[CT Birds] Thoughts on Bird Numbers

Dennis Varza dennisvz at optonline.net
Tue Mar 20 11:51:13 EDT 2007


There have been several comments on the change in numbers of birds. 
Looking at past lists is interesting and fun. But, only hints at what 
changes have occurred. Often I hear comments about birders’ 
contribution to science, but except for certain people most birders are 
out for play. Which is fine if you accept that is what you are doing. 
Bird numbers are changing all the time and they need to be documented. 
“I remember when” doe not cut it when trying to save habitat or 
influence policy. Policy makers need hard data. A while back I realized 
being a Biologist is very depressing. All the jobs are in protecting 
and saving remnants, (sort of like a fireman). One doesn’t get paid to 
study the mysteries of life one sees every day.

When I moved back to Connecticut I considered how to spend my time 
birding.
Chasing rarities no longer held much interest. I thought about what 
Lordship like 100 years ago, and that we really don’t know except from 
the scraps of old records. I then thought about what kinds of records 
to leave behind for the next person 100 years from now.

To be scientifically useful for the future, field notes should be 
quantitative and reproducible.

Number of birds, even the common ones, is important to assess magnitude 
of change. What does common, or regular really mean? These types of 
description are subjective and may be obvious now but 100 year from 
now? In writing a report on Red-headed Woodpeckers I found this often 
cited comment that they were “as common as Flickers”. What does that 
really mean? It begs the question: “Well, how common were Flickers 
then?” Using numbers can give you averages, standard deviations, and 
statistical tests. Their meaning is always the same. Instead of saying 
“It seems to me that warblers are less common than 50 years ago”.  One 
can say “There was a 50% decrees in abundance over the past 50 years”. 
Which statement do you think would have more weight?

Granted, counting birds takes time and the accuracy can be 
questionable, but something is better than nothing. I find that 
counting shorebirds in flocks over ten is usually an estimate, the way 
those little buggers run about. It really doesn’t matter much if you 
count 15 birds and there are really 18. As long the number is 
reasonably close, it is OK. Putting down 50 birds however will cause 
problems. The larger the numbers the more slop is allowed. Counting the 
huge rafts of Scaup is an educated guess. With practice and experience 
one can come up with reasonable numbers. When in doubt use this trick: 
Bracket the number; Is there more than 1 and less than 100? Is it more 
than 20 and Less than 50? Eventually you will come up with a reasonable 
estimate. What really bugs me is when people put down something like 
40+ Coot. What does the plus mean? They had 40 coot but there was more, 
how many more, 10 more, 50 more, 100 more? Why not just give it your 
best estimate and be done with it. Yesterday I was out birding and saw 
10+ Starlings.

The hard part is keeping running totals of the common stuff. How many 
Cardinals do you see in a day birding. Unless you write down numbers as 
you go you will never know. Blue Jay is a common bird, yet when you 
actually stop and count the birds you see, some time only 1 or 2 are 
seen for the day.

The really hard part is counting the really abundant common birds. Even 
I have my limits. For the most part I do not count Common Crows. Mainly 
because when I am birding I move slower than the birds and there is a 
good chance I could be counting birds more than once (I will make note 
of large congregations). I do not count Rock Pigeons, Monk Parakeets, 
Starlings, House Sparrows, and Black=backed, Herring and Ring-billed 
Gulls. Imagine trying to get a good count at Seaside Park Bridgeport at 
low tide, that would kill your day. It should be done, it is just that 
I haven’t figured out the best way to do it yet. Also, during the 
summer I don’t count Robins, Red-winged Blackbirds and Grackles. When I 
am on the shore and concentrating on counting ducks or shorebirds I 
pretty much ignore the land birds because the numbers would not be 
representative of what is really there.

The second part of useful record keeping is reproducibility. The number 
of birds one sees is affected by many conditions.  The ideal situation 
is to keep all the conditions the same so that any difference in number 
is due to the birds themselves and not the conditions. One major 
condition is where you go. Can someone look at your notes and retrace 
your steps? Birding Lordship if done thoroughly would take at least a 
day, 2 during migration, Some sites I cover all the time some 
occasionally. My list would vary depending upon what sites I do and 
don’t cover. So, I enumerate the sites I do cover in the sequence I 
cover them. so someone can retrace my steps in the future and see how 
things have changed.  For inland birds I created several routes and 
made detailed notes about how they are covered. For 5 years I covered 
the routes to create a database. In the future someone can follow my 
footsteps and QUANTITATIVELY see how things have changed. By the way, I 
also photographed the routes so one can see the changes in habitats. 
Other things to Include is weather data, tide information, and sea 
conditions, (White Caps, Calm, Rippled, Glass etc.).

Quantitate birding is very demanding with delayed gratification. I 
would suggest for starters picking out your favorite (most often 
birded) site and just do that.




Dennis Varza
Fairfield


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