Wednesday, 23 July 2014

Still only two Killdeer chicks

Annette had another morning out on the water looking for the lost Killdeer chicks, but sadly there were still just two. However Darlene Luckins' comment on the previous post about the female chicks sticking with mum and males sticking with dad in different locations is interesting and may just give us some hope that this is what has happened here since there are two chicks and only one adult.

Killdeer family; there is an adult and two chicks in this picture. Can you see them?
Photo: Annette Cunniffe.

Killdeer chick. Photo: Annette Cunniffe.
Annette tells us it was a beautiful morning on the water at 06:30 hrs, a lovely time of day at this time of year before the heat gets too much. She had occasion to talk to the caretaker about the Killdeer family and he told her of the plethora of predators that live in the area; fox, coyote and hawks are all living nearby and of course there are the gulls to contend with. 

Mother and daughter? Father and son? Or just two Killdeers?
Photo: Annette Cunniffe.

These are a real danger to young birds and the chances of all of the chicks surviving in the best of circumstances is unlikely, and lets face it, the predators have to eat too... right? Apparently last year there was a duck nest and not one survived to hatch in the same area which does not bode well however they do seem to be having a better year this year!

Duck family, at least some hatched this year.

At least Annette was able to console herself a little with some other species being in the area for her to look at and photograph, like this rather tame Least Sandpiper...

Least Sandpiper Calidris minutilla. Photo: Annette Cunniffe.

this Spotted Sandpiper...

Spotted Sandpiper Actitis macularius. Photo: Annette Cunniffe.

and this handsome American Oystercatcher.

American Oystercatcher Haematopus palliatus; these birds appear each year but apparently never breed, at least successfully, the number of American Herring Larus smithsonianus and Great Black-backed Gulls Larus marinus on the small rock that they inhabit prevent this from ever happening it seems.
 Photo: Annette Cunniffe.

Tuesday, 22 July 2014

Benthos? What's that?

I am ashamed to say that I had to ask this question.

"It's what keeps your favourite group of birds alive and thriving for you to look at!" came the reply.

I was informed, for my education that benthos is the community of organisms that live under, on or over the bed of a body of water, be it freshwater or saltwater; scientifically called the benthic zone.

Long-billed Curlew Numenius americanus; feeding in the benthic zone. California, USA.
These creatures come in a variety of types and sizes and it is they that the waders are probing for in the mud at low tide which is the only part of this zone that is available to them.

Eurasian Whimbrel Numenius phaeopus; feeding on exposed mud at low tide. Western Division, The Gambia.

What the waders actually eat of course depends a lot on their bill size and shape, but in the end almost all wader prey items are part of this group of creatures called benthos. These little critters are labelled in various ways including where they dwell; there are endobenthos that live under the sediment,

Hudsonian Godwit Limosa haemastica; using its long bill to probe deeply for endobenthos, Rio de Janeiro, Brazil.

then there are those that live on the surface of the sediment, these are termed epibenthos

A Piping Plover Charadrius melodus; short beaks find epibenthos at the surface of the substrate. Florida, USA.
and lastly there are the hyperbenthos which live just above the sediment.

Andean Avocet Recurvirostra andina; sweeps for hyperbenthos under the water, Antofagasta, Chile.
If you are one of these creatures and you measure over 1mm in length, then you will be deemed to be one of the group of macrobenthos. Not much macro about being 1.1mm in length you might think, but when you consider at the other end of the scale the microbenthos are under 0.01mm in length, and that is small by any standard. If your stature falls between these two you will be classified as an example of meiobenthos.

Horseshoe crab Limulus polyphemus; if macro benthos are anything over 1mm long then this should be called megabenthos! Connecticut, USA.

So are they animal, vegetable or mineral? Well the former two actually, the two types of benthos are the animals that are called zoobenthos and the same for the plants which are called photobenthos.

New Zealand Dotterel Charadrius obscurus; anyone for zoobenthos? Waikato, New Zealand.

But what are these creatures? At the big end of the scale we are talking about seagrasses, worms, starfish, crabs, shellfish, sea cucumbers etc. which are all recognisable to us, but on the smaller scale they can be tiny shrimp-like creatures to worms and even macroalgae.

Bivalve molluscs, edible benthos. São Paulo, Brazil.
Photo: Elis Simpson.
The lower forms in the food chain eat algae and detritus, these will then be eaten by smaller predators and so on up to the top of the chain.

Freshwater macro/zoo/hyperbenthos, European Bullhead Cottus gobio; Hertfordshire, England.

So next time you go to the shellfish stall at the seaside, just ask for a few grammes of benthos and see what you get!

Grey Plover Pluvialis squatarola and Hudsonian Whimbrel Numenius hudsonicus; California, USA.
Benthic artisan at work; pattern left in the sand by an excavating crab, also known as wader food. Eastern Australia, Australia. Photo: Elis Simpson. 

Monday, 21 July 2014

Killdeer chicks down to two.

We decided to follow this family's fortunes vicariously through Annette Cunniffe to see how they got on. Waders generally have a hard time raising young, but usually they are out of sight in inaccessible places. These Killdeers are raising a family where they can be observed so we are able to see what happens to the young birds, or at least see how many of them survive even if we do not necessarily know why, if not.

Still looking very downy the birds are developing fast.
Photo: Annette Cunniffe.

Last Sunday, the 20th of July, at low tide which occurred in the early afternoon Annette said she could now only locate two chicks. That's 50% mortality so far. The two she saw were with an adult. Here are the photographs of the two young birds that remain.

This individual is looking a lot less sleek retaining much more of its downy chick feathers.
Photo: Annette Cunniffe.
While she was there Annette noticed a Spotted Sandpiper as she was leaving on the edge of the lawn and shrubs at a relative's place right by the vegetable garden and thought this odd. Can't say we get many waders visiting our vegetable patch, such as it is.