Andrew Abraham

With many thanks to: @celestemare.bsky.social, @ymalhi.bsky.social, @duvallecology.bsky.social, @jcsvenning.bsky.social, @fonsvanderplas.bsky.social, and many others not on bluesky

So, next time you sit down to dinner and immediately reach for the salt shaker, spare a thought for Africa’s salt-starved megaherbivores.

From crop raiding by elephants to moose collisions with cars due to road salting, wild animal movements, ecological impacts and conflict with humans are often driven by a desire to satisfy their salt cravings.

Where animals can't get enough salt in their diet, they may come into conflict with humans. Many protected areas are located in low-sodium environments; yet humans have artificially increased salt availability through activities like borehole water pumping and crop fertilisation.

While rhinos, kudu, springbok and zebra often gather at natural and artificial salt pans from the Kalahari Desert to the Maasai Mara.

Gorillas on the other hand are known to fight for the saltiest foods, in particular decaying wood stumps that accumulate high levels of sodium (photo credit: Jessica Rothman)

Salt limitation also explains several interesting behaviours exhibited by wild animals. In Kenya, elephants enter caves to consume the sodium-rich rocks, while in the Congo rainforest, they dig for salt in riverbeds

Together, these results provide a new explanation for the so-called 'missing megaherbivores' in West and Central Africa. There is enough productivity to sustain higher densities of elephants, rhinos and giraffes, but a curious absence of these largest-bodied herbivores.

Adding plant sodium availability improved statistical models predicting large herbivore density across Africa. We found that the largest species (megaherbivores) were the group most constrained in low-sodium environments, mirroring our previous work on the allometry of sodium requirements

Interestingly, we found that in any given place, grasses had approximately 1-2x more sodium than woody plants; a pattern that was reflected by grazers generally having higher dung sodium concentrations that browsers.

Over 1,300 dung measurements from across 20 different wild herbivore species confirmed our assumption that plant sodium availability is a major determinant of herbivore sodium intake.

We collected a large database of plant sodium concentrations from across Africa and generated high-resolution maps, which revealed multi-scale gradients
arising from sea-salt deposition, hydrology, soil chemistry and plant traits.

Humans live in a world abundant in salt. In fact, medical professionals warn most of us against the dangers of consuming too much. Yet, it is far from clear how wild herbivores get enough and if this may limit their abundance.

Earth's largest land animals are limited by salt.

Sodium availability constrains the density and distribution of elephants, giraffes and rhinos across Africa, and offers a new explanation for the so-called 'missing megaherbivores'.

www.nature.com/articles/s41...
Free access: rdcu.be/eTPY2

🦁Predators have a strong sex-bias when it comes to their favourite prey 🌏

In their new paper @andrewabraham.bsky.social quantify large carnivore sex-biases in Africa and examine how wildlife managers can replicate such effects when natural predators are missing 👇

buff.ly/Q8cB4Qq

Super important work by Tim Kuiper and co!

Great opportunity to lead discussions in biodiversity conservation for ECRs

Great project, with a great team!

Closing tomorrow! Last chance to apply for postdoc to explore the role of animals in savanna ecosystem productivity & nutrient cycling! Link to job: tinyurl.com/53dy4584 #savanna #termites #largemammals

Pretty simple instructions to follow

The "great whale conveyer belt" that transports nitrogen, carbon, and biomass from high latitude feeding grounds to concentrated low latitude breeding grounds in gray, humpback, and right whales.

Lovely figure by A. Boersma
doi.org/10.1038/s414...

Sure to be an interesting talk by @andrebellve.bsky.social.. also, be prepared for some excellent graphics! #scicomm

Beautiful sighting of a martial eagle eating a mongoose at iSimangaliso park today

Should we stop feeding birds, what happens if we do and does it spread disease? Half of British households put food out for birds but there is increasing concern it can spread disease

Half of British households feed birds.. but should we? Ft our recent study on potential issues of nutrient pollution.
www.theguardian.com/environment/...

Full paper: esajournals.onlinelibrary.wiley.com/doi/full/10....

The stunning power of whale pee A single whale can produce more than 250 gallons of urine in a day. It helps sustain life across the ocean.

Nice coverage by Nat Geo of our new paper quantifying the longest nutrient transport system in the world: whale pee

www.nationalgeographic.com/animals/arti...

For the full paper, see here: www.nature.com/articles/s41...

The Great Whale Conveyor Belt: Earth's Largest Mammals Keep Oceans Thriving Large whales operate what scientists have called “the Great Whale Conveyor Belt,” the largest long-distance nutrient transport on Earth.

We recap the whole study here: whalescientists.com/the-great-wh...

Our world is connected in many more ways than we think! Many thanks to a fabulous co-author team, led by Joe Roman @jjkiszka.bsky.social @luishuckstadt.bsky.social

But, industrial whaling has decimated whale populations, reducing this vital ecosystem process by about two-thirds. Today, conservation efforts have partially re-established the Great Whale Conveyor Belt, although climate change poses a new threat.

The whale-derived nutrients help support nutrient-poor tropical lagoon ecosystems, such as coral reefs. In Hawaii, we calculate that nutrient release by whales is ~1.5x more than abiotic processes, such as upwelling.

Each year, the whales undertake long migrations to give birth to their calves in warm tropical lagoons. In doing so, they transport vast quantities of nutrients such as nitrogen and release these in their urine, placenta and carcasses.