2020 Season Begins!

 The 2020 Season began with 8 owls!  What a great start!  

2020, Master Bander Ken Sobon takes on the Station and the Blog, Pass the Birdbling Please!

In 2017, I (Dawn) retired from directing the owl program and was thrilled when my subpermittee Ken Sobon said he wanted to continue the project. Long term monitoring of a species reveals population trends and is valuable to identify changes over time with our changing climate, prey fluctuations, regional fires, etc. We've learned so much over the 12 years that I ran the station, including, there is so much more to learn. It's all been such an incredible part of my life in Northern California and now, time for a new chapter. I'm sure there will be owls involved!. Ken has put in hours of banding, enhanced the program with nest boxes and technology, and is a competent leader. He has recently received his Master Banding Permit. CONGRATULATIONS! Ken will also be taking over the blog and continue to share season highlights. 

Master Bander and Station Director, Ken Sobon

Passing the Baton, Master Bander and retired Station
Director Dawn Garcia

            

2019, 100 OWLS!!

 A lot happened in the 2019 NSWO season. Below are a few highlights of the season. We banded 100 new owls and captured a bird originally banded in British Columbia! We had some cool mammals in the area including our typical bats, a netted flying squirrel and a ringtail (Bassariscus astutus)!

Licensed banders were Project Director Ken Sobon and assistants Wyatt Hersey and Dawn Garcia. Thank you to our returning seasoned bander Julie Newman and volunteers Mary Muchowski, Jessica Shippin and Tanner Hansen and many new volunteers: Charlie Gianini, Jack Geist,  Megan Cheny, Leslie Saldavar, Melany Scannell, Anton Dressler, and Asher Perla. WOW, thanks to all!

Portrait of a saw-whet banded in 2019

NSWO banded at the BCCER since 2005. Blue represents the number of adult
owls, red represents the number of  young owls (hatched that year).

Our 2019 foreign recovery, a three year old originally banded in 2017
 in Canada. 

Ken shows off the owl from Canada, only our 3rd foreign
recovery since we opened in 2005. 

The elusive ringtail, a super cool mammals 
of the oak woodlands

A NSWO BAND RECOVERY- A FIRST FOR THE BCCER!

At CSU Chico Reserve's we have banded almost 900 owls since we first opened the monitoring station in 2005. This is the very first time another station has recaptured one of the banded owls from our site. And look at the traveling this little lady did~ approximately 800 miles straight line distance! Of course that probably was not her flight itinerary, maybe making stops in Oregon and Washington? You can see by the banding certificate and map below sent to the "finder" by the Bird Banding Laboratory that we at the BCCER site captured the bird as a Hatch Year (she was hatched in 2017) during fall migration.

Information and points where this female HY bird
was banded (blue, 2017) and recaptured (yellow, 2018)

Then, this October 2018, Rocky Point Bird Observatory in Canada, netted her again during fall migration. It's been a full year since her original band date. Where has she been?  We can only guess between point A and B but I assume she flew north in the winter/spring 2017 to breed, maybe somewhere in Canada. Then she flew south through the tip of Vancouver Island at the RPBO. Here her information was input into the BBL's "report a band site" by Rebecca and she received the certificate of appreciation showing the owl's information.

The certificate banders receive from the Bird Banding Lab
when they report a banded bird

Foreign Recoveries (a recapture of another stations bird), are much more common where the NSWO banding stations are denser, like back east and Canada. They are valuable to determine timing, direction and distance of migrating owls, and longevity. Check out the map below for active owl stations across the country

Map of active NSWO banding stations (red dots) in 2010

2018 NSWO MONITORING OFF TO A GREAT START!

Ken and banders Wyatt and Dawn, plus a great group of veteran and seasoned volunteers will be running the NSWO station at the BCCER again, for the 16th season! We had a training for new assistants to show the banding process, the data we collect, and the value of long term monitoring. Ken and Wyatt conducted their first banding on October 8 and were surprised with an evening of 10 new owls! Eight of the owls were hatched in 2018 (HY) and 2 were second year, SY, hatched in 2017.  It appears that it could be another great year for owl reproduction from this population of owls. If you want to learn about the owls, contact Program Director Ken Sobon, ksobon@thermalito.org.

The owls are curious and often look at you before take off.
Photo by Ken Sobon

NSWO CSI; Murder on the BCCER

Banding an owl tells us many things including age, longevity,  movement, residency and death.  In late February, Jon Aull, Outdoor Education Coordinator at the Reserve contacted us about a saw-whet he had found predated, band number 1104-43252.

Predated Saw-whet Owl at the BCCER
Note the band on the right leg. (Jon Aull photo)

I looked it up in our database and found that this individual was banded on October 28, 2017 during fall migration on the Reserve. We could not sex the bird due to overlapping measures of wing chord and mass (84 grams), but we did age it as a hatch year. So this owl did not survive a full year. If a bird makes it out of the nest, the first year becomes the most vulnerable period in their lives. There are predators, disease, and man-made obstacles in the wild, and young birds learn through experiences that they don't often survive.

I think that maybe a great horned owl caught this owl at night and had half a meal, or maybe a mammal plucked the saw-whet from a low perch during the day. I don't believe it was killed by a diurnal raptor like a cooper's hawk, because the owl would have been surrounded by plucked feathers. 

If you find a banded bird contact the bird banding laboratory (BBL) and you will receive information about that bird  AND a certificate of appreciation. Thank you!

BEST YEAR EVER 2017, 162 NEW OWLS!

Fall 2017 migration season kept the BCCER owl banders very busy, and very happy! We had 175 total captures including 162 new owls and 13 same season recaptures. The owls consisted of 121 females, 11 males and 30 of unknown sex. We had a whopping 120 hatch year owls (owls hatched in summer 2017) and 40 owls were two years and older (17 were three+ years!). See the previous post for more details: http://birdbling.blogspot.com/2017/11/one-hundred-and-twenty-nine-owls.html

ONE HUNDRED AND TWENTY NINE OWLS!!!

Yep, that's how many owls we have banded since our first night of owls on October 12, with an opening night of 13 owls! Now on November 3rd, we still have a couple of weeks of migration (October 15-November 15, with sampling on either end). It is our highest number of migrating owls since we have run the station annually in 2005. VERY exciting! The majority >80% have been Hatch Year (HY) owls, hatched sometime this summer in 2017. All these youngsters are easy to age. Here's how. We look at the dorsal side of their wings to see what their molt pattern looks like. And we use descriptions like chocolate to describe the color differences between new and old feathers. We look at the remiges; the primaries (10) and secondaries (13).

Hatch Year, all feathers one age (uniform molt pattern)

Second Year, outer primaries and inner (closest to body) secondaries have been replaced,the new feathers are darker(dark chocolate) and of higher quality then the old,
retained (milk chocolate) feathers. 

After Second Year, (over 2 years old) has three generations of feathers
fresh (dark chocolate), old (milk chocolate) and very old (old milk chocolate!)

And then, there is the magic trick to confirm our age determination. We look at the ventral wing and turn on a black light and like a black light poster, the feathers glow! It's actually a pigment called porphyrin. If you like chemistry, go here to learn more about porphyrins.

Notice the difference in porphyrin glow? As the feather ages, the pigment ages too;
the older feathers don't glow as brightly as the fresh feathers. How old is this bird?

OH, AND THAT SPIDER....

The wolf spider! Volunteer Mary Muchowski found this lady on our way down to check the nets. Guest Dan Roskopf was with us to meet a NSWO, and took the spider's photo. She's a protective mother, carrying tens of babies on her back. Apparently this is rare spider behavior, only wolf spiders do it, so I feel very excited that we got to see her! Watch this video to see a live version of active young wolf spiders: 

Wolf spider mother and hitch-hiking babies, Dan's photo

there is always something interesting in the night.... Come join us and see for yourself!

Dan and Mary with NSWO, Dan's first!

OWLS, BATS AND SPIDERS, OH MY!

Owl season was off and running on October 13, 2017 when program directors Ken and Julie and volunteer Mary, banded a whopping 13 owls!! Since then, we have been out six more nights and have banded 5, 5, 2, 7 and 6 owls, = 38 owls, averaging 6 owls a night. A great surprise, we had one recapture from our Snow Goose Festival event from January 2017, showing migration site fidelity. Recapture information is always valuable.

• 

  NSWO profile. They are amazing tiny predators, and captivate all that meet them!

Lucky guests, meet and release a NSWO

Volunteer Carol Anderson with saw-whet owl.
Volunteers help drive our program, thank you!

All our other owls are new owls without bands and most are hatch year birds, meaning owls were hatched in summer 2017, and it was a great summer for saw-whet owl breeding! We have also captured and released 3 pallid bats, a flying squirrel and a katydid!

OWLETS In a Box and Another Occupant

Ken was able to check the owlet box this week; the chicks look healthy and mom is still roosting in the box with them. Both owlets are losing their down feathers and looking more and more like adults as their contour feathers grow. They were more curious about the camera then mom, who has the adult wisdom to avoid predators, lie flat and be still.

This owlet in the box is still pretty downy.

This owlet is slightly older, showing more contour feathers

The nestling phase is about 35 days so they should fledge between the 3rd week and end of June. We were hoping to put up some cameras around the nest box to watch the parents deliver food and the chicks fledge, but the supporting trees were too far away. We'll have to come up with other ideas.

Meanwhile, last week we found another occupant in nest box #2. We have deduced, based on the list of cavity nesting birds in the area, that it was an ash-throated flycatcher egg. Since there was only one egg and it had ants on it, we determined it was abandoned. This weeks' box check confirmed it, no new eggs, more ants.  Here's how Cornell Lab of Ornithology describes the egg, "creamy white with reddish brown streaks and elongated blotches." Click this link for more information about the ash-throated flycatcher. 

Western Screech OWLET UPDATE and Photo Essay!

#1! Lots of down but some contour feathers appearing

#2 of the two owlets

It was time to band the owlets after peeking into the box last week, I determined they were old enough, ~ 3 weeks to 1 month old and getting ready to "fledge." Typically owls leave the nest cavity and are called "branchers", because that's what they do, sometimes falling clumsily to the ground, climb up a tree, and perch on a branch. Their growing flight feathers are heavy with blood and they beg for food and begin to persistently follow their parents around before they are capable of even moderate flight. I wondered about this being a successful strategy because it seems safer remaining in a protected cavity. But after seeing and smelling the remains of this nest box, I think I figured out why it's best to get out of there (see below!)

At least 3 prey remains in this nestbox

Here is more evidence of the male being a good provider with three different prey remains that might be a deer mouse, vole or gopher and the tiny remains of a pocket mouse or other tiny rodent.

Ken climbs the ladder and hands me the mom for
weighing and checking the band we put on last week.
You can see the plug in the nest hole.

We begin with Ken removing the female from the box (the nest hole is plugged to ensure she doesn't flush out of the nest) and handing her to me. She is held in a bag until the nestlings are banded. As typical for screech owls, she is very calm through this process.The female has a lot invested with two owlets, so would unlikely abandon a nest at this stage. Both owlets were plump at 135-145 grams (the same weight as some adult males).  We banded and weighed them separately, so owlet #1 remained in the bag quietly waiting for the sibling.The mom was also well-fed, weighing in at 190 grams!

One owlet banded and held in a cloth bag until the second owlet is processed

The owlets are returned to the nest box, then mom is returned. We wait about five minutes to remove the plug before leaving the owls safely in their box. I have no doubt the male is roosting somewhere nearby, but we were unable to find him.

OWLS and OWLETS!

Today Ken and I checked the boxes on the Reserve. We were particularly interested in Nest Box #15 (sort of like an address) where we discovered a nesting Western Screech Owl, 37 days ago in April. Today May 27, we saw a mom owl with her two owlets and a nice meal for the chicks, a deer mouse (peromyscus sp.)

A view from above: 3 screech owls and breakfast. Note the larger owlet on the left.
Owl eggs hatch asynchronously, so one will be a little older than the next.

Ken removed the female and lowered her down to me for banding. She remained still and calm through the process.We returned her to the box after taking some measurements and examining her condition.

Here I am taking the wing chord measurement of the owl.
Note the band on her right leg.

Then I looked at her brood patch. Hormones help release breast feathers providing direct heat exchange for incubating eggs and brooding young,until owlets can thermoregulate on their own. This female's brood patch is already getting pin feathers (two dark lines under her bare skin), because the owlet's feathers now keep them warm. By fall her breast will be feathered, which will help keep her warm for the winter months.

The brood patch, well past its use for warming chicks. Because the
chicks now have feathers they no longer need warming by the adult.

Leftover prey shows the male is a good provider. He was likely roosting in a cavity nearby, and maybe observing us. Stay tuned for the rest of the story!

A view with the mom removed. The owlets are about the size
of an adult deer mouse (right corner), and too small to band.

The Cornell Lab of ornithology is a great resource for bird natural history including screech owls. Also click here for a nice overview of owl courtship and reproductive behavior.

OWL IN THE NEST BOX!

Western Screech Owl inside a nest box

Can you see the the owl in the box?  You are looking at the head and back of a Western Screech Owl inside nest box # 15. We believe she is incubating eggs due to her flattened posture and absolute stillness when we peeked the camera into the box. If she is incubating and all goes well, we can expect to see 2-7 nestlings within the next month.

So how did we see her? This winter Ken and crew installed nest boxes to determine potential use of the BCCER as breeding site for Northern Saw-whet owls, a cavity nesting species. To check the nests Ken attached a flexible cable with tiny camera and LED light to a bamboo pole, plugged in to his tablet. He can feed the camera quietly into the cavity entrance, see what is inside on his screen and then take a photo. We have conducted two box checks,

Ken's nest-cam set up. The camera is at the end of the pole
inside box #4. He is viewing the inside of the box on his tablet.

one on March 11 and one on April 19. In March, we found bird feces in two two boxes but no birds were present. We guessed the boxes were used by Northern Flickers roosting in the boxes at night. In April, we found identifying flicker feathers in the same boxes, and then we found the screech owl in a third box, What a fun surprise! Learn more about Western Screech Owls here.

SPRING MIGRATION, what do we know?

As with many of our questions, the answer is.....more study is needed! According to Project Owlnet, spring migration is poorly studied. And so, Ken and the owl monitoring team are making winter/spring efforts more standardized to identify migration timing on the Reserve. So far this year we have seen some new activity near the end of February with 10 new owls so far! Here's what it looks like:
February 25, 2 new owls
February 27, 5 new owls and 1 recap
February 28, 1 recap
March 2, 3 new owls
March 3, 0 owls

Bander Erika Iacona with one of the February 27 owls.

Is this a sign of spring migration? Possible, BUT, this year has been unusual, relative to the past 5 drought years. We have had record rainfalls and snow levels in the Sierra, which may hinder birds from moving to their breeding sites too early.So, we will continue our spring efforts to  enlighten our migration question this year. WAIT FOR IT!

BAT-EATING WESTERN SCREECH OWL?

We know based on aural and/or visual detections that we have at least five species of owls on the Reserve; great horned owl, Northern pygmy owl, Northern saw-whet owl (NSWO, fall through spring?), California spotted owl (winter only), and Western screech owl (WESO). The screech owls are year-round residents and will sometimes come to investigate our NSWO caller, so they get caught in the nets. We have banded 25 WESO over 12 years of monitoring NSWO. Sometimes we are lucky to see them roosting in a cavity during the day, or perching at night. Banders Erika and Ken saw this owl perching in the barn, likely

Western screech owl in the barn at the Reserve
Possibly foraging on bats? He/she appears a little
perturbed at the disruption!

taking advantage of barn mammals. It may have been foraging on the bats that roost there! There happens to be a colony of wintering free-tailed bats, and potentially other bat species, living in the barn. I have seen great horned owls, peregrines, merlins, kestrels and red-tailed hawks capturing bats as they exit their roosts. It was quite an exciting flight dynamic as the predator bursts in a cloud of bats.  The success rate on capturing bats seemed pretty low. What we need to determine if this WESO has a palate for bats, is to find some pellets to identify prey remains.

A Winter Owl's Meal

Ken and team have continued monitoring owls through the winter and have found that three individuals have remained on site since fall. Three others were newly banded this winter and recaptured. It appears the wintering population of saw-whets on the Reserve is pretty good-which indicates that the prey base it sound. And proof is in the owl mass- all have increased since their first banding. Below is an example of this female's weight history, captured and weighed three times.

one wintering NSWO captured and weighed 3 times

01Jan2017 =  90.5 gr

02Feb2017 =  95.6 gr

11Feb2017 = 101.7 gr

NSWO are primarily rodent predators, but are also opportunistic, taking advantage of what's available (birds, insects, etc).From previous pellet analysis conducted by Julie Shaw (see earlier posts in 2010-2013) and visual observations we know Reserve owls eat field mice, deer mice and California voles. One owl even ate rain beetles! Saw-whets will often make two meals out of one prey item and roost with it or cache it for the next meal.

A great web photo of a NSWO with deer mouse prey

ATTENTION SAW-WHET OWLS - Nest Boxes Available!

Ken Sobon and team have installed over 15 nest boxes on the Big Chico Creek Ecological Reserve (BCCER). He is hoping that the boxes will attract saw-whets, perhaps those wintering on the Reserve or moving through in spring, will stay and nest. If a pair does-it would be the first documented saw-whets breeding on site! We haven't done any summer surveys so we can't say they don't breed here. Generally I think the Reserve is too low in elevation (and hot) for Sierra Nevada breeding habitat, but these owls are shown to be nomadic, meaning they will breed where conditions are right (good prey, micro-climate) and don't often return to the same breeding area.

Locations of seven nest boxes on the Reserve. Also see our two banding sites, OWL2 and OWL3. The structures include barn workshop, office and old ranch house.The forests provide cover and good roosting habitat for owls and the meadows are great habitat for foraging for rodents.

You can see the boxes are distributed around, mostly under good canopy cover and near meadows for foraging and all boxes face NE (cooler). Some are on different tree species, some near small drainages, some with a different slope aspect.  It will be really exciting to check these boxes. Other cavity nesters that might find the boxes homey are western screech owl, ash-throated flycatcher, northern flying squirrel, wood rats and???  Monitoring begins in early March. Stay tuned!

This box #8 will be under a fairly dense cavity when the oaks leaf out.
You can see the canopy closure in the aerial google earth photo above
taken in late May.

Let's Get it Started! Nest Box Program for the 2017 NSWO Breeding Season

New project co-director Ken Sobon is moving forward into the breeding season for owls. We don't know if NSWO breed on site, but we have captured them as late as 4 April, likely during spring migration. We have made limited attempts during the late spring, early summer to identify nesting birds, with negative results. BUT this species is opportunistic and considered to be nomadic, nesting where the prey base and other conditions are right, and not necessarily returning to the same nesting area. Habitats on the Reserve could be good for saw-owl breeding in some years.

Ken's nest box building team, hoping to entice saw-whet owls!

Drilling the "cavity" entrance

Ken and his team may be monitoring for years before
actually finding a breeding owl, or it could happen this spring. If he does find a saw-whet it will be the first documented nesting on site. He might also find other cavity nesters using the boxes including Western screech owl, American kestrel, ash-throated flycatcher, northern flying squirrels and ??? Check back to our blog!

Ken installing nest box #5

New Project Directors Ken Sobon and Julie Newman 2017

Welcome Ken and Julie as the Northern saw-whet owl fall monitoring project's new directors. What a great journey it has been and a privilege to pass the project along to these two dedicated volunteers. Ken is the VP for Altacal Audubon Society (our project sponsor) and Julie is a professional environmental scientist. Both have banded and participated with the project for several years.

Ken Sobon, NSWO project Co-director

Julie Newman, NSWO project Co-director

Long-term monitoring of a species is essential to understand population trends and local natural history. Thank you for continuing this important work. Great team!