[NatureNS] Nocturnal migration for the 3rd Week of October

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Thread-Topic: [NatureNS] Nocturnal migration for the 3rd Week of October
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n style=3D'font-size:12.0pt;fon
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Hi John,
I=92ve seen a couple of groups of ~20-30 Am Goldfinches passing through our=
 yard in Halifax recently, feeding high in the trees plus visiting feeders,=
 twittering away, then moving on after a half hour or less.  I had assumed =
that these were migrating groups en route, but this species never seems to =
figure in your flight call lists.
Does this mean that they really are in the business of migrating now but do=
 so silently so you miss recording them?  Alternatively does it mean that t=
hey are just wandering around locally for food in groups, but are not =91in=
tending=92 to migrate at all?

Generally, are there a lot of species that migrate silently that you would =
obviously miss recording?  Perhaps the ratio of flight calls to radar image=
s at the same site would be instructive, if possible to make these and if t=
hey can be quantified usefully (for instance, do the radar images cover mor=
e spatial volume than the acoustic recordings reach, and if so could you co=
mpensate for the difference)?

Presumably the flight calls are thought of as a coordination process to pro=
mote keeping that species group bunched together to collectively improve na=
vigation, or are there some other benefits?=97 calling while migrating must=
 have an additional otherwise unwanted metabolic cost.
Steve

On Oct 24, 2016, at 2:12 PM, John Kearney <john.kearney@ns.sympatico.ca<mai=
lto:john.kearney@ns.sympatico.ca>> wrote:

Hi All,
Nocturnal migration was down to 88 flight calls at Carleton, Yarmouth Count=
y, this week. The estimated minimum number of individual migrants was 78. T=
he most common species was White-throated Sparrow (23 calls) and Yellow-rum=
ped Warbler (11). Sparrows accounted for 63% of all calls, warblers for 25%=
, and Kinglets for 7%. Straggling warblers included a Black-throated Green =
Warbler and a Black-throated Blue Warbler.
The weather radar in Caribou, Maine, indicated a similar low volume of migr=
atory activity based on the density of echoes in clear-air mode.
A summary table is given below and tables and charts can be seen here<http:=
//www.johnfkearney.com/Carleton_YarmouthCounty_2016.html>.

Estimated


Call

Minimum

Species

Count

Individuals*

White-throated Sparrow

23

14

Unidentified Sparrow

11

11

Yellow-rumped Warbler

11

11

Savannah Sparrow

9

8

Song Sparrow

7

11

Golden-crowned Kinglet

6

3

Unidentified Songbird

5

5

Palm Warbler

5

5

Blackpoll Warbler

3

3

Lincoln's/Swamp Sparrow

3

3

Dark-eyed Junco

2

1

Black-throated Blue Warbler

1

1

Black-throated Green Warbler

1

1

Unidentified Warbler

1

1

Total

88

78

* Calls that are more than one minute apart plus calls that are less than o=
ne minute apart divided by three and rounded up to nearest whole number


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<html>
<head>
<meta http-equiv=3D"Content-Type" content=3D"text/html; charset=3DWindows-1=
252">
</head>
<body style=3D"word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-lin=
e-break: after-white-space;">
Hi John,
<div>I=92ve seen a couple of groups of ~20-30 Am Goldfinches passing throug=
h our yard in Halifax recently, feeding high in the trees plus visiting fee=
ders, twittering away, then moving on after a half hour or less. &nbsp;I ha=
d assumed that these were migrating groups
 en route, but this species never seems to figure in your flight call lists=
. &nbsp;</div>
<div>Does this mean that they really are in the business of migrating now b=
ut do so silently so you miss recording them? &nbsp;Alternatively does it m=
ean that they are just wandering around locally for food in groups, but are=
 not =91intending=92 to migrate at all?</div>
<div><br>
</div>
<div>Generally, are there a lot of species that migrate silently that you w=
ould obviously miss recording? &nbsp;Perhaps the ratio of flight calls to r=
adar images at the same site would be instructive, if possible to make thes=
e and if they can be quantified usefully
 (for instance, do the radar images cover more spatial volume than the acou=
stic recordings reach, and if so could you compensate for the difference)?&=
nbsp;</div>
<div><br>
</div>
<div>Presumably the flight calls are thought of as a coordination process t=
o promote keeping that species group bunched together to collectively impro=
ve navigation, or are there some other benefits?=97 calling while migrating=
 must have an additional otherwise
 unwanted metabolic cost. &nbsp;&nbsp;</div>
<div>Steve &nbsp;</div>
<div><br>
<div>
<div>On Oct 24, 2016, at 2:12 PM, John Kearney &lt;<a href=3D"mailto:john.k=
earney@ns.sympatico.ca">john.kearney@ns.sympatico.ca</a>&gt; wrote:</div>
<br class=3D"Apple-interchange-newline">
<blockquote type=3D"cite">
<div lang=3D"EN-CA" link=3D"blue" vlink=3D"purple" style=3D"font-family: He=
lvetica; font-size: 12px; font-style: normal; font-variant: normal; font-we=
ight: normal; letter-spacing: normal; line-height: normal; orphans: auto; t=
ext-align: start; text-indent: 0px; text-transform: none; white-space: norm=
al; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px;">
<div class=3D"WordSection1" style=3D"page: WordSection1;">
<p class=3D"MsoNormal" style=3D"margin: 0cm 0cm 8pt; line-height: 15px; fon=
t-size: 11pt; font-family: Calibri, sans-serif;">
<span style=3D"font-size: 12pt; line-height: 16px; font-family: 'Book Antiq=
ua', serif;">Hi All,<o:p></o:p></span></p>
<p class=3D"MsoNormal" style=3D"margin: 0cm 0cm 8pt; line-height: 15px; fon=
t-size: 11pt; font-family: Calibri, sans-serif;">
<span style=3D"font-size: 12pt; line-height: 16px; font-family: 'Book Antiq=
ua', serif;">Nocturnal migration was down to 88 flight calls at Carleton, Y=
armouth County, this week. The estimated minimum number of individual migra=
nts was 78. The most common species
 was White-throated Sparrow (23 calls) and Yellow-rumped Warbler (11). Spar=
rows accounted for 63% of all calls, warblers for 25%, and Kinglets for