Coyote Yipps

A Behavioral Reconstruction

I almost always post my own first-hand observations of coyotes, supported by photographs. This case is different. The coyote’s crossing to Alcatraz Island on January 11th came to me second-hand. What follows is therefore a combination of documented sightings, dates, tide information, and physical geography, with behavioral interpretation drawn from research and from nearly 20 years of observing coyotes. Where motivation or decision-making is discussed, it reflects informed behavioral inference rather than direct observation.

The Event

The coyote arrived on the island at 3:24 p.m. on January 11th. He was not seen again until January 24th, nearly two weeks later, and he has not been observed in the last two weeks — I did not see him when I was there this week.

This posting discusses the environmental conditions and behavioral context explaining both how the crossing could have occurred and why the coyote probably would have eventually ended up leaving.

It has been proposed that this coyote had been swept away while chasing prey near the shore, or attempting a shorter crossing, only to be carried toward the island by powerful ebbing or surging currents.

Indeed, ferry crews reported strong currents that day — 8 to 9 knots (about 10 mph). For context, even an Olympic swimmer would struggle against a 2-knot current. That day’s peak currents were amplified by heavy freshwater runoff from recent winter storms.

However, this swept away theory diminishes any intention on the part of the coyote and underestimates his intelligence and drive to survive.

San Francisco’s coyote population is essentially saturated, with at least 20 known families (see my map and research HERE). It is just as likely that this coyote chose Alcatraz — planning the swim to escape territorial pressure. Alcatraz was unclaimed territory with a dense food base, something he could have sensed.

Birds were everywhere: Cormorants, Sea Gulls, Geese. Apparently Snowy Egrets and Herons also nest there.

Currents, Not Tide Tables

San Francisco Bay has two high tides and two low tides daily, driven primarily by lunar pull. Tide tables show when water levels rise and fall, but they do not indicate how fast the water is moving. For any swimmer — human or animal — current speed and direction matter far more than water level.

When currents reverse direction — from in to out or out to in — there is a period known as slack water, when horizontal movement slows dramatically or stops. Slack water does not necessarily coincide with high or low tide, particularly in San Francisco Bay, where channel depth, shoreline shape, wind and fresh water runoff affect timing. Because of the massive volume of water passing through the narrow Golden Gate, slack water lags behind tide changes.

On January 11th, as measured by different stations, the relevant tides were as follows:

• Presidio Station (#9414290) recorded low tide at 12:41 p.m. and high tide at 7:25 p.m.
• Alcatraz Station (#9414792) recorded low tide at 1:18 p.m. and high tide at 8:05 p.m. (Alcatraz is further into the Bay, so later).

After low tide, current strength increased, then began reversing direction. By approximately 3:24 p.m., surface flow was shifting inward (flood phase), though strength varied by location.

Slack periods can last up to 30 minutes, especially near shorelines,  within eddies, and around islands. During slack water, the Bay may still appear visually low, with exposed rocks or mudflats, yet horizontal movement can be minimal. This distinction is critical: slack water — not tide tables — creates the viable window for crossing.

For the Crissy Field–Alcatraz route, the most relevant data comes from Golden Gate Bridge Station SFB1203: Slack time is 3:34 pm.  Human swimmers attempting the “Alcatraz Cross” typically aim for this time frame, which provides about 15–20 minutes of neutral water.

How long does “swim-able” water last? If you define “slack” as water moving less than .5 knots (which is calm enough for a human or coyote to swim straight), the window is not long: on a normal day it could last 30 to 45 minutes. During January, there were King Tides, higher tides, which is when the coyote swam, it would be shorter than that.

This is where the story gets really fascinating—and a little bit miraculous for the coyote. If his arrival was at 3:24 PM, the coyote actually timed its swim almost perfectly, albeit possibly by accident. San Francisco Bay is one of the most famously tricky bodies of water to navigate in the world.

TIMELINE: The Crossing on January 11

A standard ebb tide flows West, out toward the Pacific Ocean. If a coyote jumped into a strong ebb at Crissy Field, he’d likely end up under the Golden Gate Bridge or heading for the Farallon Islands, not Alcatraz.

However, the “Alcatraz swim” scenario relies on a specific local phenomenon called the Counter-Current (or eddy), combined with the timing of the transition. Here is how that “impossible” swim actually works:

1. The “Crissy Field Eddy”

While the main “river” of water in the middle of the Bay flows West during an ebb, the water right along the shoreline at Crissy Field doesn’t always follow the rules. Because the San Francisco waterfront is jagged, the outgoing water “trips” over the land, creating a massive circular eddy.

• While the center of the channel is rushing West, a smaller loop of water near the shore often flows East back toward the city.
• This would have given our coyote a “free ride” toward the East in the initial leg of his journey.

2. The Power of “Slack Before Flood”

He then arrived on Alcatraz ten minutes before slack. Slack is that brief, magical window where the water stops moving before it reverses direction.

• 2:20 PM: The ebb is weakening. A strong swimmer (or a determined coyote) can fight a weak current, but they mostly use the shoreline eddies to move East.
• 2:45 PM: As he moves toward mid-channel, the outbound (Westward) current is dying out. At this stage, the “push” West is no longer a 4-knot treadmill; it’s more like a lazy river.
• 3:24 PM: The coyote reaches Alcatraz just as the water goes still.

3. The “Alcatraz Cone”

Alcatraz sits like a giant rock in a stream. During an ebb, there is a “shadow” of calm water (and sometimes a reverse swirl) directly behind the island (the East/South-East side). If he timed his crossing to hit that “shadow” as the ebb faded, the water would actually pull him into the island rather than pushing him past it.

Summary of the “Coyote Physics”

Time	Location	Current Action	Coyote’s Strategy
2:20 PM	Crissy Field	Weak Ebb / Shoreline Eddy	Uses the Eastbound eddy to gain ground toward the city.
2:45 PM	Mid-Channel	Dying Ebb	Rows/swims across the weakening Westward flow.
3:24 PM	Alcatraz	Slack Water	Arrives when the “treadmill” has stopped completely.

In short: the tide wants to take him West, but by hugging the shore to use the eddies and timing the crossing for the “death” of the ebb, he turns a Westward tide into an Eastbound shortcut.

Although peak currents earlier in the day reached 8–9 knots, by 3:24 p.m. those forces had essentially zeroed out. He quite literally threaded the needle between two powerful movements of water.

Why the Marina–Crissy Field Route Was Most Likely

The strongest currents in San Francisco Bay occur beneath the Golden Gate Bridge and within deep shipping channels. Along the Marina and Crissy Field shoreline, however, water movement frequently breaks into eddies, counter-currents, and temporary low-energy zones of reduced flow, particularly during slack periods.

This shoreline offers gradual entry, minimal surf, and a clear visual line toward Alcatraz. It is a recognized low-energy/slow current crossing area used by open-water swimmers.

This coyote, by the way, is not from the North Beach family — all members of that family were accounted for after January 11th — so he originated elsewhere — and I’m speculating here that he might have come from the Presidio. I was hoping to get a photo of his face — I know a great many of the coyotes in San Francisco by their faces and might have been able to tell which family he was from.

Although ferry crews reported strong currents, peak flows are not continuous. The crossing almost certainly occurred during a brief lull when conditions aligned favorably.

Water could be seen in deep puddles, but also there were hoses for watering the gardens, and a ranger told me that cleaning vehicles regularly left plenty o water on the parade ground.

Landing on Alcatraz: Intentionality

The coyote emerged on the east–southeast side of Alcatraz, an area sheltered by a hydrodynamic shadow created by the island’s shape. The south and west faces experience stronger, more chaotic currents. The coyote’s landing was not likely a random landing: it was more likely consciously chosen.

There is significant evidence to support the theory that this was an intentional “mission”. So even, say, if he had been “swept” to the island unintentionally, I want to share this alternative scenario here.

From the San Francisco shoreline, Alcatraz is a fixed and highly visible target. For a dispersing coyote seeking unclaimed territory, it could appear as a “promised land.” January is a period of heightened territorial drive. While coyotes do not swim for recreation, they are intelligent and daring. This coyote probably saw the island as a potential territory and decided to “push the envelope”.

If he entered the water near Crissy Field or even the Embarcadero, he didn’t just “float” there; he had to maintain a specific heading to keep from being swept past the island. That requires active navigation. Coyotes use their front paws to paddle and their tails as a rudder. While he showed “steadfast determination,” the fact that he arrived shivering, depleted, and near-hypothermic suggests he did not fully anticipate the “harrowing experience” of the 1.25-mile crossing.

The chosen landing area is comparatively low-energy, climbable, and adjacent to calmer water. This apparently is consistent with how land mammals typically select exit points after water crossings. Animals do not enter water blindly — not coyotes, not wolves, not dogs. They test conditions repeatedly, feeling resistance with their paws, watching floating debris and foam, observing surface texture, and even smelling the water. Moving water smells different from still water. At slack water, surface movement loses directionality and resistance drops — these are changes animals readily detect.

Coyotes, wolves, and foxes are exceptional pattern learners. They patrol the same shorelines repeatedly, associating light, sound, wind, and bodily feedback with outcomes. Before attempting a long swim, this coyote more than likely had prior experiences entering the water, being pushed or rolled, and learning when not to try again!

There is strong comparative evidence — from seals, river-crossing wolves, Indigenous coastal peoples, and modern SF Bay swimmers — that crossings are timed around calmer water. Animals read the Bay directly, they don’t need charts!

Coyotes are “risk-aware.” He would not have been “stupid” enough to get swept away. If he went into the water, he likely knew he was capable of finishing the job. The “panting and shivering” seen in the video wasn’t a sign of failure; it was just the physical toll of a high-intensity workout in a cold “gym.”

He did not, and would not have chosen or gone to Angel Island which would have been a death trap for an outsider. Angel Island is much smaller (1.2 square miles) than a regular territory in San Francisco that runs 2.5 square miles. And Angel Island’s population of coyotes is 14-17, one family unit, on 1.2 square miles — that is crowded. Outsiders are not welcome and he would perish.

Coyotes are survivors first, explorers second.

The coyote’s footprint, a dead mouse, Sea Gulls drinking fresh water from a puddle. But did you know that many sea birds have a gland in the corner of their eyes that desalinates saltwater, so they can actually live on seawater!

The Swim

The crossing distance would have been approximately 1.2 to 1.4 miles, likely not in a perfectly straight line. A reasonable swimming speed for a coyote in calm water is 1.0 to 1.5 miles per hour, suggesting a swim lasting roughly 60 to 75 minutes at a steady, aerobic pace.

For land mammals, water is cold, disorienting, energetically costly, and limits defense. For this reason, animals choose exit points before entering water. Entry and exit are part of a single decision. A suitable exit would include solid footing, calmer water, climbability, and a solid shoreline scent. Calm water carries scent more effectively, while strong currents smear it.

Although luck might have been involved to some extent, this journey more likely involved competent environmental decision-making!

Why Alcatraz — and Why Leave

Islands offer short-term advantages: fewer predators, fewer competitors. Coyotes apparently evolved in fragmented, dynamic landscapes — floodplains, river islands, and edge habitats — and crossing water to reduce territorial chaos is a known survival strategy.

And with the existing “dense calorie” environment — a “high quality patch” — on Alcatraz, the small territory would serve him well when it comes to nourishment — whether he actually catches the birds or not — a ranger told me that his staff constantly picks up dead birds on the trail and toss them.

A reason keeping this coyote from leaving the island might be if he was become instinctively wary of entering the water  after his difficult swim. He looked worn out in the video, but, then again, any athlete, human or canine, would have been winded and cold after a mile long battle in frigid waters. If he was a healthy, dispersing young coyote, he likely had the muscle and drive to make the swim — a calculated risk rather than an accident. However, without the exact same “threading the needle” of tides he used to arrive, he could be swept out to sea. So why leave?

Being the intelligent animal coyotes are, he would get bored on Alcatraz: most of that is rock and concrete structures, with just a few tiny gardens and puddles of water which might soon dry up. So, while he may have won the “security lottery,” he has essentially moved into a very small, very boring luxury apartment with no plumbing. Coyotes are incredibly social and high-stimulus animals. A 2.5-square-mile territory in San Francisco offers a constantly changing landscape of smells, sounds, and potential mates. Alcatraz, by comparison, is a 22-acre rock that a coyote can patrol in less than 20 minutes.

Coyotes often explore new areas for days or even weeks, then abandon places that cannot sustain them — I would think that this is how the story would unfold if he is left alone.

Closing Thought

This is a capable swimmer, intelligently reading micro-conditions, waiting for a narrow window, committing fully, and later reassessing the suitability of the place he reached. This is coyote!

The remarkable part of this story is not that a coyote swam to Alcatraz —it’s that we noticed.

Hmmm, snacking where not permitted, a poison trap?? hopefully not currently used, the line showing where the sea water meets bay water (I think)!

Also see: https://coyoteyipps.com/2026/01/14/coyote-swims-to-alcatraz/ and https://coyoteyipps.com/2026/01/27/alcatraz-coyote-survived-its-swim-and-is-thriving/

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ADDENDUM from February 8th:

1) The dock on Alcatraz was shut down from February 7th through February 15th for repairs: there were no hoards of visitors on the island during this time. This is something the coyote would have noticed and seen from Crissy Field. It is something that may have spurred him to make the journey.

Biologists have stated there is no fresh water on Alcatraz. Biologists are not coyote experts. San Francisco itself has a desert climate and lacks natural water sources, aside from the 17 natural springs on the peninsula. Alcatraz does not have such springs. But BOTH places receive 2) lots of moisture and fog condensation. I was on Alcatraz on February 8th. Picnic tables were being scrapped/squeegied of the large amounts of water that had condensed on them overnight. This same moisture was on leaves and on metal surfaces on the island. I’ve seen coyotes here in San Francisco lap condensation off plants and off of guardrails, and when I’ve brushed my hand against the guardrails or the plants, my hands were soaked (as was my clothing if I sat on these). Condensation is a huge and important water source.

Top row: lots of water condensation on plants and smooth structures such as metals and picnic tables — this was 9 days after the last recorded rain on January 30th when 1.33″ fell on parts of the city; Bottom row: the one dwindling rain puddle on Alcatraz, puddle formed by the restrooms, an endangered cormorant — easy to catch for coyotes.

How do desert coyotes get their water? The mammals and birds, such as the birds and mice that live on the island, are made up of roughly 70% water, providing a significant portion of a coyote’s daily fluid requirements. Desert plants exist on the island: although prickly pear cactus pads aren’t in season right now — they usually ripen in late summer or autumn, agave is. While not as easy to eat as cactus pads, it stores a massive amount of moisture in their hearts and stalks** (see below).

I’ve also read that the kidneys of coyotes in the desert produce very concentrated urine to ensure as little water as possible is lost during excretion.

As of noon on Sunday, February 8th, there was still no news from the NPS that the Alcatraz coyote has been caught. The last real sighting was on January 24th. Although I was hearing that February 4th was the last sighting, that was the date the story went viral after NPS announced their relocation plan. As far as I know, no collateral evidence (scat, prints, carcasses) nor views of the coyote have taken place since January 24th, in spite of field cameras and traps put out. The traps only caught seagulls which I hope were not hurt by the traps.

Apparently leg-hold traps are the preferred trap used by the NPS — though they were banned and proclaimed illegal in 1998. In spite of calling these *soft collared traps* — and I studied this in detail in 2013 — any leg trap that is going to hold a coyote and not allow escape is not going to be gentle on the coyote. Coyote legs are often snapped and broken by these traps. They are considered cruel and inhumane which is why they were banned in 1998. Dogs have been caught in them and maimed. I was told by a ranger that leg-hold traps aren’t being used. My question is, then what IS being used?

If the NPS is being truthful with their reporting, for those rooting for the Alcatraz coyote, there is a high possibility that he already swam back. I was not able to get a photo of his face, so I won’t be able to verify unless I see him back in the Presidio, and in spite of what biologists say, they won’t be able to tell from where he’s from unless they gather recent scat from the 20 families in the city to compare it with. Let’s hope he swam back and is safe.

** About agave plants: how much water does an agave plant store?

An agave plant is basically a living water tank. For a large species like the Agave americana (the “Century Plant” found on Alcatraz), the amount of water stored is significant because the plant is roughly 88% to 90% water by weight. While the exact gallon count depends on the size of the specific plant, you can estimate it based on the plant’s weight. A full-grown Agave americana could be holding 50 to 100 gallons of liquid. A more common mid-sized plant (roughly 4 feet tall and wide) might contain 10 to 12 gallons of water. The agave doesn’t have a hollow “tank” of liquid. Instead, the water is distributed through three main areas:

• Most of the water is held in the thick, succulent leaves. This moisture is locked inside a dense, fibrous pulp to prevent evaporation.
• The “stem”/base of the plant (which looks like a giant pineapple) is a massive storage organ for water and carbohydrates.
• When an agave prepares to bloom, it sends up a massive stalk. If this stalk is cut, a sweet, watery sap called aguamiel (“honey water”) can pool in the hollowed-out heart. A single plant can produce half a gallon of this liquid per day for several months.

Because the water is locked in tough, fibrous leaves, it isn’t easy to get to. Bighorn Sheep use their tough mouths and hooves to shred the leaves to get to the moisture. Coyotes on the other hand chew on the softer edges of the leaves or eat the moisture-rich flowers and stalks.

On Alcatraz, the agave plants are massive and decades old. While they provide a huge “emergency reservoir” of water, the coyote on the island is likely finding it much easier to get its 10–12 ounces of daily water — yes, this is all a coyote needs to live — from the 70% water content found in the meat of the island’s mice and birds.