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I love southern California. I truly do. Although it is disconcerting to look outside — or even step outside — and never really know what the season is, the weather is always beautiful here. The beauty of the region pales for me a little this time of year though. Why? Because we get curious, muted springs. True, Orange-crowned Warblers, House Wrens, and Bell’s Vireos have exploded into song. But it is only slightly warmer now than it was a month ago — and barely greener. The spring that I read so much about in the paper each day must be going on elsewhere.

Indeed it is. With ice off of our study lakes in Wisconsin and Minnesota, loons have returned to their territories. Most are reacquainting themselves with their mates of the previous year after eight months apart, foraging to recoup energetic losses from migration, and checking out potential nest sites.

But rest and recovery are not the only orders of the day for territory holders. The few weeks after iceout are a time of great peril. Young loons without territories probe those in their neighborhood for vacancies and weakness. These young adults try especially hard to seize territories where they observed chicks the year before. (Chicks on a territory are like a badge signalling its quality.) Breeders intent on holding their territories must invest considerable effort convincing young pretenders that an attempt to evict them would be costly and futile. Providing ocean conditions on the wintering grounds a few months before allowed them to prepare well for the breeding season, most territory holders do ultimately hold off all competitors and turn their attention to breeding.

Loons are not the only ones scrambling. With classes still in session until May 16th, I am stuck in California for two more weeks. While my Wisconsin and Minnesota teams are prepping for fieldwork, I am completing an endless stream of forms, contracts, online trainings, and other paperwork to help bring that about. On weekends, my wife and I ride our bikes toward the ocean and take in the mild greening and hint of warm weather that mark springtime in this part of the world. Yet a big part of me hungers to be on northern lakes, where spring arrives with a vengeance and loons fight tooth and nail for the privilege of rearing young for another year.

Sheila Johnston’s cool photo from this spring shows her favorite loon, Lena. Lena was a victim of an early-season eviction last May and spent weeks recuperating. We are delighted to see her back this year and re-paired on her old territory. With some luck, she and her mate will raise chicks on Upper Gull in 2025, just like the old days.

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I was skeptical when I first got the news from Melonie and Gin on East Fox Lake in Minnesota. “Larry”, they said, “has been missing for weeks.” Melonie and Gin have a bird’s eye view of the bay where the East Fox-South pair nests.* They know the bands of both adults, whom they call Larry and Lola. Very little that occurs on the territory escapes their notice. “We watch our pair like others watch TV”, Gin told me recently.

I should not have doubted them. And yet I am a scientist and have studied loons for 32 years. I am used to hearing reports of loon behavior that range from strictly factual and incisive……to 50% truth and 50% dramatization to….well, pure fantasy. So I followed up. “Missing?” I said dubiously. “He has not been positively identified since June 5th,” Melonie replied, “and we have seen only Lola incubating the eggs since at least a week before that.” She added that stretches of many hours had passed in early June during which Lola was off the eggs. Larry, who should have been incubating at such times, was not present. My team’s visits too confirmed Larry’s sudden absence.

I was convinced. Larry had vanished sometime in late May or early June.

Members of breeding pairs occasionally disappear. That alone is not news. Lead poisoning from fishing tackle, boat strikes, disease, and territorial battles sometimes claim one pair member in the middle of a breeding attempt. Faced with the loss of a mate, most adult loons — male or female — make a gut-wrenching but rational decision. They suspend the breeding effort, wait to find a new mate, and attempt to breed again later in the season, if time permits.

But Lola did not give up. In fact, hers is the first case we have documented of a loon of either sex losing its mate during incubation and incubating the eggs alone.** When both eggs hatched successfully on June 7th, Lola became a single mom.

Parenthood is a stressful business among loons. Lola had already challenged herself by choosing to warm the eggs on her own. Her obligation to protect and feed the two helpless hatchlings that emerged from those eggs raised the bar considerably.

I am not knocking Lola herself or females generally by describing the pickle she is in. Lola is a seasoned breeder who has proved she knows how to raise young. But female loons are 20% smaller than males. Indeed, at 3580 grams, Lola is slightly smaller than the average female. The real handicap that single loon moms face is the lack of a crucial vocal tool. You see, male parents save their families considerable time and energy by yodelling to discourage intruders from landing near the chicks. Lacking this vocalization, Lola must respond to territorial intruders either by hunkering down and hoping to remain unseen or confronting the intruders while stashing the chicks near shore.

The two chicks at East Fox-South are now two weeks old. As Melonie’s photo shows, they look good and are being fed steadily by their devoted mom. They are also of similar size, which suggests that Lola has been able to satisfy the needs of both chicks and prevent the corrosive sibling rivalry that often occurs in two-chick broods. But the family still must survive countless territorial intrusions and eagle flyovers before the chicks reach independence. Keep a good thought for them!

* Thanks to Melonie Elvebak for this nice photo of Lola alertly watching out for her brood.

** Back in 2005, a male on Alva Lake in Wisconsin faced a similar choice to Lola’s. An eagle killed his mate on the nest. Like Lola, he incubated the eggs alone for several days. But ultimately he could not balance his breeding attempt with his need to keep himself alive and healthy. So he gave up.

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The saying “success breeds success” was not coined with loons in mind. But we humans know from experience that an initial success can increase the likelihood of a second one. Indeed, I relearn the value of accumulated experience each spring during the period when I train field observers. With no background in the technique, new observers are utterly astounded when we locate the first nest of the year. After five more nest discoveries, though, they begin to develop a “search image” for nests. It is a thrill to see them learn quickly over a period of a few days to the point where they begin to point out loon nests to me!

Loons are not complete strangers to the benefits of learning. Males often place nests in poor locations when they first attempt to nest on new territories. After a bit of blundering about and some poor decisions, males typically find a nesting spot that results in a successful hatch. Afterwards, they reuse that good spot again and again, enjoying much greater success than during their first attempts. Thus, nesting success following an initial period of failure leads to further nesting success.

The impact of a loon pair’s nesting success on territory defense is another matter. The loon territorial system differs in a crucial respect from those described in other species. In many birds, most notably colonial seabirds, young adults prospect for good breeding sites by looking to see where other adults have produced chicks. When these young seabirds settle to breed, their settlement has little or no negative impact on adults already breeding at the huge colony. Not so in loons. Young adult loons prospecting for territories use chicks they spot on a specific territory as a badge indicating quality of that territory alone. Young prospectors must battle the current residents for ownership of such high-quality territories. That is, chicks seen in one year induce prospectors to return the next seeking to evict the owner of their sex and claim the territory for themselves. So adults that produce chicks experience the joy of parenthood…..but have also placed their future territory ownership in jeopardy.

The mixed blessing brought about by successful chick-rearing is nowhere more obvious than on the Pelican Lake-Mousseau Bay territory in the Minnesota Study Area. Online observers watching via the live nest cam were treated to a lengthy battle between two adult loons a few days ago. While the battle was shocking in its brutality, it was not surprising. We have long known that the successful rearing of chicks leads to a surge in interest in the territory and, hence, the likelihood of territory loss by one or both breeders. After raising two strapping chicks last summer, the male and female of Mousseau Bay must have braced themselves for a litany of territorial intruders and challenges. Indeed, the banded 2022 male apparently lost his position this spring; last year’s marked female is now paired with an unmarked male.

And yet there is hope. Yesterday, the old female laid an egg. She and her new mate both seem anxious to sit on it. If they can weather the blitz of black flies currently dogging their incubation efforts, they stand a good chance of repeating last year’s success.