The hunting of the woodcock and its future.
ANOMALIES on the ESTIMATE of the HUNTING BOARD
of BECASSE des BOIS in FRANCE
2013/2014 SEASON
Knowledge of harvest is the pillar of the management of huntable species.
All researchers, scientists, specialists agree.
In France for the Woodcock, we know the estimates of Oncfs removals for three seasons in thirty years. They are the only ones. The ministerial decree of 2011 was supposed to make it possible to know them, thanks to the use of returned sample books. But for ten years we have been waiting. The federations of hunters remaining overwhelmingly unable to have a return of more than 80% !
It is however the minimum percentage necessary for a reliable estimate of the withdrawals.
Table of raw data (15) of sampling estimates.
The result calls out. 44% drop in thirty years. Yet we have not read or heard many comments on the subject from the hunting world.
For ten years (14), I have been working on all the indicators at our disposal.
It's clear. The reliable knowledge of the samples makes it possible to assess, practically on its own, the state of conservation of the European Woodcock herd. All the other indicators serve to support the result.
For the 2013/2014 season, I studied in detail all the publications on the estimation of withdrawals.
ONCFS . Estimate of the woodcock hunting table in France for the 2013/2014 season, published in Faune Sauvage n ° 315, 2nd quarter 2017 (7) (pages 9 to 13).
Yves Ferrand, Kévin Le Rest, François Gossmann (Oncfs, Research and Expertise Department, Migratory Birds Unit - Nantes).
Philippe Aubry, (Oncfs Research and Expertise Department, Methodological Support Unit - Auffargis).
The methodology used breaks with that used for the two previous published surveys (1983/1984 and 1998/1999). (13)
Indeed, to estimate the removals by hunting in wild game populations, one possible approach consists in carrying out a survey of a sample of hunters. This is the choice that has been made so far in France for national surveys on hunting tables. These have never experienced a high response rate.
This cause of non-response leads to the declared withdrawals,
are on average higher than those of the hunters surveyed who did not respond. Coupled with a low response rate, this results in an overestimation of the hunting tables which can reach 20%, or even more.
(Ph Aubry - M Guillemain (Oncfs) press release - March 28, 2019) (11).
Faced with the often modest response rate during this type of survey, the Oncfs chose for the 2013/2014 season to use a method in several phases, intended to reduce the bias due to the lack of response from the of some people surveyed. The method in question was published in an international scientific journal PLOS ONE * (12) .
Departmental federations of hunters.
Thanks to the use of returned sample books, when the percentage of returns reaches 80% or more.
Indeed, according to Y. Ferrand Bécasse Oncfs network (6).
" The experience acquired during the application of the ministerial decree of May 26, 2005 establishing a PMA Woodcock in Brittany, allows us to formulate the hypothesis that a return rate greater than or equal to 80%, can be considered empirically, as sufficient for an extrapolation of the results to the departmental scale ".
Ten departments meet these criteria, including Finistère (88%) and Morbihan (80%).
For departments whose return is insufficient. The Departmental Federation of Gironde (1) is one of the few to have sought to know since 2011 the level and evolution of its samples. Thanks to a methodology composed of a sampling strategy on returned notebooks which would be perfectly valid from a statistical point of view, with to mitigate the bias due to non-returns, telephone surveys carried out by the members of this federation, among non-returns.
For the Landes, by the Regional Federation of Aquitaine hunters (3), with a comparable methodology, to find out the estimate of the woodcock removals of their five departments (including the Landes) and those of the Aquitaine region for the 2013 season / 2014.
The four departments studied are essential for attendance and samples in France. They represent about 30% of the total.
Comparative table between ONCFS, FDC and FRCA estimates of Woodcock hunting tables (Four departments and France) 2013/2014 season
* Without taking into account what the Oncfs indicated in 2014 (6). " The nocturnal abundance index (IAN) established by the Bécasse Oncfs / Fnc / Fdc network and the hunting abundance index (ICA) calculated each year by the National Bécassiers Club (Cnb) both rank the 2013 season. / 2014 above the 2000s average ". 736,129 would therefore already be overestimated compared to the average withdrawal of the last decade !
Assuming, as has been said but not proven, that the withdrawals from some departments were less overestimated by the Oncfs estimate ; given the weight of the four studied, the woodcock samples for the 2013/2014 season are however overestimated by at least 20% by the Oncfs survey.
In this case they would no longer be 736,129 but 600,000 at most.
Department of Finistère (5) .
This department deserves our attention.
It is the first French department for attendance and samples.
It is exemplary for the return (88%) and the use of sample books.
His withdrawals, through the use of his returned books, are 40,483.
If we make a gross extrapolation of this result, considering that the 12% of non-returnees take as much as the returnees, we obtain 46,000.
In reality, surveys carried out in several departments (Drome, Cher, Doubs, Aquitaine) with non-returnees show that they take much less than returnees.
I looked at three options.
Option A : non-returnees take on average only a third of returnees.
Option B : - - - only half -
Option VS : - - - that two thirds -
I chose option B, which allows the Finistère levy to be estimated at 43,241. Very close to reality. Percentage of error 2%.
The other two options allow us to estimate the range (42.322- 44.161).
For Finistère, how and why the Oncfs estimate comes to 61.843, while that of the Federation is 43.241 ? 30.5% difference .
Other points are relevant in the table above.
For the four departments, although with different methodologies, we see that the differences are quite close ( 30 at 36%) , between the estimate of the Oncfs and those of the Federations.
The withdrawals estimated by the Federations are all at the bottom of the confidence interval of the ONCFS estimate.
Aquitaine region.
I analyzed the Oncfs (7) results published on page 11 table 1. Estimation of the region-by-region hunting table for Woodcock during the 2013/2014 season. Twelve regions for a total of 742,686 (558,667 - 926,707). I particularly studied the Aquitaine region.
Comparative table between the Oncfs estimates (7) and those of the Regional Federation of Aquitaine hunters (3), for the hunting tables of Woodcock in the Aquitaine region for the 2013/2014 season. Five departments :
Dordogne, Gironde, Landes, Lot et Garonne, Pyrénées Atlantiques.
For the Aquitaine region, there is a difference of (24%) between the Oncfs and Frca levy estimates. As for the departments, they are still at the bottom of the confidence interval of the Oncfs estimate. This similarity questions.
Knowing that the reliability of the methodology for using returned books, when they reach more than 80%, is difficult to dispute. Finistère, Morbihan (4) (10).
That it is not for us to doubt the reliability of the statistical methodology of the Oncfs (8) (9) (12) ; like those of the Federation of Hunters of the Gironde (1) and the Regional Federation of Hunters of Aquitaine (3).
It is therefore probable that the discrepancies observed in the samples come from the data collection carried out with the hunters.
The results do not plead for a good reliability of the Oncfs data collection ; the anomalies observed deserve some explanations.
I insist once again. For effective management of the species ; to ensure the continuity of his hunting with dogs ; the interest of the whole hunting world is to know the reliable estimate of the removals of the Woodcock each season. The return and use of the sample books distributed by the Federations, when they reach at least 80%, meet this expectation.
Today the national return is around 48%. It's not surprising.
Because the Federations which for ten years have given back a notebook to non-returning from the previous season : 1 ° Encourage offenders. 2 ° Do not respect the terms of the ministerial decree. 3 ° Give grain to grind to opponents of the hunt.
So when does it change ?
Philippe Vignac. Hunter Seeker Woodcock. JUNE 2020
Bibliography.
1 ° Departmental Federation of Hunters of the Gironde (2011). Woodcock sampling survey in Gironde 2010/2011 season. François Mimiague.
2 ° Regional Federation of Aquitaine hunters (November 2012). Estimation of woodcock removals. Method and results for the five departments of Aquitaine. 2011/2012 season. François Mimiague.
3 ° Regional Federation of Aquitaine hunters (November 2014). Samples of Woodcock in the Aquitaine region 2013/2014 season. Method and results. Ph Mourguiart, Valérie Cohou, Claire Dauga.
4 ° Departmental Federation of Hunters of Morbihan (I hunt in Morbihan n ° 42 March 2019). Evolution of woodcock removals in the Morbihan seasons 2009/2010 to 2017/2018.
5 ° Departmental Federation of Hunters of Finistère (Le Chasseur Finistèrien n ° 132 March 2019). Woodcock samples from the 2008/2009 to 2017/2018 seasons.
6 ° Faune Sauvage (2014) N ° 305 (4th quarter). The maximum authorized harvest of the Woodcock : Review of two years of application at the national level. Yves Ferrand. Oncfs. Cnera migratory avifauna Nantes.
7 ° Faune Sauvage (2017) N ° 315. Estimate of the woodcock hunting table in France for the 2013/2014 season. Y Ferrand, K Le Rest, F Gossmann, Ph Aubry.
8 ° Faune Sauvage (2019) n ° 322 January-March. The survey on shooting tables for the 2013/2014 season : Some elements of understanding concerning the implementation of the sampling device. Philippe Aubry, Methodological support unit, Oncfs research and expertise department.
9 ° Faune Sauvage (2019) N ° 323. What system for producing hunting table statistics for France? ? Comparison with the rest of Europe. Ph Aubry, M Guillemain.
10 ° Oncfs. (December 2015). Application of the ministerial decree of 05/31/2011 relating to the maximum authorized harvest of Woodcock and of the decree of April 23, 2010 relating to the maximum authorized harvest provided for by article L.425-14 of the environment code . Report for the 2013/2014 season.
Editor. National Office for Hunting and Wildlife. Directorate of Studies and Research. CNERA Migratory avifauna, in collaboration with the National Federation of Hunters.
11 ° Oncfs (2019). Press release March 28, 2019. Reliability of investigations into hunting samples. Philippe Aubry - Matthieu Guillemain. Oncfs Research and Expertise Department.
12 ° Plos One. Publication Oncfs (2019). Item : " Attenuating the noresponse bias in hunting bag surveys. The multiphase sampling stategy ".
13 ° Faune Sauvage (2016) n ° 310 supplement 1st quarter. Page 3. Philippe Aubry Oncfs, Research and Expertise Department.
14 ° Site : lachassedelabecassedesbois.com Woodcock. Evolution of France and Europe direct debits. Conservation status of European herds. Reality. Philippe Vignac September 2019.
15 ° Site : lachassedelabecassedesbois.com The corrected sample data gives the same result. 43% decrease in thirty years.
(1983/84 : 1.057.000 - 1998/99 : 935,000 - 2013/14 : 600,000).