Rick,

As a part of my Mont Co big year strategy, the last few weeks I have 
been working Hughes Hollow followed by Violette's Lock as much as I can 
for some target birds including Golden-winged Warbler, Marsh Wren, 
Connecticut Warbler, Least and YB Flycatchers, Philadelphia Vireo(got 
both FCs at HH and Philly Vireo at Violette's) plus hopefully a wader or 
two. The Swallow-tailed Kite was a nice bonus. In another week or so, I 
will switch over to Blue Mash for Lincoln's Sparrow and maybe if I'm 
lucky an Orange-crowned Warbler.

Anyway, yesterday I was at Hughes Hollow out on the main dike about 20 
yards past the intersection when I heard what I assumed was a Marsh 
Wren. The bird was calling softly and I was kneeling withing 5-6 feet of 
it but in the 10 minutes it vocalized, I could not get a look at it. It 
stopped singing, and I left to further explore but also confident that I 
had added a new county bird to my list even though I never saw it.

About a half hour later, I was walking back along Hunting Quarter Rd 
towards the parking lot, when I thought I heard another Marsh Wren 
calling from some of the new cattails that have started to take over the 
1st impoundment on the left. I stopped to listen more closely but 
quickly realized I was hearing a House Wren and not a Marsh. All of 
sudden, doubt entered my mind regarding the earlier Marsh Wren. For 
whatever reason (confirmation bias?), the whole time I listened to the 
what I thought was a Marsh Wren, I never even considered House Wren. I 
think I blinded myself a little because: 1) I want a Marsh Wren badly 
for my big year 2) I expect one to possibly be there this time of year 
based on MDOsprey archives 3) John Stup reported a Marsh Wren the day 
before at Little Bennett, 4) I have not heard or seen any House Wrens at 
HH since Aug 31 so was not in House Wren mode, and 5) I don't have a lot 
of experience with Marsh Wrens.

I went back out on dike to try and reconfirm it but was unsuccessful. 
Just felt like a dumb mistake to me. It may well have been a Marsh Wren 
but if I claimed it for my list, there would always be some nagging 
doubt. Birding should not be this stressful but only have myself to blame.

Andy Martin
Gaithersburg


 wrote:
>
>     a small consolation after an episode of confirmation bias at
>     Hughes Hollow yesterday may have cost me a chance at my county
>     Marsh Wren. 
>      
>
> Andy,
> Can you elaborate...
>  
> Rick
>
>
> -----Original Message-----
> From: Andy Martin <>
> To: 
> Sent: Sat, Sep 19, 2009 1:43 pm
> Subject: [MDOSPREY] yard RB Nuthatch, Gaithersburg
>
> Had a Red-breasted Nuthatch visit my feeder this afternoon. A bird 
> that has eluded me all year. #214 for my 2009 county year list and a 
> small consolation after an episode of confirmation bias at Hughes 
> Hollow yesterday may have cost me a chance at my county Marsh Wren. 
>  
> Andy Martin 
> Gaithersburg 
>  <mailto:[log in to unmask]>