Saturday, December 21, 2013

A close up look at the Gray Catbird - Wascana MAPS Part 2

In part two of this series I want to focus on some of the band returns we have had with the Gray Catbird (GRCA) at the Wascana MAPS site, in Regina, Saskatchewan.  Between 2010 to 2013, we have banded 72 adult GRCAs and recaptured 14 of those individuals (19%) , with some individuals being recaptured in multiple years. 

The figure below shows the number of adults captured each year and within that the proportion of newly banded adults and birds who had returned to Wascana Marsh with a band already on its leg.  Of course, because 2010 was our first year of banding, we did not have any previously banded birds to recapture.  In each year, returning GRCA's make up 28 to 42% of the total number of adults captured.  These are some of the highest return rates we see for all of the species we band at this site, except for perhaps Yellow Warblers. 
Click on image to see a clearer graph
Interestingly, we can look at what the survival rate and return rate for GRCA's is from other MAPS stations thanks to the Institute of Bird Populations.  In our continental zone (North-central) there are 36 different MAPS stations that have banded 3940 GRCA between 1992-2006.  772 GRCA returned in subsequent years.  Based on this, the IBP is able to calculate that adult GRCA's in our zone have a 50% chance of surviving and returning to the same areas they bred in the year before.  Remember that this is an estimate as to whether the bird has survived and returned to breed in the same area, it is not a 50% chance that we will actually recapture it that year.  The IBP website does calculate recapture probabilities which for GRCA's is 48.5% given it has survived and returned to the same area.  So ultimately this means that the bird has a 50% chance of survival, then we have a 48% chance of catching it, so we can expect to recapture about 24% of the birds captured in the previous year...  You can check out the IBP website and find these stats for many other bird species.
If we look at our recapture rates, in 2011 we recaptured 22% of the adult GRCAs that were banded in 2010, in 2012 we recaptured 46% of the adult GRCAs captured in 2011 and in 2013 we recaptured 19% of the of the GRCAs captured in 2012.  Recapture rates in 2011 and 2013 are comparable to the expected recapture rates, but in 2012 the recapture rate was significantly higher.
Gray Catbird with a band on its leg
The actual birds we have recaptured over the years have been interesting as well.  In 2011, we recaptured 3 individual GRCAs that were originally banded in 2010 (a total of 5 were recaptured this year).  These were 2 males and 1 female.  Amazingly we recaptured all three of these same birds again in 2011!  I think it is so fascinating to think that these birds that weigh 35-40 grams will breed in the Habitat Conservation Area, fly south for the winter hundreds of kilometers away along gulf of Mexico, and then come back to exactly the same area the next spring (sometimes being captured in the same net as the year prior!) and doing that for 3 years in a row!
We had 2 more birds return to Wascana Marsh being banded in 2011 and then recaptured in 2012 and in 2013!  Amazing little birds!

Juvenile Gray Catbird
Another fascinating component to our returns of Gray Catbirds, has been the juvenile GRCAs who have returned to the HCA.  In each year, 2011, 2012, and 2013 we have recaptured a single GRCA that was banded the year before as a juvenile bird (~4% of all juveniles banded; juvenile bird meaning it was hatched that year).  All three of these returning juveniles have been males that we are able to determine once they return (as a juvenile we are not able to determine the sex of GRCAs).  While this is a very low return rate of juvenile catbirds (we've banded 74), it is interesting that only males have returned.  This suggests that females disperse from their natal ground, while males may return to breed where they were raised.  Remember too that juveniles often have a significantly lower survival rate then adults.  So the 50% survival rate we discussed above does not apply to juveniles in their first year. 
The Birds of North America Gray Catbird account has limited information on return rates of juvenile GRCA.  It does not give information about sex differences in returns to the natal ground.  Lehnen and Rodewald (2009) found a return rate of only 3 juvenile GRCA out of 304 young banded (1.1%), in Ohio, but did not make any note of the sex of the returning birds. 
Overall, the Wascana Monitoring Avian Productivity and Survivorship (MAPS) station is providing some really interesting information about Gray Catbirds and many other species!  This information will be vital to help conserve Wascana Marsh in the future and promote this space as a very important area for birds! 
Literature Cited
Lehnen, S. E. and A. D. Rodewald. 2009. Dispersal, interpatch movements, and survival in a shrubland breeding bird community. Journal of Field Ornithology 80(3):242-252.
Smith, Robert J., Margret I. Hatch, David A. Cimprich and Frank R. Moore. 2011. Gray Catbird (Dumetella carolinensis), The Birds of North America Online (A. Poole, Ed.). Ithaca: Cornell Lab of Ornithology; Retrieved from the Birds of North America Online:

Friday, December 20, 2013

A close up look at the Gray Catbird - Wascana MAPS Part 1

While the Gray Catbird (GRCA) may not be the most flashy bird that we catch at Wascana MAPS, it is definitely one of the most interesting in terms of what we are learning about this species.  Overall it is the 5th most common bird we capture.  Between 2010 to 2013, 126 GRCA were banded, 72 of those were adults, while 74 were juveniles.

The Gray Catbird is a gray bird, that gives a "meow" like call; hence the name... It has a dark gray crown and rusty undertail coverts, as seen in the two photos below.
Adult Gray Catbird
Rusty undertail coverts on an adult Gray Catbird
Over the last 4 years, the Gray Catbird's productivity has stayed relatively even as seen in the figure below.  This means that roughly the number of juvenile birds that we catch each year, stays proportionally close to the number of adults captured in that same year, with some small fluctuations.  In some of the other species we band, we see large fluctuations in juveniles captured, which is not what we see with GRCA.  Therefore, from this limited data set, these data suggest that the GRCA population is not at this time, significantly increasing or decreasing, and that productivity seems to be fairly consistent at this location.  This is not to say that productivity is good or bad per se, as this is not a comparison to other sites, but simply that it is consistent at our site between years.
Click on the graph to see a clearer image.
Another interesting component to look at is how Gray Catbirds utilize the habitat within Wascana Marsh.  This map shows the net configuration that we use at the Wascana MAPS station.  For a photograph of each of the nets and the surrounding vegetation structure, check out Wascana Centre's website.
We can graph where the Gray Catbirds from 2010-2013 have been captured.  In the figure below, it is clear that Net 2 catches the majority of GRCA.  If we were to break this down greater, you would see that this is the location where we catch a high proportion of young GRCA that are moving along the marsh edge.  Net 2, is in general, our most productivity net, with approx. 25% of the total number of birds we capture each season coming out of that net.  It seems to be a narrow corridor that many of the birds travel along.  Although in the last two years, beavers have changed some of the willow structure around the net, so its capture rate has decreased. 
The overall trend that can be observed when matched with the map, is that GRCAs utilize the marsh edge when there are willows present, but not where there is just cattails and bulrush (net 6 and 7).  They also use the caragana and tree rows inland as well.  We have found GRCAs nesting along the marsh edge (near net 4) as well as inland (near net 8 & 9). 
Part 2 of this post, will focus on the recaptures and returns of the Gray Catbird at the Wascana MAPS station.

Thursday, December 19, 2013

Wascana MAPS station completes 4th season!

2013 was the 4th season of the Wascana Monitoring Avian Productivity and Survivorship (MAPS) station and what a season it was.  We again saw an overall increase in the total number of birds we captured, with 630 new birds of 35 different species, being banded in just 6 days!  This is almost double the number of birds we banded in our first season in 2010.
I just figured out I can't actually upload files on the blog here, so will have get creative as to how I get all the information on here, but I have copied in the results of our 4 years of MAPS banding below.  I have been amazed by the sheer numbers of birds we have captured - it definitely has exceeded my expectations when we first decided to try this project at this site.  In total we have captured and banded 45 different species!  What amazing biodiversity can be found in the Habitat Conservation Area, within Wascana Marsh!
Baltimore Oriole
The Wascana MAPS site is located in Wascana Centre, inside the Habitat Conservation Area.  Here we follow the MAPS protocol set out by the Institute of Bird Populations.  We use 10 mists spread throughout the area in various habitat types, including cattail marsh, willow edge, and caragana and tree rows.  The nets are set up in the exact same spots each year and are opened 6 days each season, evenly distributed between June 10th until August 10.  We start at dawn, which varies from 4:45 am in June, to 5:20 am in August, and keep the nets open for 6 hours.
Nelson's Sparrow
We rely heavily on a great team of volunteers without whom this project would not be successful! A huge thank you to all of you. 
A few highlights from 2013 included a few interesting recaptured birds (birds we banded in previous years), including a Yellow Warbler which was the first Yellow Warbler we banded in 2010 for MAPS.  Another highlight was catching a juvenile Sedge Wren and adult Black-billed Cuckoo!  I have since learned from the Bird Banding Office, that was the first ever Sedge Wren banded in Saskatchewan and the Black-billed Cuckoo was only the 3rd banded in SK! 
Black-billed Cuckoo
I will post more information specifically about some of the recaps soon. 

Here are the total number of birds banded as part of the Wascana MAPS program.  Click on the table to enlarge it, so you can see the Total column.

Sunday, December 15, 2013

Our slowest Northern Saw-whet Owl season in 7 years!

Well this was a bit of a bust of a year for us, in terms of Northern Saw-whet Owl banding!  In total we banded only 45 saw-whets in 20 nights of banding, between September 20 to October 20.  Compared to our 6 year average (2006-2011) of 131 owls/season, this is significantly lower.  We typically stop banding around the end of October, but poor weather prevented us from opening after October 20! 
One neat bird was a recap by my sub-permit, Adam Crosby, captured on October 23, 2013, while I was unable to man the banding station.  The bird was wearing a band that had been placed on its leg at White-fish Point Bird Observatory on March 20, 2012 as a third year (TY) bird (in other words, it hatched in 2010)!  White-fish Point Bird Observatory is 11 mi north of Paradise, Michigan.

As you can see this is quite the distance between our two sites!  Our banding station, where we captured this owl is the green dot, while White-fish Point Bird Observatory is the red dot.  It is important to remember that this is not a direct band encounter.  The bird was banded at WPBO in spring 2012, bred somewhere in 2012, migrated south in the fall 2012, returned somewhere north in 2013 to breed and then passed through our area during the fall of 2013.  There is substantial evidence to suggest that saw-whets are fairly nomadic in terms of where they breed each year and this band recovery is somewhat suggestive of that idea.  In other words, the bird could have nested in northern Ontario in 2012, and then bred in northern Saskatchewan in 2013, but we don't know.  Based on a number of recaptures, we currently believe that saw-whets migrate in a south-east direction when moving through the prairies in Canada.  While these kind of encounters are really exciting, they end up generating more questions then they sometimes answer!

You can check out White-fish Point Bird Observatory's website here