To: <>, <>
Subject: eBird
From: "Steve Read" <>
Date: Tue, 6 Mar 2018 18:32:14 +1100
Hi all


Would not simpler metrics be the proportion of records (eBird lists) in a given 
area that contain one or more sea-eagle sightings, or the mean number of 
sea-eagles per eBird records for a given area?  These metrics would allow for 
variation in the number of observers, through allowing for variation in the 
number of eBird records. They do assume that birders are not attracted to an 
area because of the number of sea-eagles, though, but that could be a 
second-order problem.




(not a postdoctoral fellow in mathematics at the University of Melbourne... 
although 30 years ago I was a postdoctoral fellow in plant cell biology at that 
university! 😊)


-----Original Message-----
From: Birding-Aus <> On Behalf Of Jason Polak
Sent: Tuesday, 6 March 2018 4:46 PM
Subject: Re: [Birding-Aus] eBird


Possible, for sure. Here are some ideas that could be possible using the eBird 


1. You can use the total number of observers in a given area in a model for sea 
eagles. With this number you could estimate the mean number of sea eagles 
observed per individual, and see how this varies over time.


2. You could model each breeding year of the Sea-eagle more thoroughly by 
assuming that observations of Sea-eagles for individual birders follow a 
Poisson distribution for a specified area, and use a generalised linear model, 
incorporating a few different factors. Then, you could see how these models 
change over time.


Basically, if you get the data per individual report, you are treating each 
observation as a random sampling from some unknown distribution and use basic 
statistical methods to approximate the total population.


Some of it involves slightly advanced math, but it is accessible with a little 
study and if anyone needs pointers or help getting started with it, I'd be 
happy to provide some assistance---I am a postdoctoral fellow in mathematics at 
the University of Melbourne.





P.S. Saw my first White-bellied Sea-eagle in Jabiru!


On 2018-03-05 11:22 PM, Judith L-A wrote:

> So… supposing I want to see how numbers  of White-bellied Sea-Eagles might be 
> varying across years – Given uncontrolled numbers of observers reporting 
> variably to eBird, can it provide suitable long-term population info about 
> the species ?


> Judith

> SEQ 500m


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