anon6789

I was trying to clear out my backlog of owl research papers to discuss, but I followed a citation to this short paper. Some very interesting stuff on how noise we generate impacts animals in ways that are probably not obvious to us.

Since most owls rely on hearing very quiet sounds to find food, it does not take much to interfere with that process. This study examined various noise levels and its effects on hunting.

Some key takeaways:

impacts of traffic noise on owls’ ability to detect prey has the potential to reach >120 m from a road. In other words, owls’ ability to detect prey was impacted even at the lowest level of TN (40 dB[A]) and was approximately 17% lower than detections in ambient sound conditions.

40db is equated to a quiet library or the hum of a refrigerator. 120 meters is about 400 feet for us in America. This is over twice the distance a prior study had shown background noise affecting bats, though that was a lab study while this owl study was done outdoors.

Distraction, in which owls attend to traffic noise rather than rustling sounds, could also explain declines in prey detectability and could operate along side masking. However, it is also possible that distraction or compromised attention could decrease with habituation to traffic noise over time. Distinguishing among these potential mechanisms must be a next step.

Good details to consider. I'm always ready to read more owl studies!

High frequency components of TN attenuate faster with distance from roads than lower frequency components, suggesting overestimation of the masking effects of TN playbacks at amplitudes reflective of 55, 105, 155, 205 m from the road. However, because APRS playbacks were louder than natural prey rustling sounds and APRS might be easier for owls to detect than actual prey rustling sounds with broadband energy, effects of TN on owls’ prey detection may extend well-beyond our 120 m estimate.

To answer your first questions: TN is traffic noise, APRS is artificial prey rustling noise.

Besides the omnidirectional broadcasting of the APRS not replicating the correct sound vectors of real prey, it sounds like they tried to compensate the effects of constant traffic noise generated against the simulated prey sounds since their recorded traffic noise didn't ebb and flow like actual traffic.

Nevertheless, given our playback is representative of traffic noise propagating from other roadways, it is likely that impairment of foraging at similar distances is generalizable to other roadways. Moreover, a recently published captive study showed that experimental playback of compressor noise, which has similar power spectrum with traffic noise, negatively impacts hunting behavior of northern saw-whet owls (Aegolius acadius) at sound levels as low as 46 dB(A), which corresponds to approximately 800 m from compressor stations.

That seems crazy at first. 800 meters is about 2600 feet or 0.5 miles! But considering how quiet a rodent rustling through leaves would be (35 dB max, by this study) that makes a lot of sense that it needn't take much to mask that level of sound.

These potentially sizable footprints from energy-sector and traffic noise highlight the pervasive impacts of noise on acoustic predators because many sources of noise, including road densities, are high and increasing. For example, 83% of the continental US is within 1061 m of a road and globally, >25 million kilometers of new roads are anticipated by 2050.

This has a staggering potential impact to the owls! In a world where food is life, a 17% minimum impact over so much land mass sounds severely consequential! 😮

Moreover, it is critical to understand how common prey species respond to roadways and traffic and determine whether the cumulative effects are additive, synergistic or even antagonistic, as some nocturnal small mammals appear to increase in noise exposed areas and along roadways. Regardless of the shape of these interactions, it is likely that wild owls and other acoustically-oriented predators will continue to be impacted by noise.

This is why I decided to do this article first, despite it adding to my backlog. The original study I was going to share today was a study about how owls adapt to crossing roads, so I felt it made sense to cover the impact first.

Full article here if you want to read it all.

From Izzy Edwards

Beautiful Barnie in a 'bandoned building

From Ed Saternus

Bubo and Owlthena

My front yard owls... During the day, they chill in their perfectly sized burrowing owl bunker across the street... I was in my back lanai when I heard an eagle nearby. I looked up, and it was coming in low, heading for my front yard. I ran across the house, and out the front door, and the eagle had just passed right over the owls.

I'm already worried about this years owlets, and we don't even have eggs yet...

Cape Coral, Florida

From Back to the Wild Ohio

Last night we admitted this incredible Long-eared Owl after he flew into a window. He's currently stable and resting, but he's holding one wing a bit abnormally, so we are hoping to get him into our veterinarian for x-rays to rule out fractures or other injuries.

Long-eared Owls are one of the more secretive owl species in Ohio and are rarely seen, which makes this patient especially unique. Despite their tall "ears," those tufts aren't actually ears at all, they're feather structures used for camouflage and communication. Their real ears are hidden on the sides of their head and are asymmetrically placed, helping them pinpoint prey with incredible accuracy, even in total darkness.

These owls prefer dense conifer stands and roost quietly during the day, often blending in so well that you could walk right past one and never notice. Because they're so cryptic, injuries like window strikes can easily go unseen unless someone happens to witness it.

We're grateful to the kind people who made sure this owl got help quickly! Fast rescue can be the difference between life and death for wildlife.

Keep this guy in your thoughts!

From Lucy Rosen

I stood there watching this nest for hours. The faces.

The way she leaned in.

The way the baby tucked close.

The constant awareness.

The protection.

And suddenly I wasn't just watching wildlife

I was watching myself with my daughter.

That look that says,

I've got you.

That instinct to shield, to guide, to hover just close enough.

The exhaustion no one sees. The devotion no one questions.

People have traveled from far and wide to photograph this nest.

I just saw a mother.

From Lee Spalding

Our resident male Boobook in the middle with his two offspring each side of him (guessing male on his right and female on his left).

From Glenn Bartley

Another highly sought after species that I was lucky enough to see in Argentina was this exceedingly cute Buff-fronted Owl.

From Pavel Šmejsa

From Blackland Prairie Raptor Center

Even the small raptors, like this Eastern Screech owl gets x-rayed. A hood or towel is placed over the head to keep it calm. Wings and legs are spread out and taped down on our x-ray table. The x-ray is quickly taken and within a minute we can view the x-rays online.

From Dan Oh

While everyone was at the other place, I stayed in this place to enjoy and watch this pair...

The top one is EXTREMELY skittish and will go into the hole if you open the car door or move around even across the street.

The bottom is in deep sleep until 6:00pm.

Hope the love is the air.

Not a good place to share the location. If you know it... good for you, but it would be nice to keep it low.

From Stephen Rosenberg

Burrowing Owls in Florida are so easy to photograph it makes my two trips to South Dakota feel like a personality flaw. A few quick, low-effort grabs here. I'll return when the chicks are out, the light is better and the bar is even lower.

From Willie Go

Great Horned Owl family in Florida.