"I come into the peace of wild things who do not tax their lives with forethought of grief.
For a time I rest in the grace of the world, and am free." ~Wendell Berry


Showing posts with label Missouri purple martins. Show all posts
Showing posts with label Missouri purple martins. Show all posts

Saturday, March 23, 2019

Purple Martin Season 2019 Has Begun

Two ASY male purple martins arrived on March 10, 2019 this year. This year's arrival is more back in line with my first 10 year average arrivals.


In all the years past, my martins had also arrived with the tree swallows, however, this year, a male tree swallow had actually arrived a week earlier. During the last few days the tree swallows have been swarming the nest boxes in the fields and my blue birds are not really thrilled with their arrivals.
They are such happy, cheerful little birds and love to fly up high with their bigger cousins. I was going to remove this perching pole this year, but since they seem to like it so much, I may have to leave it...I don't want to upset my fabulous sentries!
This year, I'm making more changes. A landlord decided he wanted to retire his colony, so I bought some of his equipment from him - namely another Super System. It is so much easier to do nest checks with the extended cages on these systems than it is with the round Deluxe gourd rack systems, so this year, I'm removing one of the Deluxe systems and by adding 4 more gourds to each Super system, I'll still be able to offer 84 gourds and my nest checks won't be so painful (literally - it was death by a thousand scratches in the round racks).

So, with this system, I'm designing the cages in the same way - since they work so well on the other racks. I'm extending the 4' gourd arms by adding an 18" aluminum angle arm. I drilled 2 holes to mount the extensions to the main arms, with another 2 holes on the very end, where I can mount the cage wire.
Then, I have laid a 6' piece of aluminum angle arms from corner-to-corner. We drilled holes in each end, so I can anchor them down with tie-wraps. This helps support the top cage wire, so it doesn't sag, and these arms are super-light.
Since I've removed one of the Deluxe round racks and I wanted to keep the same number of gourds, I added 1 gourd per arm on each rack, so I'm still at 84 gourds. For the end gourd, I replaced the straight arm with a 45 deg. arm, which effectively points the end gourd back inside the cage.
For this Super system above, I just replaced all the arms with the extra long arms I had purchased from Hilltop and have made it a perching rack / feeding tray / oyster -egg shell feeder. Bob was tired of seeing me stand on my 4-wheeler to try to fill the other tray on my old post, so we converted this one.
For now, I only have 10 martins here, so I'm taking my time and making sure I have everything the way I want it. Lesson-learned: it is super annoying to get into the heat of the summer with jumpers and not be able to easily put them back into their nests. This Great Horned Owl has made my life more difficult but as she has learned and adapted, so have I.
I'm also keeping the Deluxe gourd rack that I took down - you never know, I may change my mind when I retire and put it back up and expand my colony, but for now, I'm pretty happy with offering 84 gourds that are 100% protected from the owl, yet still being able to perform nest checks.
Lookout 2019 - here we come!

Monday, October 1, 2018

The Grand Finale to a Great Purple Martin Season


After an initial rough start to the 2018 season due to some unanticipated moves by the GHO, I was able to finish the year with a total of 76 pair and we fledged 360 young.
Kicking off this season with a warmer-than-usual Spring, many of my adult pairs were able to get started with nest-building and egg-laying in parallel during the same 2 weeks. This resulted in many, many nests fledging simultaneously from July 3rd through July 14th, with hundreds of martins returning in the evening, filling the arms on the gourd racks.
The new fledging tree behind my house held dozens of newly-fledged martins. As I watched them every day, I worried that the hawks would be drawn to such easy prey, but it never became a problem The tippy-top of this tree is easily 100 feet tall and the new fledges were able to drop and gain speed quickly. They were safer up there than they were on the top perch rods on my gourd racks.



The young fledges demanded food from whomever came flying in, whether it was one of their brothers & sisters or not.


After watching over the young fledges roosting on the arms for several nights and wondering if I was making a mistake by allowing them to roost there, it became apparent the owl had either tried & failed to broach the nets beneath, or wasn't quite sure she could keep from getting tangled in the ropes. Either way, the netting was the final touch to my cages this year that allowed for a nice balance of allowing the martins to escape during a hawk attack, but also kept the owl out (see this post from June, that was the reason I had to install the netting: http://kathyfreeze.blogspot.com/2018/06/nest-checks-new-hatchlings-and-nets.html)

This was the first year in my 12 years of hosting purple martins that I've had this many fledges returning every night.  It was also the first year, the new fledges have been able to safely roost all night on the gourd arms of my racks - protected from raccoons, snakes, and owls.

This was also the first year in the last 5 years of dealing with the GHO where I've felt I have created the best balance between providing protection for the martins and coexisting with both a GHO and a Barred owl.
Instead of the usual fretting, worrying and anxiety, this year was filled with the sheer joy of seeing so many healthy young'uns on the rails and in the surrounding trees.

I'm glad I never gave up the fight and surrendered, because now, I have a lot of experience with what does and does not work when you have to contend with owls.

Sunday, June 24, 2018

Missouri Purple Martins - A Mid-Season Update

All the native wildflowers are in bloom, creating a fantastic palette of colors and fragrances and drawing in a variety of bugs - aka, "bird food".
Sensitive Briar
While some areas have suffered from drought and a lack of food for their purple martins, the deeper roots of our native wildflowers and grasses have resulted in blooms everywhere, attracting many varieties of bees, butterflies and other insects that I can't even identify.  Our birds are having a field day.  Literally....
Purple Coneflower

Indian Pink

Ohio Horsemint, Bee Balm and Butterfly milkweed
The variety of bugs the purple martins are bringing in are fascinating.  The best ID of the insect in the picture below that I could come up with is "Great Purple Hairstreak".  If anyone has a better ID, please let me know.
We have reached the part of the season where not only are the temperatures starting to soar, but the number of housekeeping chores for my birds as well.  One of the things I've learned about being a purple martin landlord is that if I do the required nest changes at the right times (ie, nestlings 12-16 days old), to rid the martin nests of their bedbugs, then I'll have less "jumpers".  Jumpers as in dehydrated, underfed and mite-stressed nestlings. This is the part of the season that I both love & hate - I HATE the heat, but I LOVE the experience and knowing I'm really doing something that contributes to the future health of mine and my neighbor's colonies.
From the PMCA website:
Tests conducted by the PMCA in the late 1980’s showed that only 44% of martin  nestlings in parasite-infested nests survived to fledging age, compared to 84% in parasite-free nests. The man who conducted those tests, James  R.  Hill,  III, stated, “The  difference might actually have been greater than what was measured, because the young raised in the absence of parasites seemed fat and healthy, and probably had a higher-than-average first-year survival rate, whereas the young subjected to parasites seemed thin and often sickly, making them less likely to survive after fledging.”

Read more here at the PMCA site about Nest Changes: https://www.purplemartin.org/uploads/media/how-why-to-do-nest-r-332.pdf

As of June 19th, I had 57 nests that needed a nest change. Yes, 57 nests.  I currently have 76 pairs (3 new since June 15th!), so a whopping 75% of all my nests need changing.  At first, I was shocked.  Then I was kind of thrilled. Then I was kind of overwhelmed.  In 95+ degree weather.  All due on the same day. This is the first season I've had where the majority of my nestlings are all around the same age at this point in the season.  The nightly return of fledges is going to be thrilling...and will also require some monitoring to deter hawk predation.

Taking an Evening Break - Purple Martins bathing at the pond.

With the heat index around 102 degrees (real temps around 92-93), I started on my first rack on 6/20 (12 nests out of 18 on that rack). When I lowered them, my eyes immediately zeroed in on 3 gourds that were almost grey-colored due to the overwhelming number of mites. I had to wonder how many of those rained down on me when I was lowering my racks.
Here is what a gourd looks like when it's overloaded with mites. You have to wonder, how can they even sleep at night with all those mites??
Troyer Horizontal gourd covered with an explosion of mites.
Special thanks to Betty Farthing Grigg on the PMCA Forum for the use of the photo above.

Special thanks to Courtney Rousseau of the North Carolina Purple Martin Group for providing the video below of a gourd infested with mites!

Nevertheless, I pushed through and with alcohol wipes and a cold-water hose, I managed to survive, even though it took almost 2 hours for my head and my body to cool back down.

Thankfully, the last 3 days have been a lot cooler as I worked through the remaining racks. After the first 2 racks, I was thrilled to find that only 2 nests out of 36 had lost a total of 2 nestlings.  The rest were very fat and healthy.  Even my 2 nests with 7 nestlings in the first two gourd racks were doing exceptionally well. Yesterday, when I finished up the nest changes on my last rack, I concluded that I have "fat baby syndrome" and it's consistent across all my racks. It also indicated to me that while I had initially lost a few martins at the beginning of the season - probably some to the owl and some to the hawks - the majority of my nests have 2 parents that are keeping up with the grocery shopping.  I did find one nest with 4 dead young, so I suspect the owl / hawks got both parents of those. Fortunately, it was only one. I also had mixed feelings over discovering 2 new nests with 4 & 5 eggs respectively. They will be hatching around July 5th or so and probably not fledging until end of July / beginning of August, meaning another extended season for me.
So, total pairs - 76 with currently 360 nestlings!  Hoping to maintain something close to that over the next few weeks.

Nest Change Tips:
1. Dabbing a small amount of vanilla extract around your eyes, nose and mouth will help keep the gnats away from those areas of your face.
2.  Check your tool box before you start your nest changes to ensure you will have the needed equipment within easy reach. The last thing you want to do is go digging around to find something while you're simultaneously swatting at mites & bugs and the sun is overheating your brain!
3. Soak 6-8 paper towels with 91% rubbing alcohol, store in a Ziploc bag and add them to your tool box. These will be handy for wiping down your hands, arms and the gourds when there are just more mites than you can bear.
4. Your son's old white, light-weight, big & baggy karate pants make excellent nest-check pants! They are cool, loose and you can kneel on the ground without all the itchy grass tickling your leg.
5. Always assume that whatever you touch after nest changes are completed will also become contaminated with mites until you thoroughly wash your hands and arms.  Filling a large bucket with water and a having a bar of soap nearby will provide you with some much-needed relief after a round of nest changes.
Check out this post from 2016 for a more detailed list of the tools in my tool kit:  http://kathyfreeze.blogspot.com/2016/05/nest-check-season-begins-and-sub-adults.html





Friday, April 13, 2018

Of Missouri Sunsets, Spring and Purple Martins

After a few days of cold, wet miserable weather - including SNOW, I decided to go outside the last few evenings to check on my purple martin population and observe them as they rain down from the sky at dusk.  On Monday night, my camera battery died pretty quickly.  Just swell. But Tuesday night, I was re-charged and prepared.  Only I really wasn't prepared for what Mother Nature has been up to the last few days.
After last year's drama of having to deal with a lot-more-than-usual hawk attacks (8-10 per day - we think a male & female Cooper's hawk) we removed a few more trees this past winter.  So far, this has been a huge improvement...(knocking on wood).
The guidelines for attracting martins state that you need 40' of open space around your colony, but there are many other factors involved in that, not only for attracting, but also keeping them safe.  Even though they were 150' away, the hawks were using the cedar trees as cover and coming up the East side low & fast behind them, then launching surprise attacks on my new fledges. So, in the end, the trees had to go.
Still, I'm engaging every tool in my arsenal to fight back against any hawk attacks, including my little 'winged orcas' and bird-feeding stations surrounding my colony on all sides, setup halfway between the woods and the gourd racks.
My "Winged Orcas"

In my particular case, the noise from my colony attracts hawks, more than any birds at a bird feeder.
The birds at the East feeding station were on duty, doing their part. They work-for-food...notice I didn't say, "for free", but since chicken scratch is only $7.50 a bag at our local MFA, let's just call them, "cheap labor" and "free decoys".
The birds at the West feeding station were also on duty - same labor prices.  When I'm out & about with my martins, I keep one eye on these feeding stations so I can gauge whether a predator is nearby.
While waiting for the martins to return, I made a video of my little winged orcas (tree swallows) and all the other bird activity around my site. I was surprised at how many birds I could hear on the video when I played it back on my computer. I had only been 'listening' for alarm calls while outside and didn't really realize how many birds have already arrived this spring!
Take a listen - how many birds can you identify by their calls in the below video? I'll give you a hint - there are NO English house sparrows or starlings!

At 7:08 PM a small group of eight martins started circling the gourd racks. By 7:24 PM - still only seeing 8 martins, I thought I may have been off by a factor of 12 when I had informed a fellow purple martin landlord that I thought I had approximately 100 martins here now.
But at 7:31 PM, it started raining martins from the sky and I had to force myself to turn off the video camera periodically as I tried to keep watch for any approaching hawks and enjoy the show at the same time.  And wow, WHAT a show - a brilliant sunset AND over 100 purple martins!  I had such a delightful evening.
The sound in the video below is just as I heard it - no enhancements have been made. I did have to blend multiple videos together, as I had to frequently turn it off and on, so I could walk around and continue to monitor for hawks. To enjoy the video below, click on the YouTube icon and open in full-screen mode.

I love these evenings - partly cloudy paired with the setting sun causing these rapidly changing colors, along with loud, raucous purple martin chatter and no hawks. Good night, my lovelies! Tomorrow is another day!

Thursday, March 29, 2018

Don't Blink

For the last 8 weeks, I have been seeing 15 to 20 crows around Gobbler's Knob. For awhile, they were just 'noise' in the background that I could hear on my frequent ventures outside.
But, as I sat in my office one morning I saw a buzzard flying in from the North, bobbing up and down and weaving as if he / she were drunk.  It was weaving and coming in so low in fact, I thought it was going to crash into my office window. Hot on its tail were my murder of crows.
A few days later, Bob was taking Nikki for a walk around the property. The Great Horned Owl flushed and flew a couple hundred feet into a nearby tree, with the crows in pursuit, constantly cawing and harassing her.  At that point, it dawned on me I should figure out how I could use these noisy, wonderful troublemakers to my advantage.  It has been amusing to watch them chase the Red Tails, Northern Harriers, Cooper's, and the Red-Shouldered hawks as they hunt across the fields. Unfortunately, it always seemed to be happening when I am without one of my cameras.
So, to keep the crows around and the owls distracted, the south east field is now prepped to draw  their attention away from my purple martins.  We scattered over 35 lbs of chicken scratch (containing cracked corn and milo) here - what doesn't get eaten will grow...and that's ok too.
 We even provided private, reserved perching for our GHO and our Barred owl.


Last Friday, Mar. 23rd, I had counted 18 purple martins when they came in for the evening.  This past Saturday however, there was a noticeable difference in their chatter & activities and I watched my gourd racks as purple martins rained down from the sky. It was windy and 65 degrees. This video was taken around 11 AM - there are a lot in the air behind me as I was filming them coming in and claiming their gourds....and the way they navigate the owl cages - they've obviously been here before.
(click on the video below, then the "YouTube" link to embiggen the screen)

As I stood outside Saturday evening, Mar. 24th, I expected to count 18-20 again. At first, I only counted 12 returning home as the sun began to set and I thought the rest had either moved on, or I had been mistaken on Friday. As the sky darkened though, I heard martins behind me and above - seeming to suddenly materialize out of the clouds. I spun round & round, trying to spot and count them, as more small groups appeared from every direction. Way up high, a familiar shape circled the quarter moon. By the time every martin had descended and was safely tucked in a gourd, I had counted 35 martins.  Yes, 35 martins.  On March 24th. The only year that number was exceeded was in 2014 - and that ended up being a horrible year where I had to feed them ... a LOT.  In fact, here are my counts from previous years:
  • March 26, 2008 - 1 ASY male purple martin arrived
  • March 24, 2009 - 1 ASY male & 1 ASY female arrived
  • March 15, 2010 - 1 ASY female martin arrived (by 3/24 - there were 4 here)
  • March 7, 2011 - 1 ASY female martin arrived (by 3/24 - there were 12 here)
  • March 13, 2012 - 2 ASY male martins arrived (by 3/24 - there were 24 here)
  • March 9, 2013 - 1 ASY female arrived (by 3/24 - there were 22 here)
  • March 10, 2014 - 1 ASY male arrived (by 3/24 - there were 100 - 110 here)
  • March 15, 2015 - 1 ASY male arrived
  • February 28, 2016 - 1 ASY female arrived (by 3/24 - there were 25-30 here)
  • March 4, 2017 - 1 ASY female and male arrived (by 3/24 - there were 25-30 here)
  • February 19, 2018 - 1 ASY male arrived (by 3/24- there are 35+ here)
I currently have 5000 crickets in the freezer and I'm really hoping I don't have to use them this year. At the very least, it's starting to look like it's going to be another interesting year.

Much to my delight, I received another visit from my Barred Owl (who has NOT been spotted attacking my purple martin racks) on March 28th at 10:15 AM. I can't help myself - I could watch her all day.  This nestbox is less than 150' from my office window and wouldn't ya know it - she always shows up when I'm on a work conference call.

I can't help but wonder how any of my cavity-nesters - bluebirds, chickadees, tufted titmice, or tree swallows would ever feel comfortable using this nestbox for the season. Yet, I've never seen her chasing any of my birds - in fact, the purple martins were out chattering on the racks on the opposite side of the house at the same time this video was taken. When the GHO was spotted during daylight a few days ago, the first sign that a predator was around was the loud warning calls of the Cardinals and Blue Jays that were flitting about where she had decided to roost.  Oddly enough, those same birds do not seem to react in the same manner when the Barred owl is around. Since I've seen her on this post a lot using it as a hunting perch, she must be having success to keep coming back to it. I was actually happy to see her.  I had read that GHOs would either kill or drive a Barred owl out of its territory, so I was glad to see she was still alive.  As I frequently discover, the 'rules' don't always apply here at Gobbler's Knob.
The New England Asters, Bee Balm and other native wildflowers are starting to sprout in my garden already. The dandelions and Bradford pear trees are blooming and providing some much-needed food for the honey bee hive I found in my wood duck box.
All the signs are clear - so, come on Spring - the martins are ready, the plants are ready and now I'm ready - let's get to it!






Saturday, March 3, 2018

Purple Martins Arrive in Southern Missouri

I thought the wind and my husband were trying to trick me.  But sure enough, on 2-19-2018, I spotted my first purple martin of the season, circling the 4 gourds I had put out just that day.

After 2 days, I never heard or saw him again.
Then suddenly, on 2-27-2018, another male showed up with a female.  I wasn't sure if it was the same male that had left to find a mate, or a different pair.  Nevertheless, they are here!  Time to deploy your housing.
Happy Purple Martin Season, fellow Missourians!



Saturday, July 1, 2017

Today, I Fly

I was born on June 4th, 2017.  I was just a wee thing, with 2 brothers and 2 sisters.  My Mom is beautiful and she and Dad feed us often. Big, fat, juicy squishy bugs.  Yum, yum!  There was a funny-looking creature that kept opening our nest door and peeking in.  Mom & Dad would scream at her, but still she came to visit us a lot.  She would make funny noises and count to 5 every time time she opened the door.  Did she just come here to practice her counting?
Today, my Dad told me, "Son, it's time to spread your wings."
I could hear my friend's Mom telling him he too must learn to fly today  He didn't look too happy about it either. 
 
I even have my own personal escort crew in hot-standby.  Not too sure I really trust these guys to "help" though.
We have seen what happens to the neighbors' kids that attempt to fly at this age.  They end up in funny positions, with others pushing them off railings, porches and perches.  Still, Dad is refusing to bring more bugs, while I just continue to sit here.
Man, that's just wrong.  Where's that nice lady with the crickets when you need her?  How about counting out 5 of those, lady?  I finally decided that I would catch my own - I'm getting hungry.  Except, I haven't exactly gotten very far.  Still no food deliveries.  They said I had to FLY, they didn't specify how far!
 Well, I thought hanging out here for a big would be a good idea, but maybe not.
 Nope, definitely not.
 Even Dad isn't acting very happy about my resting here.  What?  Still no FOOD?
 Mom knows how to get me moving.  It's a small snack, but it will do until I get my bearings.
Another 200 feet and Mom finally hands it over.  One small step for purple martindom, one giant leap for me.  My future is looking bright already.

Monday, June 5, 2017

A Message in a Little Yellow Band

How was I to know that placing a teeny, tiny little yellow band with the number "A407", on the tiny little leg of a purple martin nestling from Trendsetter house - cavity #8 on June 29th, 2011, would bring such a message of hope and inspiration to me this season?  It's funny how something I did 6 years ago - which seems so long ago, yet really not that far - can have such a meaningful impact on my life today.
I had been noticing a few martins with yellow bands on the gourd racks and since the weather was so perfect on Friday, I decided to get out my equipment and spend a few hours with my martins.  This is how I use my vacation time and where I am 100% focused on my martins and nothing else can bother or worry me - in my yard, with my martins and my spotting scope.
But there is a process to prepare for "band-spotting" work and I have a list of what is needed.  First, sunscreen - SPF 50 is required, or my first outing into the sun will result in a very charred, red nose.  Next, a few dabs of Vanilla extract around my nose, mouth and eyes to keep the gnats away from my face.  Sticky, but very effective!  I also carry a small, cheap notepad with a pencil (I prefer pencil, just in case I write down a wrong number) and a set of binoculars for the overall, initial scanning.  I love the yellow Missouri bands that MRBO put on my birds - it makes them so easy to spot.
Bob mounted my umbrella holder on the back of my 4-wheeler for me. I love this thing!  Bob and our recently-deceased friend, Bob Petersen, had come up with this clever design so that I could sit out in the sun, anywhere in my yard, during the heat of the day and spot bands or just enjoy my martins.  Yes, I'm fully aware of how spoiled I am.
The shade also helps keep my spotting scope from getting too hot.  Since it is black, it would quickly overheat in the sun and that's a bad thing for optics.  I see a lot of people on the Purple Martin forums asking what type of spotting scopes to buy to read the bands on their birds.  For me, this little Nikon ProStaff 5 has worked perfectly.  With a 16x48x eyepiece on it, I can sit right in the middle of my colony and read the numbers on the yellow and the silver (federal) bands and observe the unique markings of each individual martin.
It's especially challenging at this time of year to read bands as the martins tend to flit around from rack to rack, visiting all the other gourds and other potential mates and that makes it hard to tell to which gourd they belong.  But this time, a couple of them revealed to which gourd they were committed by the persistent wave of green leaves they were bringing in.  I was surprised that they are still bringing in green leaves at this stage of the season, with so many eggs already laid. 
This guy, Mr. A407 was packing in the green leaves for G20.  There are no words to express how thrilled I was when I reviewed his record today.  He was originally born in my Trendsetter (cavity #8) and was banded here as a nestling on 6/29/2011, making him 6 years old this year.  But what made my spotting of him really special - he had also nested in the Trendsetter for the last 2 years.  That means that he not only survived all the owl attacks on the house during that time, he also adapted when he returned this year to find the Trendsetter had been replaced by a gourd rack.  He chose to nest in a gourd this year, meaning yes, he REALLY wants to stay HERE.  Oh, welcome home, you gorgeous, daring & brave young man!  A message of Hope - not in a bottle, but in a little yellow band!
Mr. A407 - now 6 years old has lived to tell the tale of the Great Horned Owl on Gobbler's Knob.
My next ID was of Mr. C226 - now nesting in G1.  He was born here in G9 and banded on 6/10/2012, making him 5 years old this year.  Ironically, G1 is right where G9 used to be, since I moved all the gourds down one level this year so the owl could not agitate the gourds from the top level.  Now how cool is that?  Bob thinks he just likes the view of our home and the feeding tray when there are crickets and eggs served during cold weather.   
Mr. C226 - 5 years old this season.
The last band sighting was of Mr. A673 - he was banded here on 7/9/2011 as a nestling - also making him 6 years old.  He was born on the same rack where I spotted him, but I have not identified his new chosen gourd for this season yet.
Mr. A673 - 6 years old as of 2017.
Last week, I was a little worried as a nest check revealed I only had 60 pair on Memorial Day.  In previous years on the same day, I've had around 70.  Turns out, they were a few days behind this year and as of today, I have 71 pairs of martins nearly filling my 75 gourds I am offering this year.
They all seem to have adapted to the caging around the gourd racks, but it still makes it difficult to get a good picture with all the wire.  Somehow, but we all seem to work around it.
An adult female adds fresh green leaves to her nest.
The sub-adults have arrived and are causing chaos with the adults.  I love watching the adults watching the sub-adults.
"Is that your boy from last year, George"? 
One of my favorite challenges when watching my colony, is to try to identify the sub-adult males.  You can usually find them by just watching for the fights and screeching. 
A young sub-adult male.
An adult pair guards their nest from the marauding sub-adult males.


As of today, we have not seen the owl in 11 nights.  A friend from the PMCA forum has loaned me his "Dancing Man" and I am trying him out.  I have him on a timer and change the settings for him to turn on and off at different times each night. 

I've also deployed my 'hunting blind' from which I normally hunt English House Sparrows and Starlings, and I've been moving it around the yard every 2 nights.  I purchased some solar yard lights and I recharge one every day and put it inside the blind each night, slightly unzipping the portals so the owl is sure to see the "evil eyes" staring her down if she tries to enter the yard. There is no way to tell yet what is being effective in keeping the owl away, but whatever the reason is, I am grateful for each night she does not come around and I'll just keep throwing out every thing I can think of to keep her away.
For now, my banded 6-year old martins are proof there is indeed a ray of hope for my colony.  I think I need to get a bumper sticker that reads, "My Purple Martins Graduated with Honors from GHO Battle School"..... or something.  Ha!