Fowl Play: When handling birds gets auk-ward

It’s owl in a day’s work When it comes to researching avian species, it is common practice among ornithologists to capture, handle, and band birds [4]. This is standard for monitoring populations, identifying individuals, and obtaining physiological and behavioral data. Nobody really questions this; it’s all an important part of getting the information necessary to understand the way that species behave and interact, and conserve populations effectively. But perhaps we should think about what the birds are thinking: how do they perceive being trapped, restrained, and often poked with needles? We present several hypotheses about how birds may perceive handling, how individual differences affect their response, and how this research dictates how you should react if you find an injured or baby bird.
A Western Screech-Owl being handled by a researcher. PC: Jessica Schlarbaum
Just a silly goose Perhaps birds understand that researchers are not trying to harm them and have their best interests in mind. Social media often portrays wild birds as enjoying being handled (look up owl cuddling videos), and even recognizing people as a savior; and why shouldn’t they? If they are not being harmed, they may understand the overarching intentions of their handler. The human equivalent would be a lifeguard rescuing a drowning victim. The victim would be willing to be grabbed and dragged to shore by the lifeguard, and would likely become calm once the lifeguard was present. If this is true, we would expect wild birds to stay willingly during handling and exhibit stable heart rates (HR) and levels of corticosterone (also known as CORT, a stress hormone) throughout the process. You can find lots of videos of pet birds online displaying calm behaviors such as preening, sleeping, rousing (when birds fluff up all their feathers: example here), and courting, which we might expect if a bird is relaxed.
A Barn Owl nestling in a rehabilitation center reacting to the handler by biting. PC: Nadya Dooley
Attempted murder What if birds don’t see being surveyed as cuddling? Imagine spending a relaxing day at the zoo when all of a sudden a tiger escapes from an exhibit. You see it slowly stalking you in the distance and it starts running at you. Most likely, your fight-or-flight response will kick into high gear- your heart rate rises, you begin to sweat, and absolute panic ensues. This is another way birds may perceive handling; something scary, synonymous to a predation event. If this is true, we would expect a flight response upon approach, as the bird would want to escape capture. During handling, we would expect to see escape behaviors such as struggling, biting, and taloning, in an attempt to escape; along with this would be a physiological fight-or-flight response, including an increased HR, CORT response, and body temperature [5-7]. After release, we would expect to see increased feeding to replenish energy from such a stressful event, decreased incubation, and potential nest abandonment; breeding and nesting birds are very sensitive to stress [8, 9]. Duck and weave! A third possibility is that the effects of being restrained, poked, and prodded, are not isolated to one alarming event. Could surveying have long-term effects, such that individuals are left with PTSD (post-traumatic stress disorder)? This disorder has been recorded in birds [10], and if this were the case, we would expect individuals to show symptoms such as increased aggression, decreased feeding, and long term avoidance behaviors, such as lower return rate to the area and trap avoidance. This is similar to the PTSD that humans experience after witnessing a traumatic event. The person avoids the site of the incident, becomes fearful when in similar situations, and often has lingering behavioral changes.
A nestling American Kestrel vocalizing after being removed from a box after being brought to a rehabilitation center. PC: Jessica Schlarbaum
Getting those feathers ruffled So how do avifauna respond to being handled, physiologically and behaviorally? Is it no-big-deal to them, pretty scary and life-threatening, or long-term mentally scarring? The reality of what we see during handling is a strong flight response upon approach, increased CORT, HR, and body temp during, and attack behavior/struggling [5, 11-16]. After the fact, we sometimes observe nest/patch abandonment and increased vigilance. However, birds do return to the site of handling annually in most cases [8]. The only time we see a long-term effect on behavior is when a bird is exposed to many handling events in a short period of time. We can safely conclude that birds definitely do not perceive handling as a “cuddling” event where we are perceived saviors. When experiencing a single handling event, the bird likely perceives this as a predation attempt and responds accordingly. In studies where multiple handling events are required for each bird, the bird is more likely to respond to this with chronic stress, perceiving the event as an incredibly impactful, negative event.
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A wood duck hatchling being handled by a researcher. PC: Nadya Dooley
Different Reactions to Handling Birds are incredibly intelligent and have individual personalities [1, 2, 17]. So just like people, every bird is different, and every bird will respond differently to handling – you could say that some birds are more “chicken” than others. Individuals who have bold personalities will tend to have less of a CORT response to handling compared to those that are more shy (personalities are often determined based on how individuals respond to novel objects, among other things) [1-3]. Other birds are also used to being in closer proximity to people (think pigeons and blackbirds) because they live in the city, and there’s evidence that this makes handling less stressful [18-20]. There are also other ways in which birds will respond to being handled differently. There is evidence that predator bird species, such as hawks and owls, may be less stressed out by being handled than prey species such as sparrows and sandpipers [15, 21]. We speculate that this may be because they do not have as many natural predators to escape from, so stress responses are less important for them than a prey species [15, 21-27] . Age makes a difference too, as very young individuals who have not fledged yet also have a muted stress response. This is probably because they haven’t yet left the nest to start foraging on their own, a process which is associated with CORT [12, 28]. It all depends on the day too; if a bird hasn’t eaten in awhile and has few fat reserves, handling will be more stressful. Even weather makes a difference; it’s stressful for birds when it’s raining or snowing [6]! And if you wake a bird up when it’s supposed to be sleeping, it doesn’t go over very well [29-31]. Perhaps the worst offense is handling birds who are breeding, as they are significantly more stressed and may abandon their nest to try to find a safer place [13, 31-33]. That being said, older individuals with more experience and less chances to have future broods are less likely to abandon their nests [9, 34, 35]. So the way a bird will feel about getting grabbed and restrained depends on who it is genetically as well as what it is doing and how it is feeling at the time.
A wood duck hatchling being handled by a researcher. PC: Nadya Dooley
Things that toucan do Try to avoid handling or disturbing wildlife at all costs, especially nesting birds- keeping birds is “illeagle”. Remember, birds cannot tell that you’re trying to help them; you don’t want them to be in a state of constant stress from trying to survive a perceived predator attack. So if you do find an injured or orphaned individual, put it in a dark box to remove visual stimuli, keep it in a cool place to prevent overheating. and take it to a wildlife center as soon as possible to minimize stress. A couple more things to keep in mind: juveniles that are just fledging often end up on the ground hopping around. They’re usually fine and have a parent around that can take care of them while they learn how to fly. Nestlings (not fully feathered) shouldn’t be on the ground – if you can see a nest, try to return the bird there. The parents will not reject their baby based on smell. Here’s a great resource with more information on identifying baby birds and what to do if you find one.
Jessica Schlarbaum is a 1st-year Avian Science Masters Student at UC Davis in Dr. Josh Hull’s lab. She studies the nesting ecology and foraging behavior of Central Valley American Kestrels. Nadya Dooley is a 2nd-year Avian Science Masters Student at UC Davis, currently working in Dr. John Eadie’s lab. She is studying Wood Duck sociality and nesting ecology, and has long-term research goals in avian conservation.
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