A male red squirrel killed by a bird of prey in the Yukon. He was found far from his territory during the breeding season, likely looking for breeding opportunities (ie. checking out nearby female squirrels). Thanks to the snow you can see the hole where the bird caught him, then bird tracks leading to the spot where he was eaten. We occasionally find red squirrels killed by predators and try to use evidence at the kill site to tell who did it. It’s not common that the tracks are so nicely laid out like this – this story was pretty clear. Goshawks and great-horned owls are the main avian predators of red squirrels in this part of the Yukon, while lynx is the top mammalian predator.
Today (14 December 2015) Cameron Nordell will give a public seminar as part of his MSc thesis defense. Come hear about his research at 1pm in the University of Alberta Biological Sciences Building, room CW 313.
The expansion of the human footprint across the world is increasing the number of interactions between humans and wildlife. Many studies have quantified wildlife behavioural responses to humans and this is an active area of research with practical implications for species conservation. However, changes to individual animals behaviour may be influenced by the properties of the disturbance stimulus itself, the effect of the environment in which the interaction occurs, and the individual’s past experience, but these potentially important effects have rarely been evaluated. Additionally it is unclear how individuals behave in the hours following the departure of human disturbance. In southern Alberta and Saskatchewan, I quantified the flight initiations from the nest by Ferruginous Hawks (Buteo regalis) in response to approaching investigators and used digital video systems to quantify their behaviour following investigator departure.
In Chapter 2 I studied the flight initiation distance from the nest (FID) by adult Ferruginous Hawks. FID was related to the actions of the investigator, the anthropogenic landscape around the nest and the number of previous visits to Ferruginous Hawk nests by investigators. Approaches by humans on foot illicit longer FIDs than those in a vehicle. Approaches driving on private access roads that were infrequently used by vehicles were related to increased FID. My data show that shorter FIDs are related greater number of vehicles that pass near a nest, demonstrating a relationship between human disturbances around the nest and FID. Finally, Ferruginous Hawk FIDs increased as the number of previous investigator approaches to that nest increased. Chapter 2 highlights the dynamic and complex nature of the decision to initiate flight from the nest and provides new insight as to why FID varies between and within species.
Having explored factors influencing the Ferruginous Hawk’s decision to change behaviour in response to human disturbance in Chapter 2, Chapter 3 focuses on the behavioural consequence through time when disturbed by humans. Here, I used digital video footage of Ferruginous Hawk nests to document nesting behaviour of adult males and females up to 12 hrs following an investigator disturbance, and test non-exclusive hypotheses that may explain differences in behaviour relative to undisturbed control periods. On average, across the 12 hr sample period, female Ferruginous Hawk spent significantly less time on the nest following investigator disturbance relative to controls, but individual variation was high. Delivery of prey items to the nest not significant different between disturbance and control sample periods. Disturbed female time on nest, initially lower than control periods, returned to normal over the course of our 12 hr sample period. The duration of reduced time on nest by the female varied with age and number of nestlings, such that female time on nest returned to normal sooner following a disturbance for young nestlings, and with larger broods. Thus, I found support for both the harm-to-offspring and parental investment hypotheses. This is among the first studies to identify that disturbed animals demonstrate behavioural differences from normal for up to 12 hrs following disturbance.
The ability to adapt flight initiation behaviour to human approaches and the consistent delivery of prey when disturbed suggests that, Ferruginous Hawks nesting in the highly anthropogenic regions of southern Alberta and Saskatchewan demonstrate the behavioural plasticity necessary to coexist with some human disturbance to the nest site. However, I also found instances of Ferruginous Hawk flight initiation at large distances, and that some individuals reduced nest attendance for lengthy durations following a human disturbance. Understanding how these extreme behaviours affect reproductive success of Ferruginous Hawks is likely essential to understanding human impacts on the Ferruginous Hawk population in Canada. My research was intended to contribute to the ongoing conservation effort for this species, and I discuss potential implications for management in Chapter 4. My research provides novel insight into disturbed behaviour and can inform management policies in the future as human development in the grasslands ecoregions expands and increases the number of interactions between humans and Ferruginous Hawks.
On Tuesday, December 8, Justine Kummer will be presenting a public seminar for her MSc defence. Come hear about her research in the University of Alberta Biological Sciences Building room CW 313 at 1pm.
Every year a large number of birds die when they collide with windows. The actual number however is difficult to ascertain. Previous attempts to estimate bird-window collision rates in Canada relied heavily on a citizen science study that used memory-based surveys which may have potential biases. Building upon this study and their recommendations for future research the Birds and Windows citizen science project was designed to have homeowners actively search for collision evidence at their houses and apartments for an extended period. The first objective of the Birds and Windows project was to see how a more standardized approach to citizen science data collection influenced bird-window collision estimates and to see if the same patterns observed by memory-based surveys were observed using different data collection methods. Comparing the results from the Birds and Windows standardized searches and memory-based surveys revealed differences in absolute values of collisions but similar relative rankings between residence types. This suggests that memory-based surveys may be a useful tool for understanding the relative importance of different risk factors causing bird-window collisions.
The second objective from the Birds and Windows project was to gain a better understanding of the factors affecting collisions at residential houses. It currently remains poorly understood which types of buildings and windows are most problematic. Understanding whether neighbourhood type, yard conditions, house attributes, or window types have the largest effect on collision rates is crucial for identifying which mitigation options might be most effective. Factors at the yard level had the best model fit for predicting bird-window collisions at residential houses. Conservation efforts should target variables at this level and those factors that attract birds to an individual yard. As few homeowners are likely to take an approach that reduces the number of birds in their yards, focus should instead be given to bird-friendly urban design and developing the most effective window deterrents.
Finally, the effects of bird feeder presence and placement on bird-window collisions at residential homes was determined through a manipulative experiment. During the study there were 1.84 times more collisions when the bird feeder was present. However, there were no collisions at half of the study windows. High variance was observed in the number of collisions at different houses, indicating that effects of bird feeders are context dependent. Changing the occurrence, timing, and placement of feeders can alter collision rates but is only one of many factors that influence whether a residential house is likely to have a bird-window collision or not.
In conclusion, I provide recommendations for conducting future survey-based citizen science projects and outline the next steps for bird-window collision research in working towards stopping avian mortality from collisions with windows. I have thoroughly outlined a number of factors affecting bird-window collisions and the focus of future research should now shift towards reducing the problem. The Birds and Windows project saw a number of successes as a citizen science project and citizen science remains the best method for collecting large scale data in real-world scenarios and should continue to be used in similar experiments.
Mid-spring and late fall shots of the upper reaches of the Elk River, north of Elkford, British Columbia, looking east into Elk Lakes Provincial Park. This is a remote region of the Kootenays only accessible by a single, dirt road. The area supports abundant populations of grizzly bears, elk, moose, mountain goats, sheep, wolverines, and cougars. We are working hard to maintain the spatial integrity of this landscape so that these areas continue to support wild creatures and wilderness experiences for those who venture into them.
Post and photos by Clayton Lamb