next message in archive
next message in thread
previous message in archive
Index of Subjects
--------=_MB4C06A131-C294-4E9C-9F3C-280A1937CD39
Content-Type: text/plain; format=flowed; charset=utf-8
Content-Transfer-Encoding: quoted-printable
Thanks Lance,
On the question of mechanisms I very much doubt that high acidity is=
=20
a factor. Perhaps chicken droppings are quite different from Cormorant=20
but, thinking back to chicken roosts indoors there was a strong odor of=20
ammonia; thus basic. And further, many temperate trees are tolerant of=20
highly acidic soils. If these droppings are indeed acidic then the=20
droppings in question should should have a "sauerstoff" taste; like=20
vinegar or sauerkraut.
If cormorants prefer rocky nesting sites then that in itself could=20
be a factor. If, for example, 90% of the potential rooting depth is rock=20
or coarse sand (>2mm), then only 10% of the volume is available to hold=20
water or nutrients so it would be vulnerable to dry weather and an=20
increase in NH4NO3 deposition which would be harmless on a decent soil=20
(90% <2mm) might lead to rank annual herbaceous growth (e.g. Atriplex)=20
and high rates of water usage until dry.
No doubt, as you say, the rate of deposition per unit area would be=20
a key factor. But I continue to wonder what happens in areas free of=20
winter kill potential.
YT, DW, Kentville
------ Original Message ------
From: "Laviolette, Lance" <lance.laviolette@lmco.com>
To: "naturens@chebucto.ns.ca" <naturens@chebucto.ns.ca>
Sent: 3/29/2018 6:47:23 PM
Subject: Re[3]: [NatureNS] Cormorants and Great Blues
>Hi David,
>
>
>
>Heron colonies may persist for a long time in the same location.=20
>Double-crested Cormorant colonies on the other hand quickly become=20
>treeless environments. The nest densities of double-crested cormorant=20
>colonies are much higher than that of great blue herons. It may be a=20
>question of the volume of guano produced in relation to the surface=20
>area the colony covers or perhaps double-crested cormorant guano is=20
>more acidic.
>
>
>
>Double-crested Cormorants prefer rocky nesting sites so it would seem=20
>there is an advantage for them to quickly change the vegetation=20
>structure to that of their preferred type. They=E2=80=99ll nest in trees u=
ntil=20
>the habitat is more to their liking and then it=E2=80=99s ground nesting a=
ll=20
>the way.
>
>
>
>Cheers,
>
>
>
>Lance
>
>
>
>From:naturens-owner@chebucto.ns.ca=20
>[mailto:naturens-owner@chebucto.ns.ca] On Behalf Of David
>Sent: March 29, 2018 3:39 PM
>To:naturens@chebucto.ns.ca
>Subject: EXTERNAL: Re[3]: [NatureNS] Cormorants and Great Blues
>
>
>
>Hi Again,
>
> My question was not about composition of guano but whether or not=20
>it kills woody perennials (especially trees) in areas where hardening=20
>off to avoid cold induced winter kill (largely dessication I think) is=20
>not a consideration; tropical to warm temperate. In extreme cases where=20
>the deposit rate is high and soil becomes buried I expect all plant=20
>life is killed.
>
> I visited a "Crane colony" in NS many years ago and there were no=20
>live and lots of dead hardwood trees but I don't recall any noticeable=20
>accumulation of bird droppings on the litter.
>
>
>
>Yt, DW, Kentville
>
>
>
>------ Original Message ------
>
>From: "Laviolette, Lance" <lance.laviolette@lmco.com>
>
>To: "naturens@chebucto.ns.ca" <naturens@chebucto.ns.ca>
>
>Sent: 3/29/2018 4:00:57 PM
>
>Subject: Re[2]: [NatureNS] Cormorants and Great Blues
>
>
>
>>Hi David,
>>
>>
>>
>>You are far more qualified than I am to understand the soil chemistry=20
>>involved. Guano is uric acid so I=E2=80=99ll hypothesis that the acidic=
=20
>>component damages the trees directly.
>>
>>
>>
>>Nick Hill might also be able to comment on the effect that gulls have=20
>>had on plant community succession on Brier Island. I=E2=80=99d be interes=
ted=20
>>to know if it is the soil chemistry of former colony locations=20
>>suppresses shrub and tree growth or if there is active destruction of=20
>>young growth by gulls.
>>
>>
>>
>>Cheers,
>>
>>
>>
>>Lance
>>
>>
>>
>>From:naturens-owner@chebucto.ns.ca=20
>>[mailto:naturens-owner@chebucto.ns.ca] On Behalf Of David
>>Sent: March 29, 2018 1:45 PM
>>To:naturens@chebucto.ns.ca
>>Subject: EXTERNAL: Re[2]: [NatureNS] Cormorants and Great Blues
>>
>>
>>
>>Hi Lance & All,
>>
>> I am guessing that tree death is due to winter kill of growth=20
>>which, due to excess N, failed to harden off. But, does guano also=20
>>kill woody perennials where winter kill is not possible (too warm) ?
>>
>>Yt, DW, Kentville
>>
>>
>>
>>------ Original Message ------
>>
>>From: "Laviolette, Lance" <lance.laviolette@lmco.com>
>>
>>To: "naturens@chebucto.ns.ca" <naturens@chebucto.ns.ca>
>>
>>Sent: 3/29/2018 12:26:34 PM
>>
>>Subject: RE: [NatureNS] Cormorants and Great Blues
>>
>>
>>
>>>Hi Everyone,
>>>
>>>
>>>
>>>That=E2=80=99s the usual cycle of Great Blue Heron and Double-creasted=
=20
>>>Cormorant nesting on Nova Scotia Islands.
>>>
>>>
>>>
>>>Grass > Brambles> Shrubs > Trees > double-crested cormorants/great=20
>>>blue herons > Trees > Shrubs/brambles > Grass
>>>
>>>
>>>
>>>Guano is a great fertilizer, rich in nitrogen, phosphate and=20
>>>potassium, but like any fertilizer, too much is not a good thing and=20
>>>as everyone who has visited a cormorant or great blue heron colony=20
>>>knows, they produce a lot of guano.
>>>
>>>
>>>
>>>The Great Blue Herons move to start the process on another treed=20
>>>island once the trees are all killed and can no longer support a nest=20
>>>structure (although I did come across Great Blue Herons nesting on an=20
>>>island in a lake in Yarmouth County once).
>>>
>>>
>>>
>>>The Grass stage is prolonged as long as gulls and/or the cormorants=20
>>>start nesting on the ground. Common Eiders can be in the mix at=20
>>>several stages.
>>>
>>>
>>>
>>&