Article by Sian E. Ford
As summer reaches its peak and the colorful migrants of Spring disperse, other less amiable birds can come into focus. I began bird watching and banding during my undergraduate studies in university and all I had ever heard of the northern goshawk was that they are rarely seen but are highly aggressive to the point of dispatching neighboring raptors viewed as a threat. The Latin name for this bird is Accipiter gentilis which is “gentle/noble hawk” which, while derived from their restricted use by the nobility for falconry in the Middle Ages, is an interesting choice given this infamous behavior.
My first encounter with northern goshawks came in Alberta during the summer of 2017 after my parents excitedly informed me that they had seen a pair in their yard collecting nesting materials. It was only a few weeks later when my parents came to realize their new raptor friends were also responsible for the decrease in visitors to their bird feeders. Late that summer I set out with my dad into the forest behind their countryside home in search of nest site. My dad had a rough idea of where it might be as he had tried to follow the parents previously but to no avail, so we set out in the early morning in muck boots, with our binoculars and high hopes. Once in the region where my dad had seen them before it took no more than two minutes before the birds appeared and we quickly learnt that their aggression had not been understated. In perfect silence, the much larger female dove at me in a warning pass barely a foot from the top of my head. The male soon followed and the two began calling in a frenzy, attempting to lure us in the opposite direction. I was astounded that both birds had remained completely undetected by me until they were directly overhead or had passed by me. Not wanting to further disturb their nest site or breeding we took the hint and hiked back out with both birds taking the occasional dive during our retreat.
Northern goshawks owe their maneuverability to their short, broad wings and long tail which allow them to hunt in their forest habitat. Their hunting strategy involves the silent stalking of prey preferring to strike undetected, but will pursue fleeing quarry at high speeds, recklessly diving through underbrush and even into water to catch a meal. A hunt may even conclude on foot! Northern goshawks have been observed chasing prey into denser brambles, running with a hurried, crow-like gait. Prey will include any mammal or bird it can catch and subdue sometimes more than twice the size of a northern goshawk, including other birds of prey such as osprey and great-horned owls.
Their circumpolar distribution gives them a total range of 30 000 00 km2 but their secretive nature makes it difficult to determine total numbers. Their elusive nature increased during incubation, where females will become quieter as they tend to a clutch of 2-4 eggs. Hatching occurs after approximately 30 days with fledging six to seven weeks after. During the sixth week, young northern goshawks become “branchers” as they leave the nest to sit in nearby branches. At this stage they begin practicing basic hunting skills by grasping and striking at branches and perches, often tearing away leaves and tossing them up and over their backs in a very comical gesture. By 3 months of age the young are fully independent of their parents.
Should a northern goshawk make it through their second year, the average lifespan in the wild is up to 11 years on average. However, deforestation of old-growth forests continues to threaten nesting habitat globally. Due to their preference for dense canopy cover, timber harvesting methods that reduce this cover are the most detrimental. In Europe and Asia northern goshawks seem more resilient to loss of dense canopy forest, but this adaptability is not universal and long-term regional declines are seen in Canada and the American southwest. Conservation and ecologically conscious harvesting of old growth forests is vital to the continuation of this incredible and powerful bird.
Dear members and friends,
It’s hard to believe the end of July is already upon us already. This summer, the site has been bustling with visitors, campers, wildlife, special tours, and much more!
We hope you enjoy reading the July 2017 Newsletter, which can be downloaded as a PDF by clicking the link in this post below. For those who will miss the Behind the Scenes Tour in July you will be pleased to read that there are some spots still available on the morning Behind the Scenes Tour on August 23rd at 10:00am.
Thank you for your support,
Ruthven Park staff
Article by Chris Harris, Environmental Physiology Technician at the University of Windsor
It is never difficult to tell when a rose-breasted grosbeak is being banded and processed in the banding lab. What begins as a mysteriously unremarkable bird bag immediately begins squeaking like a particularly angry dog toy when it is picked up. New banders learn that carelessly rummaging in that bag can result in an unexpected role-reversal when the grosbeak’s seed-eating bill grabs them first, suddenly leaving the bander as the one squeaking instead. With a bite that reminds me of my sister’s pinching phase during her preteen years, rose-breasted grosbeaks provide my favourite style of lesson in proper songbird handling techniques: painfully memorable, but ultimately harmless.
Aside from testing the toughness and commitment of new ornithologists, their abundance, tolerance of humans, and eye-catching appearance has made the rose-breasted grosbeak a frequent introductory species into the world of birds and birdwatching. The spring arrival at a backyard feeder of a black and white bird with a pinkish red throat and underwing has sent many rushing for a field guide to find out what this new bird could be that looks so striking and different from the familiar, year-round resident species they’ve watched all winter. Hopefully, once the new birdwatcher identifies that their feeder bird is a male rose-breasted grosbeak, they will continue reading about this species as it is the perfect ambassador for all birds.
First, when females arrive a few days later, the new birdwatcher will very quickly learn about sexual dimorphism given that females look completely different with their streaky brown and white plumage and yellow underwing. They may also notice a juvenile male and learn about molt and plumage maturation since juveniles retain their first flight feathers and juvenile males usually look mostly like a female but with a few male features such as pink in the throat and underwing. Rose-breasted grosbeaks are also long-distance migrants. A quick look at their range map will show that the first male arriving at the feeder was wintering in Central America or northern South America only a month prior. While breeding, both sexes sing, incubate, brood, and feed. It is rare for so many broad, core concepts of birds to be demonstrated so obviously in a single species.
A second reason the rose-breasted grosbeak is a perfect introduction to birds is that they exemplify the contradictions and complexity of relationships between humans and wildlife. They are considered by some to be beneficial for eating several agricultural pest insects and yet by others as a pest since they also eat buds, flowers, and fruit themselves. Their abundance and large breeding range in deciduous and mixed forests throughout eastern and central North America has led to them to be considered a forest edge species resistant to human impacts and disturbance and of little conservation concern. However, a recent series of studies suggest their breeding success may be sensitive to forest patch size and that many of the individuals that we see breeding in edges, backyards, and gardens face numerous threats and have too low a success rate to replace themselves. What appears as a common and widespread breeder comfortable in disturbed habitats may instead be a population that relies heavily on a few core, high-quality breeding areas. This demonstrates both a big limitation of using presence and abundance alone to measure population health and an all-too-frequent mechanism of sharp population decline in other species.
The last reason why they are a perfect example songbird is that, despite being a common and well-loved feeder bird, they are not well studied and there are a great many things we don’t know about the species. Very little is known about crucial details like survival rates, nesting success, time budgets, nestling diet, wintering, and migration. Much of what we do know is built upon anecdotal observations of a few individuals many years ago. For example, the knowledge that their diet is composed mainly of insects, seeds, and fruit, and even that they eat both crops and crop pests, comes mainly from a study of stomach contents from 1908 and a few supporting anecdotal observations in the intervening century. In the last 50 years, there are only a handful of studies on behavior, hybridization, and the impacts of forest management on breeding. Surprisingly, we often know even less about many other species of birds. So, whether you are just discovering birds or becoming reacquainted with an old favourite, take some time to look a little more closely at the rose-breasted grosbeak, they always have something to teach you.
Dear members and friends,
The busiest and warmest season of all has arrived at Ruthven Park! Our grounds are greener than ever with the rain and the mansion and grounds continues to be a draw for visitors from far and wide.
We hope you enjoy reading the End of June 2018 Newsletter, which can be downloaded by clicking the link in this post below.
We would like to wish you all a very Happy Canada Day! We are open Canada Day 9:30am-5pm.
Ruthven Park staff
Check our our news letter June 2018 Newsletter
The Gate House Office and Grounds: Monday to Friday, 9:00am to 5:00pm, Saturday and Sunday, 9:30am to 5:00pm
The Mansion: Traditional historic tours every hour on the hour 7 days a week starting at 11:00am with the last tour leaving at 4:00pm.
Phone: (905) 772-0560
Toll-free: (877) 705-7275
243 Haldimand Hwy. #54,
Cayuga, ON N0A 1E0