Wild love:

Norfolk Wildlife Trust am­bas­sador Dr Ben Gar­rod on the star­tling truth about love in the an­i­mal king­dom

EDP Norfolk - - INSIDE -

Amorous an­tics in the an­i­mal king­dom

With spring just around the cor­ner changes in tem­per­a­ture, day length and even rain­fall all work to­gether to stim­u­late the small pi­tu­itary gland em­bed­ded deep in the brain which, in turn, in­forms the body to start pro­duc­ing eggs or sperm, or even some­times both. Yes, it’s Valen­tine’s Day and the whole world is in love.

But never ask a bi­ol­o­gist about the ‘fluffier’ side of the nat­u­ral world, be­cause we rel­ish the chance to tell you the truth be­hind what you see on those won­drous na­ture doc­u­men­taries. Nowhere is this more apt than in the case of love in na­ture.

If you are of a sen­ti­men­tal dis­po­si­tion and love the idea of love, then please, stop read­ing here. For the nat­u­ral world is a ver­i­ta­ble boil­ing pot of or­gies, cheat­ing and di­vorce.

Any­one who has ever been to a lo­cal park with a pond in the spring­time will have re­alised two things very quickly; that ducks are all per­verts and that monogamy might not be as preva­lent as we might think. The idea of hav­ing that ‘sig­nif­i­cant other’ is ap­peal­ing, sweet and heart-warm­ing, but alas is def­i­nitely not rooted in ev­i­dence.

In fact, true ex­am­ples of monogamy are very few and far be­tween in the nat­u­ral world. Even those ex­am­ples which we know for a fact mate for life might need a closer ex­am­i­na­tion.

Let’s get the mam­mals out of the way first. The vast ma­jor­ity are not in the habit of set­tling down with the love of their life.

Rats, mice, weasels and stoats for ex­am­ple are all polyg­a­mous, which ba­si­cally means that ei­ther or both par­ties in­volved have (to put it mildly) rov­ing eyes. Badgers are largely monog­a­mous, well, the males are at least, and although foxes are widely

known to be faith­ful to one an­other, one par­tic­u­lar study showed sur­pris­ingly high lev­els of polyg­yny (one male with mul­ti­ple fe­male part­ners), lit­ters with mixed pa­ter­nity and even in­cest.

In re­al­ity, of the roughly 5,000 or so species of mam­mals, only around 3% form life­long pair bonds. Of this lim­ited group who can claim the moral high ground are beavers, ot­ters, some bats and a few hoofed an­i­mals.

Maybe we should look to the birds to find ex­am­ples of true love. Star­ing out of the win­dow into the gar­den and let your eyes set­tle on the first bird you see.

Which species is it and is it monog­a­mous? Great tit? Nope, 30% are un­faith­ful. Blue tit? 40%. A house spar­row? At least one in five nests shows cheat­ing. In star­lings, it’s one in three and the seem­ingly shy and re­tir­ing coal tit shows a whop­ping in­ci­dence of 75% in terms of nests where ev­i­dence of an ‘ex­tra pair cou­pling’ is ev­i­dent.

Across the song birds, true (ge­netic) monogamy is only seen in about 15% of species. So, the gar­den isn’t the best place to look, maybe.

In the same way that the im­mor­tal line: ‘But we were on a break’ caused so many prob­lems, there is a prob­lem with se­man­tics in the area of monogamy across the an­i­mal king­dom. While 90% of all birds are so­cially monog­a­mous, they are not sex­u­ally or ge­net­i­cally monog­a­mous. It seems sneaky and it is.

In one es­pe­cially re­veal­ing ex­per­i­ment, male black­birds which were al­ready paired up with fe­males were ster­ilised. Bizarrely, those fe­males still man­aged to lay eggs that hatched. Awk­ward.

Surely swans, those bas­tions of love in the nat­u­ral world, can re­new our faith here? The good news is that swans re­ally do bond for life and are fiercely ded­i­cated to one an­other.

The com­mit­ted pair raises clutch af­ter clutch of cygnets through­out their life­times, learn­ing from fail­ures and suc­cesses. This op­por­tu­nity to learn may be one rea­son they stay loyal.

While mute swans are com­mit­ted, it is worth not­ing that Aus­tralian black swans (the black ones of­ten seen in parks) do rather let the side down and around one in seven nests shows signs of some­thing sus­pect, in a ge­netic sense. While they don’t (usu­ally) cheat, swans do some­times just give in and ac­tu­ally ‘di­vorce’ their part­ners, if they’re es­pe­cially use­less at rais­ing chicks.

Around 4% of swan cou­plings end this way, so that they might go on to find suc­cess.

With nei­ther birds nor mam­mals be­ing es­pe­cially good at restor­ing our faith in love, maybe we should look fur­ther afield. For many of us, one key spring time phe­nom­e­non is the sight of ponds full of frogspawn and the res­onat­ing sound of frog choirs take us back to our child­hoods.

We all recog­nise frog spawn and kind of know what’s go­ing on there but what ex­actly hap­pens when frogs get it on? Are they monog­a­mous? No, of course they’re not.

They’re worse than blue tits, even. Whereas it’s ac­cu­rate to de­scribe bird shenani­gans as ‘ex­tra pair cou­plings’, it might be more re­al­is­tic to de­scribe frog re­pro­duc­tion as an aquatic orgy.

It is those males who call loud­est and long­est that at­tract the ladies and on pa­per, it should end up with him clasp­ing onto the larger fe­male, wrap­ping his wrists around her, hold­ing on for dear life with spe­cialised ‘nup­tial pads’ as he fer­tilises the two thou­sand or so eggs she re­leases from her body. How­ever, there are of­ten a lot of other males who also have the same thought and in re­al­ity, what should be a ten­der amorous am­phibi­ous mo­ment turns into a slip­pery free-for-all where males get so ex­cited they all bun­dle on top of the un­for­tu­nate cou­ple in such a frenzy that some will grip and try to mate with rocks, pieces of wood, any­thing. Be­lieve me, be wary when stick­ing your hand into a spring­time pond.

Although find­ing that spe­cial some­one is close to our hearts as a species, it’s a very alien con­cept to our wilder nat­u­ral neigh­bours. Prac­tic­ing vary­ing it­er­a­tions of in­fi­delity does how­ever make some evo­lu­tion­ary sense.

It in­creases the ge­netic di­ver­sity of broods and lit­ters, which bet­ter pre­pares them against dis­eases and changes in the en­vi­ron­ment dur­ing their lives. It might also im­prove the chances of sur­vival of the young if the best pos­si­ble mate is cho­sen and it might even ben­e­fit the cheater in more di­rect ways, as there is some ev­i­dence that pro­mis­cu­ous fe­male birds might gain ac­cess to the ter­ri­to­ries of males with whom they dally.

So spare a thought this Valen­tine’s Day for your lo­cal wildlife. You might re­ceive a spe­cial card with a pair of lovedup an­i­mals on the cover. Just don’t read too much into it.

Dis­cover more of Norfolk’s wildlife this spring: nor­folk­wildlifetr­ust.org.uk

LEFT:Great crested grebe Podi­cepscrista­tus. A pair of adults per­form­ing the ‘weed dance,’ a spec­tac­u­lar part of their elab­o­rate courtship rit­ual Photo: An­drew Parkin­sonBE­LOW LEFT: Com­mon frogs Rana tem­po­rariaand spawn in a pond in West Run­ton Photo: David Ti­pling TOP RIGHT: Mute swans Photo: Dave Kil­bey

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