{"id":414726,"date":"2026-01-17T06:04:09","date_gmt":"2026-01-17T06:04:09","guid":{"rendered":"https:\/\/www.newsbeep.com\/ca\/414726\/"},"modified":"2026-01-17T06:04:09","modified_gmt":"2026-01-17T06:04:09","slug":"these-fully-grown-sea-lions-wont-stop-nursing-and-scientists-dont-know-why","status":"publish","type":"post","link":"https:\/\/www.newsbeep.com\/ca\/414726\/","title":{"rendered":"These fully grown sea lions won’t stop nursing, and scientists don\u2019t know why"},"content":{"rendered":"

LISTEN | Full interview with researcher Alexandra Childs:<\/p>\n

As It Happens6:36These fully grown sea lions will not stop nursing, and scientists don\u2019t why <\/p>\n

Alexandra Childs never quite got used to the sight of fully grown Gal\u00e1pagos Islands sea lions happily suckling from their mothers\u2019 teats.<\/p>\n

\u201cYou did a double take every time you came across it,\u201d Childs, a PhD candidate in behavioural and marine biology at Germany’s University of Bielefeld, told As It Happens host Nil K\u00f6ksal.\u00a0<\/p>\n

\u201cYou went back to the computer, like, \u2018I’ve got to check the age again. Am I sure that this is what’s happening?\u2019 It blew our minds.\u201d<\/p>\n

Childs is the lead author of a new study documenting the prevalence of so-called \u201csupersuckler\u201d sea lions in the Gal\u00e1pagos, published last month in the journal the American Naturalist. <\/a><\/p>\n

The researchers found roughly 11 per cent of the population kept feeding on their mothers\u2019 milk well into adulthood.\u00a0\u00a0Childs said it would be like if humans kept breastfeeding into their teens and 20s. <\/p>\n

\u201cWhy? We have no idea,\u201d\u00a0 Childs said. \u201cWe can’t understand why mothers would continue to allow this, because it’s a lot of energy to give away to an offspring who is able to hunt for themselves.\u201d<\/p>\n

Suckling trains<\/p>\n

The study looks at 20 years of data from a population of Gal\u00e1pagos sea lions, whose scientific name is Zalophus wollebaeki.<\/p>\n

Sea lions can live to be about 23 years old, Childs said. Most of the Zalophus wollebaeki weaned from their mothers between the ages of 1.5 and 4.5 years, just before they reach sexual maturity, which is exactly what the researchers would have expected.<\/p>\n

Not so for the supersucklers.<\/p>\n

\u201cThese guys are carrying on way beyond that threshold,\u201d Childs said.<\/p>\n

\"TwoIt’s not clear why so many Gal\u00e1pagos sea lions engage in ‘supersuckling’ behaviour. In other species of sea lions, and some seals, it’s connected to food scarcity. (Alexandra Childs\/University of Bielefeld)<\/p>\n

The oldest individual they observed suckling, she said, was 16 years old \u2014 though that appears to be an aberration, not the norm.<\/p>\n

“So that’s [like] someone in their 60s still breastfeeding,\u201d Childs said.\u00a0<\/p>\n

Some of them, she said, made a group activity out of it, forming what the New York Times dubbed<\/a> \u201cmultigenerational suckling trains.\u201d<\/p>\n

\u201cWe saw the three of them in a row with mom nursing on the older female, and the baby nursing on the mum,\u201d Childs told CBC. \u201cSo we had grandmother, mom and baby.\u201d<\/p>\n

Other sea lions do it, too \u2014 but not this much<\/p>\n

Andrew Trites, director of the Marine Mammal Research Unit at the University of British Columbia, says this kind of behaviour has been observed in several other species of sea lions, and some seals, too, but not to this extent.<\/p>\n

\u201cIt’s way more extreme in the Galapagos,\u201d Trites, who was not involved in the research, told CBC. \u201cIt’s a really interesting study.\u201d<\/p>\n

Sea lions usually do this when there\u2019s not enough high-quality food to go around, Trites said, and the mother wants to ensure her offspring’s chances of surviving and reproducing.<\/p>\n

\u201cIt takes a lot of energy to grow, to become really big, and pups need a lot of energy,\u201d he said \u201cOne way that mums can ensure that pups are going to get big enough to become future breeders is to continue to provide them with milk.\u201d<\/p>\n

\"AThe study suggests the supersuckling could be a bonding behaviour, but more research is needed to find out. (Alexandra Childs\/University of Bielefeld)<\/p>\n

But the Galapagos study notes that supersuckling was more frequent during weather patterns that cause low sea surface temperatures, which is associated with higher food resources<\/a>. By contrast, it occurred less during weather patterns associated with high temperatures.<\/p>\n

\u201cWe actually found that it occurs more frequently during good conditions, so when there’s lots of food around,\u201d Childs said.<\/p>\n

While unexpected, Childs says this could be because it’s not too much strain on the mother to provide additional milk when she already has plenty to eat.<\/p>\n

Trites, however, isn\u2019t convinced. There are many factors that affect food supply, he said. <\/p>\n

To rule out nutrient scarcity as a cause, he says you\u2019d need to look not only at the quantity of food, but also the quality. For example, he says steller sea lions have experienced population declines when their diets consisted mainly of lower-fat fish. <\/p>\n

\u201cQuantity can be a little bit misleading,\u201d he said. \u201cIf you’re a lean mammal, it’s all about fat. You need lots of fat in your diet. And eating lean cuisine is not gonna do it for you.\u201d<\/p>\n

The study, itself, cautions it can’t draw conclusions from the weather patterns alone.<\/p>\n

Childs says there are a few other possible explanations for the Gal\u00e1pagos sea lions\u2019 propensity for supersuckling.\u00a0<\/p>\n

There could be an immunological benefit to supersuckling that scientists simply don\u2019t know about, she said.\u00a0<\/p>\n

Or, she said, it could be more of a social behaviour.\u00a0<\/p>\n

\u201cIt is possible that it’s a means of expressing a long-term relationship between the mother and the offspring,\u201d she said.<\/p>\n

More research will be needed to say for sure.<\/p>\n

\u201cMy time is done on the island, sadly,\u201d she said. \u201cBut we will hopefully have some new, fresh-faced, brave people to go out there and collect data for us.\u201d<\/p><\/p>\n","protected":false},"excerpt":{"rendered":"LISTEN | Full interview with researcher Alexandra Childs: As It Happens6:36These fully grown sea lions will not stop…\n","protected":false},"author":2,"featured_media":414727,"comment_status":"","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[26],"tags":[49,48,66,323],"class_list":["post-414726","post","type-post","status-publish","format-standard","has-post-thumbnail","category-wildlife","tag-ca","tag-canada","tag-science","tag-wildlife"],"_links":{"self":[{"href":"https:\/\/www.newsbeep.com\/ca\/wp-json\/wp\/v2\/posts\/414726","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.newsbeep.com\/ca\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.newsbeep.com\/ca\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/ca\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/ca\/wp-json\/wp\/v2\/comments?post=414726"}],"version-history":[{"count":0,"href":"https:\/\/www.newsbeep.com\/ca\/wp-json\/wp\/v2\/posts\/414726\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/ca\/wp-json\/wp\/v2\/media\/414727"}],"wp:attachment":[{"href":"https:\/\/www.newsbeep.com\/ca\/wp-json\/wp\/v2\/media?parent=414726"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.newsbeep.com\/ca\/wp-json\/wp\/v2\/categories?post=414726"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.newsbeep.com\/ca\/wp-json\/wp\/v2\/tags?post=414726"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}