Swinging soft hackles is a time-honored technique in trout fishing, proven to catch fish for centuries. While not as popular today, it remains a go-to method when other approaches fail. But the exact reason it works still feel mysterious. We’re instilled to dead-drift our nymphs, and for good reason… not many stream insects move in the way we swing flies. So anglers continue to speculate about why trout are attracted to swung soft hackles.
Surely, there is a logical reason why it works. And, if we understand WHY this strategy works, we can better understand WHEN to apply the technique for maximum effect. So let’s dig in.
The most obvious reason a trout would eat a soft hackle is because they think it’s food. But surely the down and across swung presentation isn’t natural or common in typical river insects… most trout food is taken as a naturally drifting item, and few insects are strong swimmers. But during certain life stages, insects may in fact match a swung approach. On my home river, splashy aggressive rises usually indicate that trout are taking caddis pupae in the upper water column. These rises really get your heart going, and demonstrate the burst of energy needed to capture a caddis pupa before they swim out of reach. Clearly, the trout know the speed of these caddis and respond appropriately. These splashy takes shows the split-second decision making needed to capture this prey. Many anglers know that when caddis are emerging soft hackles will work. But what about the other common stream insects, like stoneflies, mayflies, and midges?
Which hatches are best for swinging soft hackles?
First, stoneflies. Stoneflies undergo incomplete metamorphosis (nymph -> adult) and emerge by crawling ashore and emerging on streamside vegetation. Not a likely candidate for swinging soft hackles.
Next, mayflies. Mayflies are a diverse bunch and can be subdivided into different lifestyle groups: swimmers, clingers, crawlers, and burrowers. All undergo incomplete metamorphosis just like stoneflies. For anglers, these different types can be identified by their shape, and depending on the time of year, make much better candidates for swung soft hackle wet flies. Some suggest that mayfly duns (emerging mayflies) have hydrophobic qualities that allow emerging mayflies to avoid getting stuck in the surface film as they emerge. This quick rise through the water column could be an enticing natural phenomenon mimicked by swinging soft hackles.
Swimmers are hydrodynamically shaped and move throughout the water column more easily than other mayflies. This group, which includes BWOs, Callibaetis, and Isonychias, make likely candidates for mimicry with swung flies.
Clingers are usually flatly shaped as they hold on to the surface of rocks, where they graze for algae and periphyton collecting on river rocks. These types of mayflies, including Brown Drakes and March Browns, aren’t as readily available to fish outside of when they are actively hatching.
Crawlers are more agile and active feeders than clingers, navigating the calm water in the interstitial space between rocks on river bottoms. Since they move more actively than clingers, they are more available as drifting food to trout. Western Green Drakes, PMDs, and Red Quills are crawlers but migrate to the bank before emerging but could make good candidates for swung wet flies…if it’s the right time of year, and you’re on a river that supports these types of mayflies.
Burrowers are the least available as food, because (as their name suggests) they’re buried for most of their nymphal lives.
Now, more on caddisflies. Unlike mayflies and stoneflies, caddisflies undergo complete metamorphosis (larva -> pupa -> adult) in the water. Caddisfly larvae can either be free-living and predatory (active feeders), spin nets to collect drifting detritus (passive feeders), or case-building grazers (relatively inactive feeders). But when caddis pupate and initiate their adult life stage, they navigate swift currents to reach the water’s surface. They may be strong swimmers but the innate drive to break free from the water surface makes them vulnerable during this period and are often targeted by river-dwelling trout. Summer caddis hatches can extend for long stretches, making caddis pupa readily available.
Finally, midges. Midges also undergo complete metamorphosis, like caddisflies. Emerging midge pupa fill with gas to help them elevate to the water’s surface, which gives pupa a sparkling appearance. And though Midges may be small, they offer another opportunity for swinging (appropriately sized), slowly swung soft hackles.
What about swing speed?
A research team in Italy figured out that certain types of insects tend to drift at different heights of the water column. They found that most types of insects drifted closest to the bottom, but certain types preferred drifting higher in the column. Swimmers were much more likely to drift in the upper water column, while unsurprisingly, benthic (bottom-dwelling) and crawler invertebrates tended to hangout lower in the water column. So you can tailor your swing speed to match which insects are present and hatching during your outing at appropriate water depths. An active caddis or mayfly hatch might mean faster swings higher up in the water column, while midge hatches or non-swimming mayflies may require a slower drift speed for your swing presentation.
S. Fenoglio et al. 2004
If you’ve fished a down and across swung soft hackle, you know that the takes are very noticeable. Unlike a fish sipping dry flies, when a trout takes a soft hackle, you feel a stronger predatory response from the fish. It’s like the JV version of fishing streamers. Unlike nymphing, where fish can eat and spit out your flies rapidly, you rarely miss fish on soft hackles. By the time you feel the strike, that fish has already made up their mind and committed to your fly, leading to an electrifying jolt of excitement. But the fly still moves across currents, and looks drastically unnatural compared to the standard practice of dead-drifting flies. What entices the take?
Aside from the obvious visual cues, one theory suggests that vibrational sources in close proximity to a trout will elicit a strike. Therefore, the soft hackled feather on a fly might have properties picked up by a fish’s lateral line.
Yet, it’s more likely that fish pick up on visual cues to identify swung flies. Trout are widely accepted to be visual foragers. Trout have a large viewing window on either side of their body, they can pick up movement over a wide field of vision. I’ve read some general estimates that a trout’s viewing window is approximately 2.25 times the depth at which the fish is swimming. There is a trade off though. With eyes positioned on the sides of their head, motion detection is often only noticed by one of their two eyes, compromising their ability to gauge distances accurately. By the time your soft hackle is visible, and with the assumption that the fish recognizes the fly as escaping prey, a split-second decision is made. For anglers, this is more forgiving than the long period of determination prior to a dry fly or nymph taken in soft, calm water, especially when the fly can be closely inspected by their full field of vision. As monocular vision isn’t as strong as binocular vision for depth perception, the down and across swing of your soft hackle across currents may not be perceived as unnatural after all. In fact, it might be just what you need to throw a curve-ball at an otherwise picky trout.
What flies should you use?
Since swinging soft hackles is all about motion, don’t sweat the details of fly patterns. The key component is the soft hackled feather used to push water and provide movement at the head of the fly. Some like sparsely hackled flies, others like heavily hackled feathers; both work, but it probably depends on the depth of the fish and the type of insects you’re aiming to mimic. It’s easy enough to rectify depth changes with some split shot, or to speed up/slow down your swing with a mend.
Give it a try!
When’s the last time you swung a wet fly for trout? It might be time to try it again. It can be a very forgiving method to break up the standard paradigm of technical nymphing. Plus you could always take a break from swinging and dead drift soft hackled nymphs, they are equally effective this way. As summer sets in and runoff recedes, we might all want a break from flinging bobbers around, so take advantage. Plus it’s one of the easiest techniques in all of fly fishing. There will be plenty of time for nymphing during the winter.
Author Bio:
Andy Witt, scientist and angler obsessed with chasing and understanding all gamefish, writes on the intersection of science, conservation, and fly fishing for Due West Anglers, based out of Denver, CO.
Sources:
Mayflies 101. The Perfect Fly Shop. http://www.perfectflystore.com/laquatici2.html
K. Christopherson. Sorting Out Mayflies. https://www.coloradofishing.net/ft_mayfly.htm
A. Thomason. 2009. Bug Water. Stackpole Books
S. Fenoglio et al. 2004. Vertical Distribution in the Water Column of Drifting Stream Macroinvertebrates. Freshwater Ecology 19:3.
T. Sholseth. 2003. How Fish Work. Frank Amato Publications.
How Do Trout See? Vail Valley Anglers. https://blog.vailvalleyanglers.com/how-do-trout-see/amp/
What Can Trout See? Trout Pro. https://www.troutprostore.com/class/what_can_trout_see
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