northern shoveler, Q&A (1 Viewer)

[tom baxter]

Today I was very confused with what I saw while birding in Cape May NJ. I viewed several ducks and am familiar with the birds that have been recently reported in the area. The two ducks that confused me were both clearly northern shovelers (Anas clypeata). They were feeding in a group mixed with normal shovelers but these two individuals were actively diving, something that I have never seen a shoveler do. Additionally, of the two one was male and the other female type, but both of them had a silvery wash that was very noticeable through my scope and not shown by any of the other shovelers in the area. The male had a green head and, as far as I can remember, normal plumage on the scapulars, but was mottled silver on the breast and the sides instead of white. The female was similarly marked with silver, but otherwise looked like a normal shoveler.

I thought these were possibly hybrid shovelers at first but nothing really makes sense because in order to hybridize with a diver it would have to cross genera. Also they looked too normally structured. I did think that they sat a bit low in the water but it was a stretch and its possible I fabricated that posture to fit my search for hybridization clues.

What as going on with these shovelers? Is this usual, because I have seen thousands and have never noticed anything like this before. Help please!

 

[wheatearlp]

Diving behaviour in (Northern) Shovelers has been noticed quite regularly at my local patch (Upton Warren) in Worcestershire. It seemed to be restricted to a small group of Shovelers present during the winters of 2011/12 & 2012/13, rather than all birds present - probably 6 or 7 of about 30-40 birds. It appeared to be a deliberate feeding strategy, perhaps to reach vegetation in shallow water that was just out of reach for normal upending. the 6 or 7 involved also fed in the more usual gyrating manner, so it wasn't a complete departure from the norm.

I haven't noted this behaviour this winter and no-one else has mentioned it (or at least not to me) so perhaps the individuals involved have not returned or the water levels (perhaps unsurprisingly given the amount of rain this winter) are too deep to make the diving behaviour worthwhile.

 

[Birdbrain22]

A few weeks back, I saw the saw thing in Cape May. For me it was the CMSP East Lighthouse Pond. In my case, there was a very large flock of dabblers of mixed species. However ALL the Shovelers and only the Shovelers were diving and not dabbling at all. I could only presume there was either vegetation or some tasty inverts at the bottom that they had a liking for and could not reach otherwise.

 

[fugl]

A fascinating thread. I see shovelers regularly at one of the local lakes and as an obvious birder am frequently stopped and asked about the "rotating cells" which are very noticeable in the winter months and attract a lot of attention from the public, but I've never seen a shoveler dive there (or at anywhere else for that matter). I guess for diving to occur, conditions have to be just right as Birdbrain suggests.

 

[Jeff Hopkins]

I've seen mallards dive at one of our local ponds, so a shoveler doing it would certainly not be out of the realm of possibility.

 

[tom baxter]

That's pretty interesting. This certainly confused me. I still am wondering then, was the silver chest a natural part of the northern shoveler molt cycle? An inbetween plumage that coincidentally happened to be coupled with this strange behavior and not show by any of the other nearby shovelers?

 

[Birdbrain22]

Not sure about the molt cyles of your particular birds, but all the Shovelers I saw that day(at that location) were diving. Both male and female of the Shovelers were diving and not a one from any of the other dabblers in the pond.

Many sites online say it is rare to see them dive... but obviously it can/does happen. Here is a youtube link showing it as well as another link that explains the why(I was able to read most of the study). It states that Northern Shoveler at one of the locations in the study changed feeding behaviors from surface or dabbling to deeper feeding(diving) due to the lower amounts of zooplankton available in colder weather. They concluded that in the change over to dive feeding because zooplankton is not abundant, the Shovelers are going after benthic(pond-bottom) inverts. I can only assume same was/is happening in Cape May.


http://www.youtube.com/watch?v=m_Qm5exaZt4

http://www.jstor.org/discover/10.23...9914907&uid=3739256&uid=60&sid=21103692379027