Current Postings

See Archived Postings

June 25, 2009 — July 1, 2009

One of the topics mentioned last week was how the LSLBO banded a wonderful looking female black-throated green warbler during MAPS banding. It was worthy to mention because only three or four pairs breed within our banding sites and catching just one of those breeders is a rare occurrence. This past MAPS round we managed something that has not been done at the LSLBO for many years, we banded a male black-throated green warbler in breeding plumage. Only six other males wearing their breeding colours have been banded at the LSLBO in the past 15 years. Like most wood-warbler species, black-throated green warblers have sexually dimorphic plumages, meaning the males are more brightly coloured than the females. I had always thought the females were gorgeous and wondered what banding a male would be like. After nine years of bird banding it was great to finally have the chance for a close look at one of these stunning birds.

The Canada Warbler Project is coming to an end as the nesting season winds down. Over the past few weeks we located six Canada warbler nests within our study site. These nests were passively monitored with video equipment to document nesting behaviour and nest success rates. Two of the nests failed at an early stage. A predator grabbed the eggs only a few days after they were laid. Two of the nests successfully fledged five young apiece. The outcome of the final two nests will be determined over the next few days. The young need a little more time to finish developing before they are at the stage where they can leave the nest. The Canada Warbler Project may evolve into something much larger over the next few years. Canada warblers were recently designated as threatened by the Committee on the Status of Endangered Wildlife in Canada (COSEWIC) because of steady population declines throughout their breeding range over the past 30 years. The data we have collected from these nests may provide information that will help identify population threats and possibly assist with future recovery plans.

It's the time of year that baby birds are leaving their nests and there is something very important to keep in mind. Nestlings from many songbird species will fledge from their nests before their flight feathers are fully grown in, so they are incapable of flight. This may seem strange, but it makes sense. An entire brood is vulnerable to be wiped out by a predator, like in the case of our first two Canada warbler nests. When the young are scattered in the forest there is an increased chance that some will survive. Parents will continue to feed their chicks out of the nest until they are able to fly and feed on their own. If you see a young bird on the ground the best thing to do is simply leave it alone. One of the parents is close by. Remember, these birds have come a long way just to raise young; they will not abandon them easily.

June 18, 2009 — June 24, 2009

We completed the second round of MAPS banding at the LSLBO and although the banding wasn’t that busy, it clearly gave an impression that there will be a major Tennessee warbler fall migration. There were breeding Tennessee warblers everywhere. A third of the birds we banded were breeding Tennessee warblers. These prolific warblers are going to raise a lot of young, which have a good chance of flooding our nets when they begin their fall migration. That’s my prediction for the fall. It should be noted that my predictions have been know to be brutally wrong in the past. Some species we normally see in large numbers during MAPS banding have been scarce so far. For example, American redstarts and Swainson’s thrush captures have been very low. That being said, we have only completed two of the six rounds of banding. During the next round we should start to catch fledglings. Many of the nests we have found (most of which were Tennessee warbler nests) have hatched and the parents were madly feeding their young. It won’t be long until the young are ready to leave their nests and fly on their own. One of the more visually stunning birds we banded was our first black-throated green warbler of the year. We do not band very many black-throated green warblers during MAPS, so this bird was a real treat.

I have been asked a few times if there have been any changes in bird migration due to climate change. My answer has always been “I don’t know.” An opportunity has come about that will give me a chance to explore the LSLBO data to see if there are any shifts in migratory timing. The next step would investigate if the shifts are correlated with increasing spring temperatures. After reading some literature to prepare for this task, I was blown away by the complexity of this topic. Studies have shown that some species have been arriving on the breeding grounds, in varying degrees, earlier and earlier over the past few decades. Average warmer spring temperatures were one of the causes. A warmer spring means increased food availability as the plants and insects emerge earlier. But the issue became more clouded when some species showed later spring arrival dates. A migratory bird’s life cycle is complex and spans across an entire continent. Changes in climatic conditions on the wintering grounds, along migration routes, and on the breeding grounds will affect some part of a bird’s life cycle and can result in changes in migratory patterns. Changes in migratory patterns can result in changes in breeding patterns, distribution, and abundances. The consequences of these changes are not fully understood. This will be a very interesting project and I get the feeling LSLBO’s data is not going to result in a specific answer; it’s going lead to a lot more questions.

June 11, 2009 — June 17, 2009

A full month separates spring and fall migration at the LSLBO. During that month the banding staff works on two projects which focuses on breeding birds. The first project is MAPS. Banding at MAPS stations is fairly quiet for the first couple of weeks before the young fledge from their nests. After the first visit to the four stations, only 38 birds were banded. Although this seems like a small number of birds for the amount of effort it takes to run the stations, we are gathering important information about survivorship, return rates, and productivity of our breeding birds. MAPS is where we collect our most interesting recapture records. We recaptured a male American redstart that was originally banded at the LSLBO in 2004. That makes this bird six years old. That may not seem that old, but consider that this bird only weighs 9 grams and has flown well over 50,000 km in its lifetime. To make it a little more amazing, this bird has likely returned to the same patch of forest every summer to breed.

The second project is the Canada Warbler Project. This project started up in 2004 and is an intensive study on the breeding ecology of Canada warblers. Canada warblers are a poorly studied species. The high densities that breed around the LSLBO banding station makes it a great spot to study these birds to fill in some of the information gaps. Our goal is to mark individuals with colour coded legs bands to identify their breeding territories, locate nest sites, and monitor the nests. The downside to this project is that it is labour intensive and finding time between our other projects is tough. But considering that we have located 12 breeding pairs and three nests, we are doing very well.

The key to Canada warbler nest searching is finding a female. The males are of no real help, they are more interested in singing on the far side of their territory and fighting off intruders. The nests we have located so far were easy because the females were busy constructing their nests. This means frequent visits with nesting material. But once the nests are build, which takes about three days, the search becomes absurdly difficult. We have to sit and wait for the female to leave the nest to feed. Once incubation begins, the females will leave the nest about once an hour. She will give a few soft chips to advertise she is off the nest and will return a few minutes later. Canada warblers nest on the ground in areas with thick vegetation. This makes it particularly difficult to spot where she lands after she is done feeding. It takes a few feedings before we can pinpoint the nest site. We have tried the “get down on hands and knees and search” approach, but nests can be in any hollow on the forest floor. Its mind-boggling how many hollows exist on the forest floor.