The Vancouver Avian Research Centre is undertaking a number of specific projects and studies at the Colony Farm Banding Station:
Migration monitoring during April – May and August – October allows us to determine the significance of the habitat at Colony Farm as a stopover site for migratory birds. Many of the birds we band have large fat loads either initially or on their stopovers here which typically last for a few days to as much as a week or more. The caloric density of large fat deposits is enough to sustain the energy demands of small migrant songbirds making non-stop migratory flights of some 700 kms or more and this is just one of several such flights they must make to take them from their Central American winter grounds to their Canadian nesting grounds. Banding data allows us to prove the significance of the habitats these birds are using as refueling sites on their stopovers here.
During the breeding season (June – July) all birds captured are examined for breeding characteristics to determine which species breed in the park and their preferred nesting habitat.
Breeding passerine birds develop breeding characteristics which help us to separate males from females in sexually monomorphic species which otherwise look exactly alike.
Many species are sexually dimorphic meaning we can sex the bird based on characteristics such as plumage coloration and/or size. But in sexually monomorphic species both males and females look identical and these species can only be sexed in the hand in spring and summer when they show these breeding characteristics i.e. a cloacal protuberance (CP) or a brood patch (BP).
In many monomorphic species, the male’s cloaca becomes enlarged and bulbous during the breeding season, the base narrow and tip swollen, the purpose being to store sperm and aid with copulation. This is called a cloacal protuberance. Female passerines on the other hand conduct most if not all of the incubation and develop brood patches (BP). At this time they will lose the feathers on the breast and belly to facilitate direct skin contact and maximum heat transfer to the eggs for incubation.
7 of the 8 species of North American swallow are found in the park – only Cave Swallow is missing as a banded bird! We are studying the influence of crop type (pasture, silage, cereal and monocultures) on the abundance of aerial insectivores and how it affects the density of foraging swallows, particularly Barn Swallows in the park.
In studies in the UK it has been determined that aerial insectivores over pasture fields was more than double that over silage, and more than three and a half times greater than that over cereal fields and monocultures. Pasture fields also hosted twice as many foraging Barn Swallows as both silage and cereal fields. The results from the UK suggest that past reductions in the availability of pasture has reduced the number of aerial insectivores which in turn has added to Barn Swallow population declines. Maintaining old field habitat will help to maintain breeding Barn Swallow populations and we will continue to monitor and study swallows in the park.
Radio Frequency Identification – Tree Swallows
Radio frequency identification (RFID) allows the unique identification of individuals and automated recording of the presence of tagged birds at fixed locations such as nest boxes.
RFID is a means of contact-free electromagnetic communication between a reader and a transponder. In this application, a passive integrated transponder (PIT) tag weighing less than 0.004% of the bird’s body mass is attached to the bird and transmits a unique identification number to a reading device with an RFID circuit board and antenna. Every time a bird with a PIT tag comes near the RFID reader, the bird’s identity is recorded along with the date and time of the visit. The resulting data can provide incredibly detailed information about the behaviours of the tagged birds.
Tree swallows are familiar birds in coastal British Columbia, but their abundance has declined in the last 40 years due to unknown causes. Since they readily accept nest boxes, Tree Swallows represent an ideal candidate species for the use of RFID technology. The main objective of this project is to develop RFID capability to study the nesting behaviour of tree swallows in the park. The technology is being used to better understand the connections between adult nesting behaviour, and weather, food availability and nestling growth and survival.
This research is using innovative technology to address important ecological and conservation questions, while fostering new external collaborations and providing students with a significant experiential learning opportunities.
Swainson’s Thrush regularly overlaps its molt with migration. Birds may continue to migrate while actively molting or they may initiate and/or complete their molt in an area south of their breeding grounds. Where arid conditions on the breeding grounds in late summer are not especially conducive to molting, adults of several species including Swainson’s Thrush routinely migrate substantial distances to special molting areas.
In general, their movement away from increasingly drought-stricken breeding habitats is timed for their arrival somewhere in the desert Southwest US or Mexico during the period of monsoon rains. The flush of insects associated with these rains constitutes a bumper-crop resource for the energy and protein-demanding molt process.
All Swainson’s Thrushes caught for banding at Colony Farm during the post breeding season (August / September) were in flight feather molt indicating that Colony Farm may well be such a special molting area. We will continue to study and document this phenomenon in coming years.
Post Breeding Monitoring of Juvenile Birds
During the post-breeding season (August – October) capture rates of hatch year (HY) birds increase dramatically. By monitoring the numbers of adults and juveniles caught for banding we can better understand population growth and dynamics.
The combination of diverse, structurally complex plant communities and the presence of resources – food, water and shelter with high aquatic insect productivity in spring and high insect/fruit production in fall – that are typically present in the Park, provide a high-quality environment for migrant birds.
Age structure for birds captured for banding shows that there are more sub-adults than adults (53.1%/46.9%) during spring migration and that sub-adults make up 90.4% of the total birds banded during fall migration. This is consistent with the age structure of captured birds during our years of monitoring, further supporting the importance of habitat at the Park for dispersing juveniles especially in the fall. Most birds (+/-90%) caught for banding during this period are hatch year (HY) birds born during the current calendar year.
Rare and ‘Specialty’ Bird Species
Colony Farm is located at the junction of the cities of Coquitlam and Port Coquitlam and is bisected by the Coquitlam River and bordered by the Fraser River. Enclosed on two sides by steep escarpments birds are funneled in to the park and many rare and ‘specialty’ species appear including:
- Brown Thrasher
- Western Kingbird
- Swamp Sparrow
- Ash-throated Flycatcher
- Northern Shrike
- White-throated Sparrow
- Dusky Flycatcher
- Lazuli Bunting *
- Northern Waterthrush
- Least Flycatcher
- Indigo Bunting
- Western Palm Warbler
- Gray Catbird
- Brewer’s Sparrow
- Northern Saw-whet Owl
- Eastern Kingbird
- Clay-colored Sparrow
- Long-eared Owl
We have a unique opportunity to study these birds in the hand and add to baseline data by collecting additional information relating to age, sex, molt and plumage criteria.
* VARC commenced a colour banding program for Lazuli Bunting in 2010 and enlists the help of local birders to report colour banded birds to help understand survival rates and the dispersal of these birds throughout the park. This program along with our species-specific studies all provide ongoing opportunities for avian research and conservation and we will continue to provide progress reports on these study programs as they continue to evolve.