Tuesday, April 19, 2011

April 19 - Spring Migration Monitoring

Our Spring Migration Monitoring program wrapped up on April 14, after three exciting weeks watching spring unfold. The program was very successful documenting the arrival dates and migratory movements for several species. Exciting moments included catching two Northern Saw-whet Owls on the first net round, hearing a Upland Sandpiper flyover, and catching over 130 birds on April 12.

Migration was slow over the first week, with Song Sparrows slowly building in numbers and waves of Tree and Violet-green Swallows passing through. Northern Shrikes were seen throughout the first week, but it appeared that this involved new birds arriving every few days. A few more of the wintering Yellow-rumped Warblers were banded and others recaptured, overlapping with the arrival of spring migrants.

The second week was showed a definite increase in the number of birds around. A number of Red-winged Blackbirds were caught this week, which seemed unusual as they had been around since the end of January, but had stayed largely in the marsh. Most often it was a mixed flock of females and males, perhaps caused by males pursuing females as the prospect for potential mates. The first interesting bird during this period was a Northern Saw-whet Owl caught on April 1st, but a Northwestern Crow captured on April 3rd was the first for the station and surprized all who were present. April 5th saw a fall-out of Violet-green Swallows with over 50 banded that day.

The third week of monitoring saw migration really pick up with the first arrivals of Caspian Tern on the 7th, N. Rough-winged Swallow on the 8th, Orange-crowned Warblers on the 11th, Common Yellowthroats on the 13th, and Yellow-headed Blackbird on the 8th. Large numbers of Violet-green Swallows and Audubon's Warblers were banded during this period, especially over the 13-15th. Another N. Saw-whet Owl was caught on 12th, which is quite intriguing, raising the possibility that a spring movement may occur in early April along the coast. The most interesting bird was a flyover Upland Sandpiper on April 12th, which was the first spring record for the Vancouver area.

Overall, 433 birds were banded and 205 were recaptured of 26 species. Many days of wind and rain resulted in reduced net hours and banding only occurring on 16 days. The species totals for the birds banded are listed below:

N. Saw-whet Owl2
Downy Woodpecker12
Rufous Hummingbird12
Tree Swallow24
Violet-green Swallow14311
N. Rough-winged Swallow3
Barn Swallow1
Northern Shrike1
Marsh Wren88
Pacific Wren11
Black-capped Chickadee310
Northwestern Crow1
Ruby-crowned Kinglet1013
Golden-crowned Kinglet3
American Robin541
Orange-crowned Warbler51
Audubon's Warbler63121
Myrtle Warbler42
Unk. Yellow-rumped Warbler41
Common Yellowthroat2
Spotted Towhee213
Song Sparrow61662
Lincoln's Sparrow871
Fox Sparrow1154
Golden-crowned Sparrow17
Oregon Junco5
Red-winged Blackbird502
House Finch1
American Goldfinch101

A big thank you goes out to all of our volunteers for helping complete our program. We are now taking a bit of a break, but will be starting our Breeding Bird Monitoring program in late May, so stay tuned for updates.

Friday, April 1, 2011

March 25-April 1 - Spring Migration Monitoring

Spring Migration Monitoring has begun and we are excited to be outside every day experiencing spring migration. This is our pilot spring season, and with no other observatories in British Columbia conducting a spring monitoring program, this makes our program especially unique and informative.

As noted in our previous entry the first few spring migrants arrived at the end of the our Winter Songbird Monitoring program. By the time our spring program began on March 25th, plenty more migrants and breeding birds had arrived. Every morning we are now serenaded with the sounds of bird songs, heralding the arrival spring. Not to be outdone the local population of Pacific Chorus Frogs are now beginning to call in earnest as well. The weather, as to be expected at this time of year, has not always cooperated with our banding efforts and we have not been able to band every day. But rain or shine our daily census walk has also been able to track the arrival of spring, especially for species that usually avoid our nets.

Flocks of both Tree and Violet-green Swallows have been seen daily, with 160 Violet-green Swallows on April 1st the largest to date. Hummingbirds have been absent since their first arrival on the 17th, but a Rufous Hummingbird was observed on the 1st. Our most notable catch so far this season has been a Northern Saw-whet Owl. There are no records for Iona Island in the spring, and only four in total for the area, so this bird was truly a surprize.

Many people this winter have watched and photographed a adult Northern Shrike around Iona Island, principally in the area west of the outer ponds. This bird has not been seen for at least a week or two now, but a new second-year bird has replaced it. The bird had tempted us for a few days, flying near our nets and even getting out of one once. But on the 29th it was banded and it has remained in the area since then.

One sure sign of spring has been the arrival of Yellow-rumped Warblers. The wintering population of Myrtle and at least one hybrid Yellow-rumped Warblers have been augmented with at least 5-10 newly arrived Audubon's Warblers. Myrtle and Audubon's Warblers are fairly easy to tell apart, with the most obvious field marks being a white throat and supercilium in the Myrtle and yellow throat and no supercilium in the Audubon's. Hybrids between the two can vary in their plumage, but are usually typified by some yellow in the throat and an indistinct whitish supercilium. The photos below illustrate Audubon's, hybrid and Myrtle Warblers.

Most of the other newly arrived birds have been Lincoln's and Song Sparrows. Only a few of the former have been noted so far, with the first on March 29th. Song Sparrows have really begun passing through with many, mostly males, seen and heard on a daily basis. The first American Goldfinches were noted on March 30th, and increasing numbers of Brown-headed Cowbirds and Brewer's Blackbirds have also been seen. At least one Western Meadowlark is still around and was seen on the 1st.

Orange-crowned Warblers and White-crowned Sparrows have begun arriving in Oregon, it will now only be a few more days before we will begin seeing them here. Spring is here and it will be exciting to see what birds will arrive over the next week!

Thursday, March 17, 2011

March 16, 17 - Winter Songbird Monitoring

Our Winter Songbird Monitoring program has finally come to a close, and it has been an exciting and amazingly successful pilot season. In total we banded 279 birds and recaptured 361 birds of 23 species. A full report will be coming shortly.

All of the winter residents are still around, but over these last two days of monitoring we have have been seeing and banding our first definite spring migrants. We originally defined mid-March as being the end point for our winter monitoring program and it seems to be well chosen. The winter residents will likely stay until mid to late-April. We will still continue monitoring these birds through re-sighting colour-banded birds and through birds detected during our Spring Monitoring Monitoring program.

It has been difficult to predict where the birds may be focusing their activity, but the area between the west side of the woodlot to the wetland has seen most of it lately. Part of this has been the kinglets, chickadees, and warblers using the willows which are starting to bud-out now. But even most of the sparrows have been in this area, feeding largely on the new shoots of grasses and other small plants. Spotted Towhees are also now on territory, and males are frequently seen on the tops of shrubs singing heartily, which has made re-sighting colour-banded birds a lot easier.

It is difficult to choose the favourite banded birds of the period, as the new spring migrants are nice to see again, but we have also had some interesting recaptures as well.

Two alternate plumaged male Audubon's Warblers (one on each day) were certainly a treat to see in the hand after a winter of mostly sparrows. There have been a few Audubon's and Myrtle Warblers around the banding area all winter. These were still in basic plumage when they were last seen, and the few that were caught had not started their spring pre-alternate molt. So these birds were true spring migrants. Another sure sign of spring was the first Rufous Hummingbird of the year on the 17th, an after second-year female, and a male was also heard on the same day. Marsh Wrens have been found at Iona Island all winter, but they always appeared to be few and far between, with only banded one up until the 16/17th. However, we have now banded six, all spring migrants, over the last two days. Several Golden and Ruby-crowned Kinglets, Song Sparrows, Fox Sparrows and Spotted Towhees were also banded recently, but it's difficult to say how many of these are spring migrants versus winter residents.

The recapture highlight from this period was a female Red-shafted Flicker that was originally banded on Dec 13, 2010. Also we managed to catch several Spotted Towhees, Song and Fox Sparrows that were originally banded in November, but have not been seen since. It is interesting that a number of them waited until mid-March to show up again. Perhaps they are starting to become restless before migration and are moving around Iona Island a bit more.

Other birds of note seen around Iona Island included 10-20 Violet-green Swallows, two male Tree Swallows fighting over a nest-box (a sure sign of spring!), at least three Virginia Rails calling from the wetland ponds, the wintering American Bittern, and a few Canvasback.

This concludes our Winter Songbird Monitoring season, a big thank you goes out to all of our volunteers! Stay tuned for updates from our Spring Migration Monitoring program starting on March 25. If you are interested in volunteering, send an email to ionaislandbirds@gmail.com.

Monday, March 7, 2011

March 4 & 7, 2011 - Winter Songbird Monitoring

As our Winter Songbird Monitoring program is nearing the end, the first migrants are beginning to arrive. The weather over the last month has been colder than normal, and the arrival of the earliest migrants, Tree and Violet-green Swallows and Rufous Hummingbirds are about a week or two behind. While monitoring on March 4 did not yield any clear-cut migrants, March 7th had the first Violet-green and Tree Swallows of the season flying around the outer ponds. A few other early migrants were also present, including several species of waterfowl, Killdeer, Golden-crowned Kinglets, Spotted Towhees and Song Sparrows. These are the first trickle of migrants, likely to start increasing later on this month. Willow buds have started opening up and with the warmer temperatures predicted over the next few days it is likely that leaf out will start. Also, get out your hummingbird feeders! With Rufous Hummingbirds present up to the Columbia River it is likely that in less than a week we'll be seeing them back in southwestern BC.

Banding on the 4th appeared spring-like with three Myrtle Warblers caught, although two were the birds caught in recent weeks. Another one of the Golden-crowned Sparrows wintering around the woodlot was captured and colour-banded with all yellow bands.

There also were three interesting sparrow recaptures in the last two days of monitoring, a Song Sparrow banded last April, a Lincoln's Sparrow banded last May and a Spotted Towhee banded last June. The interesting part is where these birds may have gone in the time between banding and recapture. The Song Sparrow and Spotted Towhees were both males with cloacal protuberances, indicating they were breeding locally. So these birds had likely setup territories near the banding area, and may have been roaming about recently getting ready to setup territories for this year. The Lincoln's Sparrow was a bit more interesting. It was originally banded on May 4, 2010 and was thought to be a migrant due to its high levels of fat and its capture during the height of their migration. Recatching it in early March means it has likely spent the winter here, as this is about a month before migration starts. But it raises the possibility that the bird may have been a lingering winter resident, as winter residents have greater site fidelity than migrants. Birds like this make our work interesting and make you rethink about how birds may be using the area.

Wednesday, February 23, 2011

February 21 - Winter Songbird Monitoring

As we inch closer to spring, early breeding birds are busy singing and establishing territories, while later breeding birds have been concentrating in areas of food. Black-capped Chickadees and Marsh Wrens have become more territorial over the last week, with males actively patrolling territories and chasing away other males. American Robins, Song Sparrows, Bewick's and Pacific Wrens have all been heard singing more frequently than before. Grasses and other herbaceous plants along the paths have been greening up and providing food for Golden-crowned and Song Sparrows. The bud's on the willows along the west side of the woodlot have been increasing in size and insects have been congregating in this area as well. Yellow-rumped Warblers, kinglets, and chickadees have all been spending more time in this area presumably to take advantage of increased food availability here.

We managed to catch our second Myrtle Warbler in as many days of monitoring, this bird was a second-year male. The usual mix of both kinglets, chickadees, Spotted Towhees, Fox and Song Sparrows were present, the only 'different' birds were a Pacific Wren recaptured that was originally banded in November and a bright looking American Robin. Other birds of note are the same birds that have been seen all winter, including several Virginia Rails and the American Bittern.

It has been interesting comparing the variation in Fox Sparrows that have been caught at IIBO this winter, with most from the Sooty Fox Sparrow group, but several from the Red Fox Sparrow group as well. We managed to catch two this time that had characteristics of Red Fox Sparrows, such as white tipping to their greater and median coverts and a very rufous colour, but they did not have well defined reddish streaking on their backs. These are likely hybrids between the two groups, possibly from north-central BC, although without genetic testing we will never know. Compare the following photos of the two birds with a more typical Sooty Fox Sparrow.

Nearby at the Vancouver International Airport, a program has been started this winter to capture, tag, and relocate raptors to try and reduce the number of airline strikes, benefiting both raptors and travelers. To get to Iona Island you must pass by the airport and so it is worthwhile to check any Red-tailed or Rough-legged Hawks that you see for patagial (wing) tags. These tags will have a letter and a number to individually identify a bird. The bird below with tag C7 is a Harlan's Hawk (a subspecies of Red-tailed Hawk) that was banded in late January and relocated, but it has subsequently returned to the airport.

Thursday, February 17, 2011

February 13 - Winter Songbird Monitoring

There are not too many places in Canada where you have the opportunity to see, let alone band warblers in winter. Yellow-rumped and Townsend's Warblers regularly winter in small numbers in the Lower Mainland and on Vancouver Island. Wintering locations are most likely limited by temperature and food supply. Townsend's Warblers have been found to use backyard suet feeders, however Yellow-rumped Warblers feed on a more natural mix of insects and berries. As a result Yellow-rumps are found more frequently found in coastal areas, where temperatures are more moderate and insects can usually be found throughout the winter. Iona Island is one of the few locations where Yellow-rumps have been found reliably in winter. This is likely because of the moderating influence of the ocean and the relative abundance of flying insects around both the sewage lagoons and wetlands.

This winter up to eight have been found at Iona and all look to be adult males, with an equal split of Myrtle and Audubon's subspecies. At least one or two have been teasing us all winter by flying just above the nets. Recently, though, the entire flock has been spending more time near the nets in the willows at the edge of the woodlot. Possibly as a result of this, at our last monitoring session we finally caught one!

The bird was an after second-year male Myrtle Warbler. It will be interesting to see now that the flock is spending more time around the nets if more will be caught, and if they will return next year. Other interesting birds around included a recapture Varied Thrush (originally banded in late November), a Spotted Towhee (last seen in April), and a Cackling Goose in the sewage lagoons.

Thursday, February 10, 2011

February 8 - Winter Songbird Monitoring

Spring has sprung! ...or at least it has started. The Red-winged Blackbirds around the wetlands have been a little vocal over the winter, but this time they were in full song and defending territories. Canada Geese have also gotten into the act, by pairing off and becoming more aggressive towards other pairs. Pacific Chorus Frogs continue to be heard calling, although we have heard them here in every month of the year. Reports from Portland indicate that the first wave of spring migrants have come in, with Say's Phoebe, Turkey Vultures and increasing numbers of swallows (Barn, Tree, and Violet-green) all reported recently. It won't be too much longer until a few of these reach southwestern BC.

One continuing trend is the burst of activity during the first hour of the day, starting half an hour before dawn. We managed to capture 21 of the 27 birds caught today within this first hour, and the remaining six birds were caught on two nets runs over the rest of the morning. Several birders and photographers in the area also noted the absence of bird activity mid-morning. Interesting birds that were caught included a returning Song Sparrow and Spotted Towhee that were banded last April and had not been caught again until now, a Golden-crowned Sparrow first banded in late November and a Pacific Wren first banded in mid-November. Looking at this winter's data so far, it appears that there may a population of around 40-50 of each Spotted Towhee, Song and Fox Sparrow, and probably 10-15 Black-capped Chickadees and Ruby-crowned Kinglets, and 5 Golden-crowned Kinglets.

Other observations included many waterfowl in the sewage lagoons, with the bulk consisting of Northern Pintail, Northern Shoveler, and Green-winged Teal. Six to eight Yellow-rumped Warblers (both subspecies) were seen hawking insects in the cottonwoods on the west side of the lagoons. These are likely the same birds that have been present all winter, but they can be tough to find at times.

Now that we are nearing the end of the winter period it will be interesting to see when our birds leave and when the first wave of migrants will show up. It can't be too far off...