Sunday, June 30, 2013

June 30

     For those of you who have been following along, welcome to day 112 of the season. For those of you who are new to the blog, welcome to day 112 of the season :)  I have been seriously slacking on blog entries lately. There is just so much going on that by the time I enter data into the excel sheets every night it is after midnight.  I will attempt to give you all a synopsis of where things are at with the project. 
     Up until 10 days ago, there were 19 boxes where I had confirmed the presence of either eggs or young.  At this late point in the breeding cycle it is very unusual to encounter "new" boxes where so called "floaters" ( males/females that arrive very late in the season at boxes with the intent of beginning very late breeding) actually initiate successful breeding. Interestingly enough, within the last ten days I have discovered 2 more boxes where kestrels have just begun egg laying with a third box a strong possibility as well. That would bring the total number of successful boxes up to 22. I have boxes where the young left the box 10 days ago and now also have boxes with 3 eggs in them. That represents a 60-70 day window of breeding activity. That is similar to year's date ranges and has been a totally unexpected finding for this area.  To date there have been 34 nestlings banded with another 15-20 to be done in the next day or two. As pictured above, the nestlings are banded with both a metal federal leg band and colored plastic bands as well. The metal federal band has a unique number stamped into it that identifies every bird. Each nestbox has a unique color band pattern assigned to it that identifies the nestling's natal nestbox.  That unique color pattern is permanently assigned to every successful box. The only way to read the number stamped into the federal band is to recover the bird in your hand. The idea behind color banding is that in the future the color banded birds can be identified at a distance without the need for actually having them in your hand. It ideally increases the reporting of color banded birds in the usual instances where trapping is not possible. In reality, the color bands can be very difficult to detect in the field. It is had been moderately helpful to me in identifying birds not in the hand, but has resulted in no reports by other birders, etc. out on the field who might be seeing these birds. 
     This summer I also have a senior from the University of Connecticut who is doing her honors thesis work based on telemetry that is being carried out on some of the birds in the program. The basis of the telemetry work is to try and determine the post fledging dispersal patterns of the young. We really have no idea where the young disperse to once they leave the natal area.  Since the American kestrel is a threatened species in Connecticut, knowing where their critical stopover points are in migration and which corridors they may be using ( ex. the Connecticut River valley, etc.) when leaving their natal area is important information needed to help make informed decisions to aid in their recovery in the state. To date we have outfitted 4 nestlings with the tiny backpack radios. Our goal is to have 10 nestlings outfitted with radios.  Anything we learn about their movement once they begin leaving the natal area will be more than we know now..which is virtually nothing.  

This picture shows a 27 day old nestling with her radio backpack on. The only part visible is the thin antenna projecting out from the backpack. 

 An important step in the banding process is sexing the nestlings. That is most easily accomplished by examining the color of the primary feathers. The blue/gray coloration of these primary feathers identifies this bird as a male.

The brown coloration of the primaries on this bird identifies her as a female.  If the nestlings are younger than 14 days old it can very difficult to sex them since the primary feathers have not yet begun to emerge at that point. This female is approximately 18 days old. 

     The total number of box visits made by me so far this season is 948. Total miles traveled to date this season= 4,714. 

Thursday, June 20, 2013

June 20

16 day old nestlings

Very fierce falcon wannabe 24 day old nestling

     a full box of 5 nestlings 20-24 days old with prey remains (song sparrow) left in the box by the adults

a close-up of the song sparrow left in the box by the adults

Annie and I with the first nestling this year to be outfitted with a radio transmitter for telemetry purposes

     After a little bit of a lull waiting for the young in the earlier boxes to develop enough to be banded, things are starting to pick up. Twenty-three nestlings have been banded to date. The broods have contained either 4 or 5 nestlings, which is the norm. You can see from the photos that the development of the young progresses very rapidly. The changes in appearance in the nestlings as they develop is remarkable. That is evident when you look at the photos of the nestlings above. The ideal age window for banding is 16-18 days old. If you remember from previous posts, this is calculated by dating forward from the appearance of the first eggs in the box. It is not always an exact science, but it can get you close. There are times when, for many reasons, one can be surprised upon opening the box. What you expect to be 16 day old nestlings looking at you can, in fact, be birds that are barely able to lift their head or birds that are nearly ready to jump out and join the big, bad world. Speaking of which...............I don't think I have mentioned this in other posts, but the expected mortality of first year birds is as high as 80%. Imagine thinking about the fact that, after all this work since March 8, probably only 1 out of every 5 nestlings will survive to breed next year. It is not something I tend to dwell on much. From the photos it is also obvious that the youngsters need a little help in the keeping their bedroom clean department. Actually, the center area of the box where they spend most of their time huddled is actually quite clean. Like many nesting raptors, these young are programmed from birth to back up to the outside edges of the nestbox and squirt their feces in an outward direction away from the center of the nest. This results in having the inside walls of active nestboxes completely covered with whitewash. One of my favorite jobs every March is opening the boxes to scrape off all the whitewash of the walls of the boxes. Ina howling, freezing wind it doesn't get any better than that. 
The prey delivered to the young consists mostly of insects, with the occasional meadow vole or small songbird tossed in for good measure. In my experience, it is the males who tend to deliver the largest prey items to the box. They don't show up often.......maybe once for every 40-50 visits by the female, but they deliver the goods when they do. The last picture today shows Annie and myself with a 28 day old male who has been outfitted with a radio transmitter for telemetry purposes. I don't have the time to discuss this topic now, but will cover the telemetry aspect of our work this year in a future post. I'm hoping to get to that post written fairly soon so I don't get chastised in Latin again for not posting more frequently :)         

Friday, June 7, 2013

June 7

An explanation of incubation timing, etc.

     Our vendor fair was a total washout today so we left to come early. I will take this opportunity to follow up on yesterday's post.  The typical clutch of kestrel eggs contains 4 or 5 eggs. Once the female begins laying she will lay, on average, one egg every other day until she is done. Once all the eggs are laid, it will be 30 days until the eggs hatch and then 30 more days for the young to fledge. This easy math makes the calculations for when banding should occur, etc. pretty easy to figure out.  The young should ideally be banded somewhere between the ages of 15-18 days old. At that age their lower leg bones are adult size so there are no concerns about their legs growing larger and having the bands becoming overly tight. In addition, beyond the age of 14 days old the primary wing feathers and other areas are developed enough to be able to accurately sex the birds. 
     Now, let's hit the rewind button a bit. The reason I spent so much time going into the nestboxes during April and early May was two-fold. First, it was necessary to keep the starlings out. Secondly, I was waiting to see the first eggs in the boxes so that I could then calculate the best day to go into the box to band the young. For example, let's say that on April 16th I went into a box and found 2 eggs. At that point I would add 2 days for every additional egg that would be laid up to a maximum of 5 eggs. That takes us to April 22nd. I would then add 30 days to bring us the the hatching date. That would be  May 22nd. I would then add 5 days to bring the young up to an assumed age of 5 days old. So after waiting 41 days from the time I found the first two eggs, I would go up into the box. At that point I would be able to fine tune the exact final banding date, wait for that date and band the young. The math is not as exact as I portray it to be in this post. Sometimes egg laying can be delayed, incubation times can vary, etc. but it's usually pretty close. If you band them too young, you may not be able to determine the gender of the bird. If you band them too old, you run the risk of having them leave the box too early and prematurely fledge. That puts them at very high risk.
     I hope this rather long-winded explanation helps others to understand the level of vigilance that is required if one is to to study and truly understand the dynamics of American kestrel populations. It is important to note that this is day 89 of my kestrel season and there is still a long way to go. Fascinating stuff.  In the next 10 days I will be doing pre-banding visits at many, many boxes. I will keep you posted on what I find.  

Thursday, June 6, 2013

June 6, 2103

First young birds of the year :)

     Hello everybody- I'm sorry for the absence of recent posts, but this is a very busy season for my bird photography business.  My wife and I are leaving for vendor fairs that will run from tomorrow morning (Fri.) until Sunday evening. That, coupled with continuing long days in the field, have made it difficult for me to find the time for posting. I have confirmed eggs in 22 boxes. There may be another box or two that end up having eggs in them, but at this point in the season what you have now is probably what you will end up with. The starlings have been absolutely swarming some of the boxes that I had high hopes for so, for the first time since I have been running this project, I am actually closing those boxes up for the season. Above is a picture from yesterday that shows the young that were in the first box that had eggs this year. The typical clutch size for kestrels is 4-5 eggs.  There are four healthy young in this box, approximately 8-10 days old. If you look closely at the right front corner of the box, you will see an egg in the box that is obviously infertile. The adults have long since stopped incubation. 
     Timing is everything. I am now conducting what I call pre-banding box visits. The young should ideally be banded between the ages of 14-18 days old. At those ages their legs have reached adult size and the primary feathers have developed fully enough so that the birds can be accurately sexed. The question is- How do you know when they are at that age without being able to see them?  The only way to know is to go up into the box when you predict that they are 5-10 days old, have a look and then fine tune your final banding date from that. I will give a more detailed explanation of incubation/hatching/banding timing in my next post. I've got to run now, but there will be more posts coming as soon as I can find the time.