StayiNatHome: how is nature reacting to our absence?

When the cat's away, the mice will play, as the old saying goes. The equivalent for today is: when the people are away, how does nature play?

New Zealand, and much of the world, is in an unprecedented state with most people isolating indoors or making limited local movements. Our roads and centre cities are largely empty, keeping us safe, while brave medical professionals work hard to stamp out the Covid19 virus (if that's you, THANKS!!).

While we're self-isolating, how is nature reacting to our absence?

The short answer is that we don't know. This is a first for everyone, including researchers and the wild species living around us. You can help find out by keeping a watch on the nature in your neighbourhood, and sharing with you find on iNaturalist NZ–Mātaki Taiao.

It's also well worth putting our thinking caps on now: what species are most likely to change as a result of our self-isolation? This thinking can inform what species we focus our efforts on observing now, as well as after the Covid19 crisis has past.

I'm going to list a few things I've thought of below, while chatting with colleagues and other iNat NZ users. There will be undoubtedly be things we've not considered yet so please add your thoughts in the comments below.

Roadkill

Let's start with the obvious one. Few cars mean fewer dead animals on our roads. Roughly a million birds get killed on NZ's roads each year (that's extrapolating out per km roadkill rates based on my 17 years of road kill observations in and around Christchurch, which are consistent with roadkill rates in similar countries overseas). New Zealand's traffic volumes have plummeted during lockdown, and initial indications are that roadkill has too.

That's a good thing if you're a species likely to get hit by cars. It's a bad thing if you're a harrier hawk or black-backed gull supplementing your food supply with roadkill. It will also be interesting to see if car-wary species gradually start to spend more time foraging along the road edge.

We've had only one roadkill observation from all of New Zealand so far during #StayiNatHome. It's this hedgehog observed by @christophercaine last weekend in Ashburton.

Cafe lovers

New Zealand's city centres are largely dominated by smart exotic birds that scavenge our scraps, like house sparrows, starlings, and sea gulls. With all of the cafes and fast food joints closed, and all the shoppers gone, there's going to be a lot less easy people food about for our city's savy scavengers.

How are they reacting? I'm not sure yet. It looks like there's been a drop in gulls in central Christchurch, and there are no longer big groups of house sparrows around the city's cafes. Where have they gone? Have many of the gulls left the city for the farmland and estuaries? Have the house sparrows spread out through the suburbs?

Have you noticed any increases, or decreases, in these birds in your neighbourhood? As I write this, we've only had 14 observations of house sparrows and 26 gull observations made during #StayiNatHome. Don't forget to keep an eye out for what's going on with the house sparrows and gulls in your neighbourhood.

@jovirens photographed some house sparrows this week shopping in a supermarket in Dunedin. The cafes and fish & chip shops may be closed but at least they've got the supermarkets.

Predator un-control

As far as I've been able to learn, the mammalian predator control done by council staff in city parks and reserves has not been considered essential and has largely stopped. This means that if you've got your own backyard traps, now is an important time to keep them active. It also means that the lockdown might benefit mammalian predators.

Are you seeing more wild mammals about? Thankfully, we're out of breeding season for these species, so their populations won't boom after a month of no trapping. Still, the longer lockdown continues, the more they'll benefit.

@malts was surprised to find this wild pig near their house in rural Solway, east of Auckland, last week. How long will it take for these animals to get bolder with reduced hunting?

Less mowing, more to see

With council lawn mowing and weed whacking reduced, it's going to be a good opportunity for weeds, and wild native plants, to increase. A month is not a long time for plant spread. Still, there may be more unmown and wild places in your neighbourhood where interesting plants can establish. Some of these might not have been documented in the wild in your neighbourhood (or in NZ) before. It is worth watching out for new wild things in previously mown places.

We're also coming into mushroom season and less lawn mowing will keep these mushrooms undamaged and obvious for longer across our cities. We've had 855 observations of 173 species of fungi so far during #StayiNatHome, which is phenomenal.

This could be an excellent time to document the mushrooms living in your neighbourhood. I'd wager that, with a little effort, you'll find fungi species that haven't been documented in your neighbourhood before. Maybe they'll be able to spread more spores this year too.

@reinderw found this brown-birch bolete under a birch tree in Christchurch on Friday. With less lawn mowing, big mushrooms like this are going to be easier to find, and they'll likely spread more spores.

Domino effects

The trickier things to predict are the consequences of the obvious changes. If sea gulls and house sparrows largely abandon our city centres, what will take their place?

Josie Galbraith, at the University of Auckland, did some neat garden bird research, showing that the gardens that fed bread to house sparrows had fewer native birds like grey warblers (riroiro). Apparently, riroiro prefer to stay away from rowdy groups of bossy house sparrows.

If house sparrows scatter, will natives like grey warblers move in? We don't know, but it sure would be interesting to know if that's happening.

@oscarkokako took this outstanding photograph of a riroriro in Dunedin this week. These grey warblers are tiny birds, smaller than a silvereye, but they make a distinctive and loud song (like this song recorded in Christchurch this week by @laura-nz).

Now's the time to make regular counts of birds in your neighbourhood, and keep it going to see how those counts change after the end of lockdown when New Zealand tries to get back to normal.

Expect the unexpected

We can make some informed predictions of what's likely to happen, and focus on those species. It's also worth casting our attention wider for surprises. Nature has a habit of surprising us.

If you notice something new happening in the nature of your neighbourhood, please post observations of it to iNaturalist NZ–Mātaki Taiao. That could be wild species you've not noticed before. It could be species that were common getting harder to find. It could be species interacting in ways you've not noticed before, or behaving in novel ways.

While we're #StayiNatHome, keep your focus squarely on supporting your whanau. In your spare moments, consider casting your eye about for the other species living in your neighbourhood, and think about how they're reacting to this strange time that we're all living through.

(And, seriously, I'd love to hear your ideas in the comments about other ways that NZ nature might be reacting to our country-wide self-isolation.)

Posted on April 5, 2020 09:57 AM by

jon_sullivan

Comments

Hi Jon, the thing I noticed most quickly was the clarity of the stream that runs through a park and reserve behind my house. Auckland streams are used for stormwater drainage and over 3 hectares of stormwater goes into this narrow stream. Obviously we haven't had a lot of rain, but with people not washing their cars as much, construction having stopped and less upstream pollution, the stream has become clear enough for the bed to be seen along its length within the park. It was enough that banded kokopu could be IDed in this part of the stream for the first time. https://inaturalist.nz/observations/40855230 I hope other freshwater systems outside of farming areas are doing better whilst we are all locked down. I wonder if the lack of sediment into the sea is noticeable too?

Posted by ryvesie about 4 years ago

Thanks @ryvesie. That's an excellent point! I'd not thought about that.

I've read that a similar thing has been noted in Venice where the lack of boat traffic has stopped all the sediment being kicked up in the water. The clear water is then bringing cormorants in because they can now see the fish they hunt. I'm not sure how much of this is anecdote, and how much is backed up by data, but it sounds plausible.

You're right—I can see something similar happening on a smaller scale in parts of NZ with vehicle-related and construction-related pollution run-off into NZ streams. We should be paying attention to changes in our cities' rivers and streams.

Posted by jon_sullivan about 4 years ago