces@lists.ctbirding.org] On Behalf Of Chris Elphick
Sent: Tuesday, October 04, 2011 8:17 AM
To: ctbirds@lists.ctbirding.org
Cc: chris.elphick@uconn.edu
Subject: [CT Birds] population estimates (long .... and probably boring)

Paul,

A few responses to your question ... a bit long-winded I'm afraid ....

CONFIDENTIALITY NOTICE: This electronic message contains
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does not in any case represent a firm ENERGY COMMODITY bid or offer
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intended solely for the individual or entity named above and access
by anyone else is unauthorized. If you are not the intended
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contents of this information is prohibited and may be unlawful. If
you have received this electronic transmission in error, please
reply immediately to the sender that you have received the message
in error, and delete it. Thank you.

Thanks Chris, As you know, my background is technical and I am (sadly) not unfamiliar with statistics and the protocols (including their weaknesses) for censusing birds. Additionally, my birding is very rarely done at the known birding hot spots. For me, walking and hiking are as important as the birding, so hiking boots and sweat (and often blood) are as much a part of my birding as binoculars are. Being a hard core hiker has given me a pretty decent ability to judge distances in the woods as well, which helps to more accurately assess population densities. I agree that there are more Ceruleans breeding in CT than a lot of birders may realize (I mentioned that to a few correspondents privately yesterday) and southeastern CT has a good distribution of them. Although the sites tend to be scattered and of very low population density. I believe these two numbers are significantly off the mark high, especially with regards to Acadians. If there were that many Acadians in CT they would be the most common forest interior flycatcher in many places. To put it simply, they are not, they are uncommon to absent across all the areas of CT forest I hike, and I hike over most of the state. I have never found anything like the density levels these numbers represent for Acadians, and only in a few places for Ceruleans. I realize you could have written ten times as much info on censusing protocols and statistics as you did (thankfully you didn't!), but I think this may have been an "oops" moment in a very important and needed published work. Clearly you had reservations on this data at the time of review. On balance I think the strength of this excellent publication far outweighs its few weaknesses. Hopefully, as we move forward, the quality of the data will get even better. Dave -----Original Message----- From: ctbirds-bounces@lists.ctbirding.org [mailto:ctbirds-bounces@lists.ctbirding.org] On Behalf Of Chris Elphick Sent: Tuesday, October 04, 2011 8:17 AM To: ctbirds@lists.ctbirding.org Cc: chris.elphick@uconn.edu Subject: [CT Birds] population estimates (long .... and probably boring) Paul, A few responses to your question ... a bit long-winded I'm afraid .... CONFIDENTIALITY NOTICE: This electronic message contains information which may be legally confidential and/or privileged and does not in any case represent a firm ENERGY COMMODITY bid or offer relating thereto which binds the sender without an additional express written confirmation to that effect. The information is intended solely for the individual or entity named above and access by anyone else is unauthorized. If you are not the intended recipient, any disclosure, copying, distribution, or use of the contents of this information is prohibited and may be unlawful. If you have received this electronic transmission in error, please reply immediately to the sender that you have received the message in error, and delete it. Thank you.

AZ

Anthony Zemba

Tue, Oct 4, 2011 4:17 PM

Hello all.
I have not read the publication yet myself, and perhaps I should reserve comment until I do so at the risk of sounding off the mark here. But perhaps the problem comes from a failure to take into consideration the special habitat attributes of the two species in question. For instance, Red Maple swamps are by far the most common Palustrine Forested wetland in CT. Four-toed salamanders inhabit Red Maple swamps, but Four-toed salamanders are by far not the most common Caudate in CT and are in fact absent from many Red Maple swamps. They likely require a certain special habitat attribute (perhaps presence of a Sphagnum layer?) within the Red Maple Swamp for the swamp to be suitable habitat. If one was to sample a Red Maple swamp where they were locally abundant and then use those results to estimate state population by extrapolating over the area of known red maple swamp coverage in CT, one would be way off base. I fear the same may have happened here. Yes Acadians and Ceruleans are a forest interior species, but as most birders known, not all forest interiors have Acadians and Ceruleans. They are likely forest interior specialists that require a special habitat attribute. As an example, Acadians that I have encountered in the forests of eastern CT have all been found within interior forests but within the area of the forest that is bisected by riverine upper perennial streams. I suspect that their breeding territories are centered on or about these drainage types. If one was to conduct point counts across a forested landscape bisected by such drainages and get a density of breeding Acadians and then extrapolate that across the entire forested watershed one might generate erroneous results for as one moves higher or lower in the watershed, stream density changes too. (e.g, higher in the watershed the streams become intermittent or originate from a palustrine forested wetland or groundwater discharge seep, and lower in the watershed they diminish as drainages join to form larger, lower perennial streams).

In the case of Ceruleans, I believe that they require a special habitat attribute or combination of attributes that may be based upon a specific forest structure produced by certain vegetation associations age or some other structure influencing factor. The presence of a shrub or sub-canopy layer is likely a factors based upon my casual observations (e.g., saw-timber sized mature forests with a developed canopy but with enough light reaching the forest floor to sustain a subcanopy or shrub layer).

Certainly three seemingly productive (or at least frequently birded) spots in the state for Ceruleans (River Road in Kent, Hartman Park in Lyme, and Boston Hollow Eastford/Ashford have very different vegetation species compositions, but the overall structure may be similar. Whatever the preferred combination of attributes are, they would by no means be uniformly distributed over all of CT's forest interiors as slope, aspect, elevation, hydrology, soil type, depth to bedrock, age class, coverage, etc, would change with location within the forest influencing forest structure.

Anthony Zemba CHMM
Certified Ecologist / Soil Scientist
GZA GeoEnvironmental, Inc.

655 Winding Brook Drive
Suite 402
Glastonbury, CT 06033

ONE FINANCIAL PLAZA
1350 Main Street
Springfield, MA 01103

413-726-2127
860-966-5888 (cell)
413-732-1249 (fax)
anthony.zemba@gza.com

-----Original Message-----
From: ctbirds-bounces@lists.ctbirding.org [mailto:ctbirds-bounces@lists.ctbirding.org] On Behalf Of David F Provencher
Sent: Tuesday, October 04, 2011 11:32 AM
To: Chris Elphick; ctbirds@lists.ctbirding.org
Cc: chris.elphick@uconn.edu
Subject: Re: [CT Birds] population estimates (long .... and probably boring)

Thanks Chris,

As you know, my background is technical and I am (sadly) not unfamiliar with statistics and the protocols (including their weaknesses) for censusing birds. Additionally, my birding is very rarely done at the known birding hot spots. For me, walking and hiking are as important as the birding, so hiking boots and sweat (and often blood) are as much a part of my birding as binoculars are. Being a hard core hiker has given me a pretty decent ability to judge distances in the woods as well, which helps to more accurately assess population densities. I agree that there are more Ceruleans breeding in CT than a lot of birders may realize (I mentioned that to a few correspondents privately yesterday) and southeastern CT has a good distribution of them. Although the sites tend to be scattered and of very low population density.

I believe these two numbers are significantly off the mark high, especially with regards to Acadians. If there were that many Acadians in CT they would be the most common forest interior flycatcher in many places. To put it simply, they are not, they are uncommon to absent across all the areas of CT forest I hike, and I hike over most of the state. I have never found anything like the density levels these numbers represent for Acadians, and only in a few places for Ceruleans. I realize you could have written ten times as much info on censusing protocols and statistics as you did (thankfully you didn't!), but I think this may have been an "oops" moment in a very important and needed published work. Clearly you had reservations on this data at the time of review. On balance I think the strength of this excellent publication far outweighs its few weaknesses. Hopefully, as we move forward, the quality of the data will get even better.

Dave

-----Original Message-----
From: ctbirds-bounces@lists.ctbirding.org [mailto:ctbirds-bounces@lists.ctbirding.org] On Behalf Of Chris Elphick
Sent: Tuesday, October 04, 2011 8:17 AM
To: ctbirds@lists.ctbirding.org
Cc: chris.elphick@uconn.edu
Subject: [CT Birds] population estimates (long .... and probably boring)

Paul,

A few responses to your question ... a bit long-winded I'm afraid ....

CONFIDENTIALITY NOTICE: This electronic message contains
information which may be legally confidential and/or privileged and
does not in any case represent a firm ENERGY COMMODITY bid or offer
relating thereto which binds the sender without an additional
express written confirmation to that effect. The information is
intended solely for the individual or entity named above and access
by anyone else is unauthorized. If you are not the intended
recipient, any disclosure, copying, distribution, or use of the
contents of this information is prohibited and may be unlawful. If
you have received this electronic transmission in error, please
reply immediately to the sender that you have received the message
in error, and delete it. Thank you.

This list is provided by the Connecticut Ornithological Association (COA) for the discussion of birds and birding in Connecticut.
For subscription information visit http://lists.ctbirding.org/mailman/listinfo/ctbirds_lists.ctbirding.org

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destroy this message and its attachments from your system.

For information about GZA GeoEnvironmental, Inc. and its services, please visit our website at www.gza.com http://www.gza.com/.

Hello all. I have not read the publication yet myself, and perhaps I should reserve comment until I do so at the risk of sounding off the mark here. But perhaps the problem comes from a failure to take into consideration the special habitat attributes of the two species in question. For instance, Red Maple swamps are by far the most common Palustrine Forested wetland in CT. Four-toed salamanders inhabit Red Maple swamps, but Four-toed salamanders are by far not the most common Caudate in CT and are in fact absent from many Red Maple swamps. They likely require a certain special habitat attribute (perhaps presence of a Sphagnum layer?) within the Red Maple Swamp for the swamp to be suitable habitat. If one was to sample a Red Maple swamp where they were locally abundant and then use those results to estimate state population by extrapolating over the area of known red maple swamp coverage in CT, one would be way off base. I fear the same may have happened here. Yes Acadians and Ceruleans are a forest interior species, but as most birders known, not all forest interiors have Acadians and Ceruleans. They are likely forest interior specialists that require a special habitat attribute. As an example, Acadians that I have encountered in the forests of eastern CT have all been found within interior forests but within the area of the forest that is bisected by riverine upper perennial streams. I suspect that their breeding territories are centered on or about these drainage types. If one was to conduct point counts across a forested landscape bisected by such drainages and get a density of breeding Acadians and then extrapolate that across the entire forested watershed one might generate erroneous results for as one moves higher or lower in the watershed, stream density changes too. (e.g, higher in the watershed the streams become intermittent or originate from a palustrine forested wetland or groundwater discharge seep, and lower in the watershed they diminish as drainages join to form larger, lower perennial streams). In the case of Ceruleans, I believe that they require a special habitat attribute or combination of attributes that may be based upon a specific forest structure produced by certain vegetation associations age or some other structure influencing factor. The presence of a shrub or sub-canopy layer is likely a factors based upon my casual observations (e.g., saw-timber sized mature forests with a developed canopy but with enough light reaching the forest floor to sustain a subcanopy or shrub layer). Certainly three seemingly productive (or at least frequently birded) spots in the state for Ceruleans (River Road in Kent, Hartman Park in Lyme, and Boston Hollow Eastford/Ashford have very different vegetation species compositions, but the overall structure may be similar. Whatever the preferred combination of attributes are, they would by no means be uniformly distributed over all of CT's forest interiors as slope, aspect, elevation, hydrology, soil type, depth to bedrock, age class, coverage, etc, would change with location within the forest influencing forest structure. Anthony Zemba CHMM Certified Ecologist / Soil Scientist GZA GeoEnvironmental, Inc. 655 Winding Brook Drive Suite 402 Glastonbury, CT 06033 ONE FINANCIAL PLAZA 1350 Main Street Springfield, MA 01103 413-726-2127 860-966-5888 (cell) 413-732-1249 (fax) anthony.zemba@gza.com -----Original Message----- From: ctbirds-bounces@lists.ctbirding.org [mailto:ctbirds-bounces@lists.ctbirding.org] On Behalf Of David F Provencher Sent: Tuesday, October 04, 2011 11:32 AM To: Chris Elphick; ctbirds@lists.ctbirding.org Cc: chris.elphick@uconn.edu Subject: Re: [CT Birds] population estimates (long .... and probably boring) Thanks Chris, As you know, my background is technical and I am (sadly) not unfamiliar with statistics and the protocols (including their weaknesses) for censusing birds. Additionally, my birding is very rarely done at the known birding hot spots. For me, walking and hiking are as important as the birding, so hiking boots and sweat (and often blood) are as much a part of my birding as binoculars are. Being a hard core hiker has given me a pretty decent ability to judge distances in the woods as well, which helps to more accurately assess population densities. I agree that there are more Ceruleans breeding in CT than a lot of birders may realize (I mentioned that to a few correspondents privately yesterday) and southeastern CT has a good distribution of them. Although the sites tend to be scattered and of very low population density. I believe these two numbers are significantly off the mark high, especially with regards to Acadians. If there were that many Acadians in CT they would be the most common forest interior flycatcher in many places. To put it simply, they are not, they are uncommon to absent across all the areas of CT forest I hike, and I hike over most of the state. I have never found anything like the density levels these numbers represent for Acadians, and only in a few places for Ceruleans. I realize you could have written ten times as much info on censusing protocols and statistics as you did (thankfully you didn't!), but I think this may have been an "oops" moment in a very important and needed published work. Clearly you had reservations on this data at the time of review. On balance I think the strength of this excellent publication far outweighs its few weaknesses. Hopefully, as we move forward, the quality of the data will get even better. Dave -----Original Message----- From: ctbirds-bounces@lists.ctbirding.org [mailto:ctbirds-bounces@lists.ctbirding.org] On Behalf Of Chris Elphick Sent: Tuesday, October 04, 2011 8:17 AM To: ctbirds@lists.ctbirding.org Cc: chris.elphick@uconn.edu Subject: [CT Birds] population estimates (long .... and probably boring) Paul, A few responses to your question ... a bit long-winded I'm afraid .... CONFIDENTIALITY NOTICE: This electronic message contains information which may be legally confidential and/or privileged and does not in any case represent a firm ENERGY COMMODITY bid or offer relating thereto which binds the sender without an additional express written confirmation to that effect. The information is intended solely for the individual or entity named above and access by anyone else is unauthorized. If you are not the intended recipient, any disclosure, copying, distribution, or use of the contents of this information is prohibited and may be unlawful. If you have received this electronic transmission in error, please reply immediately to the sender that you have received the message in error, and delete it. Thank you. _______________________________________________ This list is provided by the Connecticut Ornithological Association (COA) for the discussion of birds and birding in Connecticut. For subscription information visit http://lists.ctbirding.org/mailman/listinfo/ctbirds_lists.ctbirding.org ________________________________ This electronic message is intended to be viewed only by the individual or entity to which it is addressed and may contain privileged and/or confidential information intended for the exclusive use of the addressee(s). If you are not the intended recipient, please be aware that any disclosure, printing, copying, distribution or use of this information is prohibited. If you have received this message in error, please notify the sender immediately and destroy this message and its attachments from your system. ________________________________ For information about GZA GeoEnvironmental, Inc. and its services, please visit our website at www.gza.com<http://www.gza.com/>.