WhinCHAT II Holzinger et al - Availability of invertebrates as food for the Whinchat
Zur Verfügbarkeit von Invertebraten als Nahrungsgrundlage für das Braun kehlchen in der Bad Stebener Rodungsinsel (Oberfranken, Deutschland)
W H (Graz, Austria), M S (Grünwald, Germany), J F (Walberngrün, Germany), D F , L W G , S H L S (Graz, Austria)
H W, S M, F J, F D, G LW, H S, S L 2017: Zur Verfügbarkeit von Inver tebraten als Nahrungsgrundlage für das Braunkehlchen in der Bad Stebener Rodungsinsel (Oberfranken, Deutschland). WhinCHAT 2, 44 48. Availablility of invertebrates as food for the Whinchat in the vicinity of Bad Steben (Upper Franconia, Germany) The Whinchat ( Saxicola rubetra) is “cri cally endangered” in Bavaria (R et al 2016). While the ADEBAR survey of 2005 2009 resulted in 1200 – 1900 breeding pairs (R et al. 2012), the last survey (2014 2015) found only 455 BP in Bavaria. An important (former) popula on hotspot in Bavaria and Franconia is the farmland area around Bad Steben, Oberfran ken. The local popula on was about 50 – 60 pairs in the 1990ies, but declined to less than 10 pairs in this decade. The main causes are changes in agricultural land use and management: grassland usage was intensifi ed (earlier and more frequent mowing, pes cides, fer lizer), or grassland was ploughed, lesser parts got lost by usage as building land and by reforesta on. This project focuses on the ques on, if reduced availability of food might be a reason for the popula on decline. We studied the invertebrates densi es of three wet grassland habitats within whinchat territories (sites No 1, 2, 3) and three sites u lised by whinchats in the past but without breeding birds at the moment (sites No 4, 5, 6; see Tab. 1). We collected invertebrates during nine periods (= FP), each las ng 14 days, in 2016 and 2017 (see Tab. 2). Invertebrates were sampled by a malaise trap and a biocoenometer on each site. The malaise trap (Fig. 1) collects fl ying insects main ly, whereas the biocoenometer (Fig. 2), equipped with a pi all trap on ground and a trap on top of the tent, collects all species living resp. emerging within an area of 1 x 1m². For data analysis, we dis nguished between 17 invertebrate groups and counted the numbers of individuals (with body length between 1 and 11 mm) collected by the traps. In total, we gained more than 147.000 animals. 94.3% were coll ected by Malaise traps, 3.4% by pi all traps and 2.3% fell into the biocoenometer top traps. 56.4% were Brachycera fl ies, 23.8% Nematocera fl ies, 4.3% Aculeata, 3.0% beetles, 2.8% moths and bu erfl ies, 2.4% plant lice and 2.0% leaf and planthoppers. All other groups represented less than 2% of the total yield (see Tab. 3). Insect densi es diff er stronger between collec ng periods than between sites. The highest abundances were recorded in the second half of May. The number is reduced by 38.5% in June. This is most likely caused by mowing of the environs. Insect densi es increase slightly in July; the lowest numbers were recorded end of August. Biocoenometer data also show dis nct fl uctua ons between sites and collec ng periods, but we could not found any correla ons to the presence/absence of the whinchat. Due to the considerable general decline of insect biomass in the last decades (e.g. H et al 2017), we assume, that reduced availablility of food is a crucial factor infl uencing whinchat popula on decline on a landscape level. The improvement of known territories might be a suitable mi ga on measure for a short term stop of further popu la on loss, but in the long run we recommend the diversifi ca on of land use types in agriculture. Besides grasslands with tradi onal mowing regime (once or twice a year) we propose to establish unu lised riverine stripes along all water bodies and the establishement of large areas with very extensive all season ca le grazing (N et al 2016).
In Bayern gilt das Braunkehlchen als „vom Aus Rodungsinsel im Landkreis Hof (Oberfranken). sterben bedroht“ (R et al 2016). Die Der Bestand des Braunkehlchens ist dort von landesweite Erfassung 2005 2009 im Rahmen 50 – 60 Brutpaaren Anfang der 1990er Jahre auf der ADEBAR Kar erung (R et al 2012) ergab unter 10 Brutpaare in den letzten Jahren einge noch einen Bestand von 1200 – 1900 Brutpaaren, brochen. während bei der landesweiten Wiesenbrüterkar Um die Ursachen für den Bestandsrückgang erung 2014/2015 (L 2015) nur noch 455 BP quan fi zieren zu können, wurde ein gemein festgestellt werden konnten. sames Projekt vom Bayerischen Landesamt für Eines der (ehemaligen) Kernvorkommen des Umwelt, der Höheren Naturschutzbehörde der Braunkehlchens in Bayern ist die Bad Stebener Regierung von Oberfranken, der Unteren Natur
44 WhinCHAT II Holzinger et al - Availability of invertebrates as food for the Whinchat
Tab. 1: Lage der sechs Untersuchungsfl ächen im Landkreis Hof. Tab. 1: Loca on of the six study sites in the vicinity of Hof, northern Bavaria.
N . L K H S 1989 B 1 S B S , 50,341907°N 540 J 1989 J W B 11,644459°E 2 S B S , 50,353257°N 610 J 1989 J E L 11,633929°E 3 SW B S , 50,346031°N 610 J 1989 J NE F 11,626111°E 4 N B S , 50,380065°N 595 N E ( 1989 W L 11,654365°E 2008 ) 5 W B S , 50,377253°N 650 660 N E ( 1989 W L 11,585192°E 2008 ) 6 SW B S 50,336193°N 640 NEIN – 1989 A 2000 E G 11.612739°E J . N J R , . S 2013 R schutzbehörde des Landratsamts Hof und lokalen (Abb. 2) eine Fläche von 1 x 1m² bedeckt und hier Ornithologen ini iert. Ziel dieses Projekts ist es mit einer Bodenfalle und einer Kopfdose die auf festzustellen, ob die (mangelnde) Verfügbarkeit dieser Fläche lebenden bzw. sich entwickelnden von Insekten, Spinnen und Mollusken, als Nah Arthropoden quan ta v erfasst werden. rungsgrundlage für das Braunkehlchen, ein (Mit ) Zur Auswertung wurden die Inhalte der Fänge al Grund für die Bestandsrückgänge sein kann. Zu ler Fallen für insgesamt 17 Tiergruppen einzeln diesem Zweck wurde in der Umgebung von Bad ausgezählt, wobei nur Individuen mit einer Kör Steben die Häufi gkeit von Invertebraten in drei perlänge zwischen 1mm und 11mm dokumen gegenwär g vom Braunkehlchen noch besetzten ert wurden. Revieren (Flächen Nr. 1 bis 3) und in drei seit ei nigen Jahren verwaisten, ehemaligen Braunkehl In Summe wurden auf den sechs Flächen in den chenrevieren (Flächen Nr. 4 bis 6) vergleichend neun Fangperioden mehr als 147.000 wirbello untersucht (siehe Tabelle 1). se Tiere nachgewiesen. 94,3% der Tiere wurden mi els Malaisefallen gefangen, 3,4% stammen Die Erfassung der Tiere erfolgte über neun je aus den Bodenfallen der Biozönometer und 2,3% weils vierzehntägige Fangperioden (FP) in den aus den Biozönometer Kopfdosen. Jahren 2016 und 2017 (3 FP im Frühsommer 2016, 1 FP im August 2016, 4 FP im Frühsommer 56,4% der insgesamt gefangenen Tiere zählten zu 2017, 1 FP Ende August 2017, siehe Tabelle 2). den brachyceren Fliegen, 23,8% waren Mücken, Zum Einsatz kamen pro Fläche eine Malaisefalle 4,3% Taillenwespen (Bienen, Wespen), 3,0% Kä und ein Biozönometer. Die Malaisefalle (Abb. 1) fer, 2,8% Schme erlinge, 2,4% Pfl anzenläuse dient zum semiquan ta ven Fang vorwiegend und 2,0% Zikaden. Alle übrigen Gruppen stellten fl ugak ver Insekten, während das Biozönometer jeweils weniger als 2% der Gesamtausbeute dar
Tab. 2: Übersicht der Fangperioden (FP) auf den sechs Untersuchungsfl ächen. Tab. 2: Sampling periods (FP) on the study sites. 2016 2017 FP 1 FP 2 FP 3 FP 4 FP 5 FP 6 FP 7 FP 8 FP 9 14./15. 28.6. 11.7. 29.8. 3. 16.5.17 16. 29./ 30.5. 12./ 12./13. 21.8. 28.6.16 11.7.16 25.7.16 12.9.16 30.5.17 13.6.17 26.6.17 4.9.17
45 WhinCHAT II Holzinger et al - Availability of invertebrates as food for the Whinchat
Abb. 1 und 2: Malaisefalle (links) und Biozönometer (rechts) auf Fläche Nr. 5. Fig. 1 and 2: Malaise trap (le ) and biocoenometer (right) on site no. 5 (Photos: ©: L. S ).
(siehe Tab. 3). senmahd in diesem Zei enster. Im Juli erholen sich die Insektenbestände leicht, die geringsten Die Abundanzunterschiede zwischen den ein Fangzahlen gibt es Ende August. zelnen Flächen sind deutlich geringer als die Schwankungen auf einer Fläche im Jahreslauf. Bemerkenswert ist, dass die Individuenzahlen der Die höchsten Abundanzen sind in der zweiten Wirbellosen ihren Höhepunkt eindeu g Ende Mai Maihäl e anzutreff en. In der ersten Junihäl e erreichen (Abb. 1). In den 1990er Jahren wurde sinkt die Zahl um durchschni lich 38,5% und in für das Braunkehlchen im Frankenwald als mi den nächsten Wochen sinkt sie nochmals. Die lerer Legebeginn der 18. Mai (n=61) festgestellt Ursache ist wahrscheinlich die großfl ächige Wie (F 1995), d.h. die Aufzucht der Jungvögel
Tab. 3: Gesamt Fangergebnisse auf den sechs Untersuchungsfl ächen. Tab. 3: Total numbers of invertebrates sampled on the six sites within 9 sampling periods by Malaise traps and biocoenometers.
T (W .) T (D .) M B B S A [%] F K B B F 81.442 1.459 172 83.073 56,4 N M 34.120 675 179 34.992 23,8
A (E . F ) T 6.022 141 211 6.374 4,3 ( A ) C K 2.848 188 1.400 4.436 3,0 L S 4.099 66 33 4.198 2,8 S P 3.042 345 100 3.487 2,4 A Z 2.388 140 459 2.937 2,0 P A I 2.653 54 5 2.712 1,8 A S 636 123 1.412 2.171 1,5 F A 96 119 859 1.074 0,7 S P 1.024 25 0 1.049 0,7 H W 445 56 31 532 0,4 O W 78 18 53 149 0,1 S H 74 4 16 94 0,063 D O 36 2 0 38 0,026 O W 0 0 31 31 0,021 G W 0 0 18 18 0,012 S 138.953 3.415 4.997 147.365 100,0
46 WhinCHAT II Holzinger et al - Availability of invertebrates as food for the Whinchat
Abb. 3: Jahresverlauf der pro 14 tägigem Fangintervall festgestellten Wirbellosen Individuenzahlen in den Malaisefallen in aktuell besetzten und ehemals, verlassenen Braunkehlchenrevieren. Die Werte für die ak tuell besiedelten Flächen (1, 2, 3) sind als durchgezogene Linie dargestellt, unterbrochene Linien stellen die Werte für aktuell verwaiste Reviere (4, 5, 6) dar. Die Mi elwerte der jeweils drei Flächentypen werden punk ert dargestellt (blau = ja, durch Braunkehlchen besetzt; rot = nein, verwaistes Braunkehlchenrevier). Fig. 3: Numbers of Invertebrates sampled in course of the year by Malaise traps in recent and former Whinchat habitats. Recent habitats (sites 1, 2, 3) are shown in con nuous lines, discon nuous lines show former habitats (sites 4, 5, 6). Mean values are do ed lines (blue = with Whinchat, red = without). und der damit verbundene erhöhte Nahrungsbe et. al 2017). Die Autoren legen dar, dass die darf fi el hier vornehmlich auf den Juni. In diesem Bestandseinbrüche von Invertebraten nach der Monat ist aber die Individuenzahl der Wirbello Mahd durch die vorzei ge Anlage von Brachen sen im Moment gegenüber Ende Mai teilweise und Frühmahdstreifen teilweise aufgefangen um über 50% geringer. Hierbei ist anzumerken, werden können. Durch die Brachen werden Re dass die extensive Mähnutzung naturschutzfach fugialräume geschaff en, die eine bessere Über lich wertvoller Lebensräume, gem. Bayerischen winterung von Invertebraten und stärkere darauf Vertragsnaturschutzprogramm, zu ausgewählten folgende Ausbreitung im Frühjahr ermöglichen. Terminen ab dem 01.06. erfolgt. Dass es bei den Zur Nahrungsverfügbarkeit stellt sich zudem verschiedenen Mahdterminen nega ve Korre die Frage, ob sich eventuell durch eine verän la onen mit der Invertebraten Vielfalt und der derte landwirtscha liche Nutzung oder durch Biomasse der Insekten gibt, belegt eine Untersu klima sche Veränderungen die Phänologie der chung des LfU aus dem Königsauer Moos (M Nahrungsverfügbarkeit für das Braunkehlchen
47 WhinCHAT II Holzinger et al - Availability of invertebrates as food for the Whinchat verschlechtert hat? Ist das Braunkehlchen in der Weitere Ergebnisse der Untersuchung fi nden Sie Lage seinen Brutzeitraum an die möglicherweise unter/For further informa on on this project, veränderte Situa on anzupassen? Inwieweit die see: Brutphänologie des kleinen Wiesenbrüters mit Holzinger WE, Siering M, Feulner J, Fröhlich D, Gunczy der Nahrungsverfügbarkeit korreliert, sollte da LW, Huemer S, Schlosser L 2017: Quan fi zierung von her als eine mögliche Ursache für den Rückgang wirbellosen Tierarten als Nahrungsgrundlage für das der Art in Zukun näher untersucht werden. Braunkehlchen auf der Bad Stebener Rodungsinsel im Landkreis Hof, Oberfranken. Untersuchung in den Jah Auswertungen der Biozönometer Daten zeigen, ren 2016 – 2017. Bayerisches Landesamt für Umwelt dass es zwar deutliche Schwankungen der In (Hrsg.), 49p. dividuenzahlen zwischen den Flächen und Un tersuchungszeiträumen gibt, diese jedoch nicht mit der Präsenz/Absenz des Braunkehlchens in Literatur diesen zwei Untersuchungsjahren in Zusammen hang stehen. Feulner J 1995: Zur Popula onsökologie des Braun kehlchens ( Saxicola rubetra) in der Teuschnitzaue, Aufgrund des generellen Verlusts an Insekten Landkreis Kronach. Zulassungsarbeit (LA RS) am Lehr Biomasse in den letzten Jahrzehnten (z.B. H stuhl für Tierökologie I der Universität Bayreuth, 89pp. et al 2017) ist dennoch davon auszugehen, Hallmann CA, Sorg M, Jongejans E, Siepel H, Hofl and dass die verringerte Nahrungsverfügbarkeit auf N, Schwan H, Stenmans W, Müller A, Sumser H, Hörren Landscha sebene ein wesentlicher Faktor für die T, Goulson D, De Kroon H 2017: More than 75 percent Popula onsgrößenabnahme des Braunkehlchens decline over 27 years in total fl ying insect biomass in ist. protected areas.— PLoS ONE12(10), e0185809. h ps://doi.org/10.1371/journal.pone.0185809 Maßnahmen zur A rak vitätssteigerung von Flä chen als Brutreviere der kleinen Wiesenbrüterart Liebel H 2015: 6. landesweite Wiesenbrüterkar erung (z.B. Sitzwarten) sind zweifelsfrei dazu geeignet, in Bayern 2014/2015 Bestand, Trends und Ursachen analyse.— Bayerisches Landesamt für Umwelt (Hrsg.) den Rückgang kurzfris g anzuhalten. Längerfris UmweltSpezial, 126 p. g wird es allerdings von entscheidender Bedeu tung sein, die Insektendichten durch Diversifi Maczey N, Siering M, Tillmann T 2017: Quan fi zierung zierung der Landnutzung großfl ächig (nicht nur des Nahrungsangebotes für Wiesenbrüter im König sauer Moos. Faunis sche Erfassungen (Arthropoden auf Einzelfl ächen) wieder erheblich zu erhöhen. fauna). Bayerisches Landesamt für Umwelt (Hrsg.) Neben tradi oneller extensiver Grünlandnut UmweltSpezial, 72 p. zung (ein bis zweischürige Mahd) sind weitere extensiv genutzte Flächen erforderlich. Eine aus Nickel H, Reisinger E, Sollmann R, Unger C 2016: fachlicher Sicht sinnvolle Maßnahme wären ex Außergewöhnliche Erfolge des zoologischen Arten schutzes durch extensive Ganzjahresbeweidung mit tensiv genutzte Gewässerrandstreifen mit einer Rindern und Pferden: Ergebnisse zweier Pilotstudien Mindestbreite von 5 m breiten Streifen beidseits an Zikaden in Thüringen, mit weiteren Ergebnissen zu aller stehenden und fl ießenden Gewässern (gem. Vögeln, Rep lien und Amphibien. — Landscha spfl e §38 Abs. 3 WHG.), der nicht in allen Bundeslän ge und Naturschutz in Thüringen 53, 5–20. dern gesetzlich verbindlich ist (vgl. Art. 21 Bay Rödl T, Rudolph BU, Geiersberger I, Weixler K, Görgen WG). A 2012: Atlas der Brutvögel in Bayern. Verbreitung Zur Steigerung der Insektenbiomasse und Vielfalt 2005 bis 2009. Eugen Ulmer, Stu gart. der Invertebraten wird zudem die Einrichtung ei Rudolph BU, Schwandner J, Fünfstück HJ 2016: Rote nes oder mehrerer großfl ächiger Gebiete mit ex Liste und Liste der Brutvögel Bayerns, Stand 2016.— tensiver Ganzjahresbeweidung (z. B. N et al Bayerisches Landesamt für Umwelt, 30p. 2016) im Bericht des LfU (H et al 2017) vorgeschlagen.
Author’s addresses: W H , L S , S H , L W G , D F ; ÖKOTEAM – Ins tut für Tierökologie und Natur raumplanung, Bergmanngasse 22, A 8010 Graz, Austria, [email protected], offi [email protected] M S , Gereutplatz 1, D 82031 Grünwald, Germany, [email protected] J F , Walberngrün 24, D 95356 Grafengehaig, Germany, [email protected]
48 WhinCHAT II Liebel & Goymann - Whinchats in the Murnauer Moos
Improving Whinchat habitats in the Murnauer Moos, Germany
D O G P M P I O
H T. L (Garmisch Partenkirchen, Germany) W G (Seewiesen, Germany)
L HT, G W 2017: Improving Whinchat habitats in the Murnauer Moos, Germany. WhinCHAT 2, 49 55.
The Murnauer Moos is the largest, more or less intact wetland and bog in Central Europe with a formerly large popu la on of whinchats ( Saxicola rubetra). Even though a large part of the area is protected as nature reserve and Natura 2000 site, whinchats have disappeared from many of their former territories. To support the local popula on, meadow stripes of varying forms and dimensions were le uncut in 2016. In the following breeding season, the number of whin chats holding territories in one of the monitored areas increased by one third compared to 2016. Whinchats preferred fallow stripes for nes ng and had a high breeding success in the study area in 2017, presumably due to the presence of fallow stripes in combina on with favorable weather condi ons.
The Murnauer Moos – a whinchat’s paradise? basin are covered with swamps, bogs and wet grasslands which tradi onally have been one The Murnauer Moos (district Garmisch Parten of the core areas for whinchats ( Saxicola rube kirchen, Bavaria, Germany) is part of the nort tra) in Bavaria. B (1989) men ons that in hern foothills of the Alps at an al tude of 640 the 1980’s the highest whinchat densi es were to 717m a.s.l. (see Fig. 1). It consists of a diver found outside the nature reserve in extensively se natural landscape in a triangular basin (about used grasslands. Since then, land use has dras 45km²) between two alpine mountain chains in cally changed: areas in the surroundings of the the south east and south west and a hilly border nature reserve have turned into intensively used, in the north. fer lized meadows that are cut several mes du Within the Murnauer Moos, areas with the high ring the year, and large areas within the core area est values for nature conserva on have been of the wetland are no longer cut at all. As a con protected as nature reserve (23,78km²); in addi sequence, bushlands and dense reed beds have on there are special protected areas for birds developed during the last decades. Both of these (42,94km²; SPA, Natura 2000). Large parts of the developments have reduced the habitat quality
Fig. 1: Basin of the Murnauer Moos seen from mount Heimgarten towards northwest (Photo: © Heiko T. L ).
49 WhinCHAT II Liebel & Goymann - Whinchats in the Murnauer Moos
300 250 250
200 170
150 132
100 75 Breeding pairs pairs Breeding 50
0 1977 1980 2005 2016
Fig. 2: Popula on decline of whinchats in the Murnauer Moos (B L 1978, database at LfU; W 2016; in case of ranges the lower number was used). for whinchats and are in part responsible for the nitoring and designing specifi c measures to sup local decline of whinchats (see Fig. 2). port whinchats in the area. The mapping project of W (2016) provided us with an ideal basis A mapping project of grassland birds of the whole to survey the success of these measures. area in 2016 ( W 2016) showed that the once large whinchat popula on had dropped by more than 50% since 1977 and consisted of only 75 95 Measures to improve habitats breeding pairs in 2016. The remaining popula on is mainly founded on wet grassland areas within At the southern end of lake Ammersee (districts the nature reserve that are cut only once a year Weilheim Schongau and Landsberg am Lech) fal and not before September 1 st . low stripes have been used to a ract whinchats when arriving from their wintering grounds by The overall decline of whinchats in Bavaria (L off ering natural perches for hun ng and singing. 2015, R et al 2016) in combina on While these measures had been successful in with the dras c popula on crash in the Murnau recrui ng whinchats during the fi rst couple of er Moos mo vated us to engage in a closer mo years (C. N , pers. comm.), recent
Fig. 3: Digi zing of fallow stripes in winter (Photo: © Heiko T. L ).
50 WhinCHAT II Liebel & Goymann - Whinchats in the Murnauer Moos years have seen a new decline in whinchats, farmers using a GPS device to avoid fi nes in case even though the habitat seems to be suitable (R. uncut areas should have exceeded the 20% limit G , pers. comm.). of uncut area. Impressed by the (at least) ini al success of the measures at lake Ammersee, farmers of the Mapping of territories and breeding success Murnauer Moos area were encouraged to leave In spring 2017, territories of whinchats were parts of their grasslands uncut, thereby crea ng mapped in two important subareas for whin fallow stripes of old uncut grassland. In the Ba chats the Weidmoos and the Niedermoos. varian system of contractual nature conserva on (i.e. “Vertragsnaturschutzprogramm”) farmers Weidmoos can leave up to 20% of their grasslands uncut In the Weidmoos territories were mapped twice, without fi nancial reward. Another possibility of on May 5 th and June 9 th , 2017 in a project area co fers them fi nancial compensa on if they leave vering 73ha, both mes without leaving the car 5 20% of their meadows uncut and thus crea to avoid disturbing the last pair of breeding Eura te obligatory fallow stripes. In both cases fallow sian Curlews ( Numenius arquata) in the Murnau stripes must not be established in the same area er Moos. Mapping un l May 21 st might be infl u between years; instead diff erent areas need to enced by migra ng individuals as demonstrated be selected and le uncut in subsequent years. by G (2012). The results indicate an In 2016, the district started to promote the esta increase in whinchat territories by about one blishment of fallow stripes among farmers that third compared with the previous year (W had contracts within the core areas for whin 2016). In 2016 there were only two or three chats. Members of the District Offi ce helped small fallow stripes. In 2017, an area of 3.6ha
Fig. 4: Comparison of whinchat territories at Weidmoos 2016 with few and 2017 with several fallow stripes (note: northern and southernmost areas of the project area were not covered well due to long observa on distance from the car).
51 WhinCHAT II Liebel & Goymann - Whinchats in the Murnauer Moos
Fig. 5: Female whinchat at Murnauer Moos in spring 2017 (Photo: © Heiko T. L ). were le uncut (about 5% of the grasslands). The se led at the border of the adjacent large reed stripes were of varying forms and contained a beds that surround the project area in the north, varying amount of reed ( Phragmites australis), west and south. which whinchats used as perches. Most stripes The popula on density within the project area were at least fi ve meters wide. Obviously, whin was 2.3 territories/10ha in 2017 compared to chats used the fallow stripes in this subarea as 1.6 territories/10ha in 2016. Hence, the popula song posts and in 2017 were more likely to se le on density was s ll much lower than densi es within the large meadow. In 2016, they mainly in ideal habitats managed with fallow stripes at
Fig. 6: Narrow fallow stripes at Niedermoos (Photo: © Heiko T. L ).
52 WhinCHAT II Liebel & Goymann - Whinchats in the Murnauer Moos
Federsee (Baden Wür emberg), for example, ons (e.g. LBV) or the District. In 2016, a farmer where 6 territories/10ha are reached in nutrient le narrow stripes of the meadow unmown af poor and sedge rich meadows (E 2006, ter every turn that he did with his tractor (Fig. 2015). At the Tyrolean hot spot for whinchats in 6). The result were more than 60 narrow fallow the Ehrwald basin (35km southwest of Murnauer stripes of about one meter width. During spring Moos; A. S 2017, pers. comm.) migra on in April we observed that many whin popula on densi es of 4.5 territories/10 ha are chats used these narrow fallow stripes as hun ng also higher than within the best subareas within perches. the Murnauer Moos. During later visits in June, The mapping of whinchats in this area of narrow several juvenile whinchats could be observed fallow stripes did not demonstrate an increase within the Weidmoos, indica ng that whinchats in number of whinchat territories between 2016 successfully bred within the area. and 2017, possibly because of the nutrient poor humid meadows that lack plant species that grow Niedermoos high enough to serve as perches for the chats. Niedermoos is one of three study areas where However, intense search for nests and follow up the Max Planck Ins tute for Ornithology inves observa ons showed that the structures were gates breeding success, interac ons and com used for reproduc on. A total of 17 nests was pe on between whinchats and stonechats ( Sa found (Fig. 7), with ten of them located in fallow xicola rubicola). The site was chosen, because it stripes (Fig. 8), three at the border to permanent is an important breeding area for both species. fallow areas that are dominated by reed, three Further, measures to improve habitat quality can further nests were within the mown meadow, be realized in this loca on, as a large frac on of and one nest below a bunch of old mown grass the area is owned by nature protec on organiza
Fig. 7: Breeding success of whinchats at Niedermoos 2017. Note that the loca on of fallow stripes is only indicated for the project area, there were further unmapped fallow stripes within the rest of the area.
53 WhinCHAT II Liebel & Goymann - Whinchats in the Murnauer Moos
Fig. 8: Nest of whinchats in a fallow stripe (Photo: © Wolfgang G ). that had remained in the meadow. Three nests ber of 72 juvenile whinchats fl edged. Also one of were depredated by unknown predators, but the other main grassland birds in the area, the two of the aff ected pairs immediately produced meadow pipit ( Anthus pratensis ) used the fallow a replacement clutch and successfully bred in stripes for nes ng. their second a empt. A surprisingly large num
Fig. 9: Late fl owering plants (like Gen ana pneumonanthe in the foreground) and insects benefi t from fallow stripes as well (Photo: © Heiko T. L ).
54 WhinCHAT II Liebel & Goymann - Whinchats in the Murnauer Moos
Conclusions Literature Fallow stripes had a posi ve eff ect to a ract Bezzel E 1989: Die Vogelwelt des Murnauer Mooses: whinchats within the study areas in the Murnau Erfolgskontrolle der Ausweisung eines Naturschutzge er Moos. Compared to other breeding sites bietes. Schri enreihe des Bayerischen Landesamtes of whinchats elsewhere, it is obvious that the für Umweltschutz 95, 61 78. densi es reached within the Murnauer Moos Bezzel E, Lechner F 1978: Die Vögel des Werdenfelser are s ll below the poten al for whinchats. The Landes. Kilda Verlag, Greven. comparison of whinchat territories in the Weid moos between 2016 and 2017 clearly shows that Einstein J 2006: Bestandsentwicklung, Habitat und temporary fallow structures and the presence of Schutz des Braunkehlchens ( Saxicola rubetra) am Fe perches may be the domina ng limi ng factors dersee. Ornithologische Jahreshe e für Baden Würt for suitable whinchat habitat within this part of temberg 22, 175 188. the Murnauer Moos. Fallow stripes may not only help to increase breeding densi es of whinchats, Einstein J 2015: Das Braunkehlchen ( Saxicola rubetra) they may also represent important hun ng per am Federsee: Bestandsentwicklung, Habitatwahl und ches for migrants passing through, i.e. a measu Schutzmaßnahmen. In: Bas an HV, Feulner J (Eds.): Living on the Edge of Ex nc on in Europe. Proc. 1st re to improve migratory connec vity. Further, European Whinchat Symposium, 293 294. LBV Hof, because whinchats preferen ally chose fallow Helmbrechts. stripes as nes ng sites, they could poten ally be a racted to more intensely farmed areas (i.e. Geiersberger I 2005: Landscha sveränderungen im meadows that are cut more o en), if they would Murnauer Moos und ihre Auswirkungen auf die Vo off er such stripes with safe nes ng possibili es. gelwelt. Unveröff . Gutachten im Au rag des bayeri Of course, such measures also depend on other schen Landesamts für Umwelt, 74p. factors, i.e. a suffi cient insect density in more in tensely farmed areas will be required to success Liebel HT 2015: Bestandstrend des Braunkehlchens fully raise a brood. und anderer Wiesenbrüter in Bayern. In: Bas an HV, Feulner J (Eds.): Living on the Edge of Ex nc on in The aim of this contribu on is to publicly pro Europe. Proc. 1st European Whinchat Symposium, 45 mote the posi ve eff ect of fallow structures for 54. LBV Hof, Helmbrechts. whinchats and to promote contracts including obligatory fallow stripes in nutrient poor exten Rudolph BU, Schwandner J, Fünfstück HJ 2016: Rote sive grasslands during the contract nego a ons Liste und Liste der Brutvögel Bayerns. Online: h ps:// www.lfu.bayern.de/natur/rote_liste_ ere/2016/doc/ with local farmers that par cipate in the contrac voegel_infobla .pdf [07.08.2017] tual nature conserva on program. Weiß I 2016: Monitoring und Artenhilfsmaßnahmen ausgewählter Wiesen und Schil rüter im Murnau er Moos und den Loisachmooren. Brutsaison 2016. Unveröff . Gutachten im Au rag des Landratsamtes Garmisch Partenkirchen, 80p.
Author´s addresses: H T. L , L G P , U N , Olympiastraße 10, D 82467 Garmisch Partenkirchen, heiko.liebel@lra gap.de W G , M P I O , Eberhard Gwinner Str. 6a, D 82319 Seewiesen, [email protected]
55 WhinCHAT II Gray, Copland, Kenny & McMahon - Delayed mowing in Ireland
Tackling conserva on challenges from the ground up: delayed mowing for the Whinchat
UCD S A F S B W I A G (Dublin, Ireland), A S. C (Banagher, Ireland), K K (Dublin, Ireland) B J. M M (Dublin, Ireland)
G A, C AS, K K, M M BJ 2017: Tackling conserva on challenges from the ground up: delayed mowing for the Whinchat. WhinCHAT 2, 56 57.
Agricultural intensifi ca on is comparable and breeding yet they are also hugely culpa to deforesta on and anthropogenic climate ble in their demise. change as one of the greatest threats to bio diversity across the globe. The twin challen For the ground nes ng Whinchat, early and ges of food provision for a growing human more frequent grassland mowing throug popula on and the sustainable use of biolo hout their breeding range has likely contri gical resources con nue to plague decision buted to range contrac on and popula on makers. Agriculture and the environment declines. The fi rst European Whinchat Sym have a complex rela onship that is bound by posium 2015 concluded that the species has agriculture’s simultaneous exploita on and experienced a 50 90% decline over the last crea on of ecosystem services. Similarly, ag 20 years. Implemen ng locally led agri envi riculture systems are essen al for the survi ronmental schemes in Whinchat stronghold val of many species for food, shelter, water areas across Europe could aid the recovery of
Fig. 1: A Whinchat located on Tower Callow, a wet grassland meadow site next to the River Shannon in Ba nagher, Co. Off aly, Ireland (Photo: © Alex C ).
56 WhinCHAT II Gray, Copland, Kenny & McMahon - Delayed mowing in Ireland this bird of conserva on concern. wing can be delayed across a territory this will presumably result in popula on recruitment The Whinchat is poorly understood in Ireland and can avoid a call for delayed mowing over with this research only being the second of en re farms crea ng an environmentally and it’s kind. The Shannon Callows is the Whin economically viable conserva on op on. chats breeding popula on stronghold in Ire This work seeks to aid Whinchat popula on land and therefore an appropriate loca on recovery in Ireland, improve food availability for conserva on ac on (Fig. 1). As in Europe, for insec vores and serve as an example of a delayed mowing is urgently required to halt species targeted conserva on plan. the decline of this vulnerable species. With the Interna onal Whinchat Working According to current literature, 75.1% of Group, cross border collabora on is probab Whinchat fl edglings must survive the bree le. Whinchats are representa ve of the lar ding season if popula ons are to remain un ger agricultural biocenosis and this project changed. Delaying mowing is an expensive will provide solu ons for policy makers to incovenience for the farming community; balance agricultural usage and biodiversity therefore research into a Whinchat territory requirements, thus encouraging a more sta size is crucial to target conserva on. If mo ble agri ecosystem.
Author´s addresses: A S. C , (corresponding author), Bird Watch Ireland, Crank House, Banagher, Off aly, Ireland, [email protected] A G , K K B J. M M , UCD School of Agriculture and Food Science, University College Dublin, Belfi eld, Dublin 4, Ireland.
57 WhinCHAT II Ames - Population estimation and breeding success at RSPB Geltsdale
Popula on es ma on and breeding success of Whinchat ( Saxicola rubetra) at RSPB Geltsdale, Cumbria, UK
E A (Leigh on Sea, United Kingdom)
A E 2017: Popula on es ma on and breeding success of Whinchat ( Saxicola rubetra) at RSPB Geltsdale, Cumbria, UK. WhinCHAT 2, 58 64.
Long term monitoring of Whinchats (Saxicola rubetra) requires standardised survey eff ort and reliable popula on es mates. Distance sampling was found to underes mate the known popula on of whinchats at Geltsdale but provided a be er index than transect counts. The nega ve bias may be due to viola on of key assump ons of the distance sampling method, and diff erences in detectability between the sexes and between paired and unpaired males. Improvements to the methods could increase the accuracy of popula on es mates, but may also increase the complexity of both data collec on and sta s cal analyses. Double sampling may provide a simpler method of correc ng for bias, and could also allow measures of produc vity and therefore assessment of the impact of management strategies on breeding success.
Details of an MSc research project conducted at RSPB Geltsdale in 2016.
Introduc on The popula on of Whinchats at RSPB Geltsdale reserve has been closely monitored since 2011. For con nued monitoring to be viable and eff ec ve, rapid assessment methods which standardi se survey eff ort and provide reliable popula on es mates are needed. Popula on indices and abundance es mates of Whinchats produced by line transect surveys and distance sampling were compared with numbers from intensive surveys using a double sampling approach. Factors infl u encing detectability during transect surveys were inves gated, including sex, detec on method, breeding status, breeding stage, and incuba on ac vity. Incuba on regimes and nest survival were monitored using temperature sensors in nests.
Methods Fig. 1: A map of the study area at RSPB Geltsdale Reser ve in the North Pennines, showing the survey regions, 9 1 km line transect surveys were conducted at transect routes (T1 to T9) and whinchat territories bet Geltsdale between 2014 and 2016 (Fig. 1). Three ween 2014 and 2016. Known replacement and second visits were made to each transect: (1) 15 22 May, broods in 2016 are not shown. A 200 metre buff er on either side of each transect route shows the area co (2) 23 30 May, (3) 31 May – 7 June, between vered by each transect survey. In 2016, the survey re 05:00 and 09:00 AM. Sex and detec on method gions Bruthwaite East (BE), Bruthwaite West (BW) and were recorded on transect surveys in 2016. Di the Gairs (G) were the focus of intensive searches in stance sampling (Buckland et al 2001) was per May. In June 2016, addi onal observers enabled se formed in 2015 and 2016, and Distance so ware arching of Binney Banks (BB), Old Water (OW), New (Distance 7 Release 1, T et al 2010) used to Water (NW), Midgeholme (M), Talkin Fell (TF) and Hyde Park (HP). © Crown Copyright OS 1:50,000 Scale produce popula on es mates. Limited numbers Colour Raster 2016. An Ordnance Survey/ Edina sup of detec ons necessitated use of data from all plied service.
58 WhinCHAT II Ames - Population estimation and breeding success at RSPB Geltsdale
Fig. 2: Whinchat pair in the study area at Bruthwaite East, Transect 2 (Photo: © Stephen W ). three visits, with abundance es mated from the Results mean. Transect survey areas were also intensi Intensive sampling, transect counts and distance vely searched, and the loca ons of all whinchats sampling all detected a decrease in the whinchat recorded, including colour combina ons of all popula on between 2014 and 2016 (Tab. 1). colour ringed individuals. Territory mapping and nest fi nding methods were used to es mate the On a single transect visit, in 2016, a mean of 55% true popula on. Thermochron® iBu on® tempe of ac ve territories were detected. Summed ma rature sensors were placed in nests to record in ximum counts of males by 200 m sec on across cuba on ac vity (at 2 minute intervals for a 68 the three visits for each transect (‘Sec on ma hour period; Fig. 8) and monitor nest survival and ximum’) were more highly correlated with the preda on events (at 20 minute intervals for the number of territories es mated from intensive dura on of the nes ng period) in 2016. sampling (‘known’ territories) than means or
Tab. 1: Numbers of whinchats recorded by diff erent survey methods between 2014 and 2016. Distance samp ling es mates are given with 95% confi dence intervals (CI).
SURVEY MEASURE 2014 2015 2016 INTENSIVE S EARCH TERRITORY 52 42 35 PAIR 36 24 25 TRANSECT M AXIMUM MALE 38 28 24 FEMALE 9 5 7 SECTION M AXIMUM MALE 32 30 FEMALE 6 8 DISTANCE S AMPLING MALE 33 27 (CI 21.5-50.1) (CI 17.3 – 41.6)
0.5*(INDIVIDUAL) 18.5 17 (CI 13.1 – 26.6) (CI 11.0 – 26.2)
59 WhinCHAT II Ames - Population estimation and breeding success at RSPB Geltsdale
Fig. 3: Study area surrounding Transect 4, Bruthwaite West, RSPB Geltsdale reserve, Cumbria, UK (Photo: © Elinor A ). whole transect maxima. A calibra on factor of Males were more detectable than females. Bet 1.237, obtained from regression, was required ween 2014 2016, males made up 59.9% of the to es mate the number of territories from the popula on, but accounted for 85.6% of transect Sec on maximum number of males. Distance detec ons. In 2016, 63.3% of male detec ons sampling underes mated the known popula on, were by sound, with male song allowing detec and a calibra on factor (1.298) was required (Fig. ons over greater distances than females (Fig. 6). 5). Be er es mates of the number of territories Breeding status also aff ected detectability; un were produced using the number of males than paired males were more detectable than paired half the number of individuals (Tab. 1). Propor males. In 2016 paired males were detected sin onal changes in distance sampling es mates and ging on only 24% of the occasions they were known popula on numbers were signifi cantly known to be present compared with 80% of oc correlated; distance sampling therefore provided casions for unpaired males, and were recorded a be er popula on index than Sec on maximum singing on fewer visits than unpaired males. No counts. clear eff ect of breeding stage was found on de tectability, likely due to the small sample size and Tab. 2: Nest survival by year, 2014 – 2016, calculated study methods. using the Mayfi eld method (M 1975, J 1979). The incuba on study suggested that incuba ng females may be available for only 16% of the YEAR NEST S URVIVAL me during the transect survey period (05:00 2014 33.3% (CI 17.5 – 62.4%) AM to 09:00 AM), and less detectable during this 2015 34.1% (CI 18.6 – 61.5%) period than later in the day, but this result was 2016 78.0% (CI 62.4 – 97.3%) not signifi cant due to the small sample size (n=5; MEAN 2014-2016 49.9% (CI 38.7 – 64.2%) Fig. 7), and further studies are needed. Breeding
60 WhinCHAT II Ames - Population estimation and breeding success at RSPB Geltsdale success and nest survival were highest in 2016, fi xed along tracks in areas of known high terri and varied between years (Tab. 2). Preda on ra tory density for ease of access and repeatability. tes were low, and occurred mostly during day However, tracks may infl uence territory distribu light, in contrast to the fi ndings of T (2015) on pa erns, and avoidance of the transect line on Salisbury Plain. by whinchats would nega vely bias popula on es mates; es mates in this study were therefore limited to the area covered by the transect sur Discussion veys. Where detec on on the line is uncertain, Distance sampling provided a be er popula on for example when individuals are foraging in index than maximum counts from line transects, dense vegeta on, more complex methods such but underes mated the known popula on. This as mark recapture distance sampling, or restric may have been due to use of mean rather than ng detec on to audible cues such as male song maximum counts, and possible viola ons of key could be used to address this (B et al distance sampling assump ons: that distance 2015). Undetected evasive movement of indivi measurements are exact; individuals are dis duals would also cause nega ve bias in the po tributed independently of transect lines; indi pula on es mates; this should be minimised by viduals on the line are detected with certainty; scanning well ahead and adjus ng the speed of and individuals are detected at their ini al loca travel to detect individuals before they are distur on (B et al 2001, T et al 2010). bed (B et al 2001, 2015). Mul ple cova Overes ma on of distances would nega vely riate distance sampling could be used to account bias es mates (B et al 2001), and use for varia on in detec on probabili es between of laser range fi nders or recording distances in categories such as males and females, or diff e bands could increase accuracy in future surveys rent detec on methods (S G (B et al 2015). The transect routes were 2009, B et al 2015). Availability models
Fig. 4: Study area surrounding Transect 5, The Gairs, RSPB Geltsdale reserve, Cumbria, UK (Photo: © Elinor A ).
61 WhinCHAT II Ames - Population estimation and breeding success at RSPB Geltsdale
12
30% 10 y = 0.7702x 8 R² = 0.6065 20%
6
4 10% % Time off nest % Time off
2 0%
DISTANCE es number of males mated es DISTANCE 05:00 09:00 12:00 17:00 21:00 0 0 2 4 6 8 10 Time period Known number of territories Fig. 7: The percentage of me spent off the nest by Fig. 5: The rela onship between the es mated num female whinchats in 4 hour me periods through the ber of territories generated from Distance analysis and day. The fi rst period, from 05:00 to 09:00 AM, was the the number of known territories found during inten me during which transect surveys were undertaken. sive searches in each of the one kilometre transect Timings were obtained from iBu ons which recorded areas in 2015 and 2016. Es mates for the number of nest temperatures at 2 minute intervals for 48 hours territories were generated from the number of males in fi ve nests. Bars are ± 1 standard error. Assuming cor using means of the three transect visits. rect iden fi ca on of arrival and departure events from temperature data, departure and arrival mes were accurate to ± 2 minutes; the overall dura on of each Detec on method on or off bout was therefore accurate to ± 4 minutes. Seen Heard The diff erence between the me periods, though no 6 table, is not signifi cant, likely due to the small sample 5 size: Friedman’s 2 way ANOVA H=6.918, df=3, p=0.075, 4 Male Female n=5. 3 2 1 males. A measure of the propor on of unpaired 0 males, or an addi onal measure of breeding ac 6 vity such as the presence of females, nests or 5 4 behaviour indica ng young would therefore be 3
Number of observa ons Number of observa desirable to avoid overes ma ng the breeding 2 popula on. 1 0 A greater sampling eff ort and more comprehen 0 50 100 150 200 250 0 50 100 150 200 250 sive environmental data is needed to fully inves Perpendicular distance from transect line (10m intervals) gate the preliminary fi ndings of the incuba on study. iBu ons were found to be frequently re Fig. 6: Distribu on of whinchat observa ons in 2016, in 10m distance intervals from the transect line, for moved from nests, and methods were needed males and females, and for diff erent methods of de to prevent this. Suscep bility to brood parasi tec on. The detec on method refers to the way in za on by common cuckoo Cuculus canorus may which each whinchat was fi rst iden fi ed by the obser encourage removal of foreign objects from nests; ver. Individuals were o en seen a er fi rst being heard, careful fi xture and camoufl age of iBu ons are or heard to sing or call a er fi rst being seen. For males, therefore recommended in future studies to avo detec on by sound includes both song and calls, whe reas for females this refers only to calls. id impacts on incuba on behaviour (S et al 2015). High nest survival demonstrates the po and mul pliers may also need to be considered if ten al for high produc vity at Geltsdale and the incuba ng females are to be included in the ana importance of this site for breeding whinchats, lysis ( B et al 2015). The higher detecta but as considerable varia on can occur in preda bility of unpaired males could also mask the true tor ac vity and nest survival between years, lon extent of popula on declines (M et al ger term studies are needed. Con nued monito 2016), especially if restric ng surveys to singing ring of produc vity would enable an assessment
62 WhinCHAT II Ames - Population estimation and breeding success at RSPB Geltsdale
of the impact of management strategies and ef and random placement of transects throughout forts to reverse current popula on declines. the study area. More complex methods such as incorpora ng measures of cue frequency in Conclusion males and female detectability during incuba on in availability models, and mark recapture By accoun ng for varia on in detectability, dis distance sampling to es mate detectability on tance sampling provides a more reliable index the transect line could further improve es ma than maximum counts from line transects, and tes but would require more advanced sta s cal may be suffi cient for detec ng declines and mo methods and data collec on and would be more nitoring the overall popula on trend. However, me consuming and resource intensive. If an ac as an es mator of absolute abundance, distance curate abundance es mate is required, unless sampling as conducted here suff ers from a con such improvements signifi cantly reduce the bias siderable nega ve bias, indica ng probable vio of distance sampling es mates, it may prove sim la on of key assump ons and other signifi cant pler and more cost eff ec ve to derive a calibra infl uences on detectability such as sex and bree on factor from an intensively sampled subset of ding status. The accuracy of distance sampling survey plots in a double sampling approach (B es mates may be improved with some simple al E 2002, C 2007), simultaneously tera ons to the methods used in the present stu providing the opportunity to record breeding sta dy, including increasing the accuracy of distance tus and produc vity and enabling an assessment measurements by recording in distance intervals of the impact of management strategies and ef or using laser range fi nders; including sex and forts to reverse current popula on declines. detec on method as covariates in the models;
40
35
30
25
20
Temperature [°C] Temperature 15
10 21:00 00:00 03:00 06:00 09:00 12:00 15:00 18:00 21:00 00:00 03:00 Time Nest A Ambient Twilight Dark Nest B temperature
Fig. 8: Example temperature data from two whinchat nests collected over a 30 hour period from 28th to 30th June 2016. Temperatures were recorded at 2 minute intervals using iBu ons placed in the nest cups. Ambient tempera ture is given for comparison, along with hours of twilight and darkness as defi ned by (a) sunset, (b) dusk, (c) dawn, and (d) sunrise. A sharp decrease in nest temperature indicates departure of the female from the nest (1), with a sharp increase in temperature on her return (2). Small temperature varia ons (3) were assumed to be due to beha viour at the nest. Nocturnal varia ons in temperature were evident (4), but the minimum temperatures reached at night were less severe than those recorded during the day (5) sugges ng nocturnal presence of the female at the nest, but reduced contact with nest contents. Mean, minimum and maximum nest temperatures diff ered between nests. A minimum temperature change threshold was selected for each nest based on the overall range in nest temperatures to aid in the iden fi ca on of departures; 4 and 1.5 °C for nests A and B respec vely. There were some diffi cul es in interpre ng the data during periods of less regular behaviour (6) especially when compared with noc turnal varia ons. Pa erns of behaviour varied through the day, with more me spent on the nest in the fi rst hours a er sunrise. In this example, departures from both nests show increased regularity in the a ernoon and evening (7). These nests were located less than 5 km apart, and would have been subject to similar weather condi ons.
63 WhinCHAT II Ames - Population estimation and breeding success at RSPB Geltsdale
Acknowledgements Johnson DJ 1979: Es ma ng nest success: the May fi eld method and an alterna ve. The Auk 96, 651 661. Thanks to my two supervisors, Dr Ian Hartley (Lancaster University) and Stephen Westerberg Mayfi eld HF 1975: Sugges ons for calcula ng nest (RSPB Geltsdale), for all their support and ad success. The Wilson Bulle n, 456 466. vice; to Amanda Proud and Mar n Ketcher for Morrison CA, Robinson RA, Clark JA, Gill JA 2016: Cau assistance with ringing, nest fi nding and territory ses and consequences of spa al varia on in sex ra os mapping; to John Callion for nest fi nding; and to in a declining bird species. Journal of Animal Ecology the RSPB at Geltsdale for accommoda on during 85(5), 1298 1306. the fi eldwork. Smith JA, Cooper CB, Reynolds SJ 2015: Advances in techniques to study incuba on. In: Deeming DC, Rey Literature nolds SJ (Eds): Nests, Eggs and Incuba on. Oxford Uni Bart J, Earnst S 2002: Double sampling to es ma versity Press, Oxford. te density and popula on trends in birds. The Auk Stanbury A, Gregory R 2009: Exploring the eff ects of 119(1), 36 45. truncated, pooled and sexed data in distance samp Buckland ST, Anderson DR, Burnham KP, Laake JL, Bor ling es ma on of breeding bird abundance. Bird Stu chers DL, Thomas L 2001: Introduc on to distance dy 56(3), 298 309. sampling: Es ma ng abundance of biological popula Taylor J 2015: Determinants of varia on in produc ons. Oxford University Press, Oxford. vity, adult survival and recruitment in a declining mi Buckland ST, Rexstad EA, Marques TA, Oedekoven CS grant bird: the Whinchat ( Saxicola rubetra) (Doctoral 2015: Distance sampling: methods and applica ons. disserta on, Lancaster University). New York, Springer. Thomas L, Buckland ST, Rexstad EA, Laake JL, Strind Collins BT 2007: Guidelines for using double sampling berg S, Hedley SL, Bishop JR, Marques TA, Burnham in avian popula on monitoring. The Auk 124(4), 1373 KP 2010: Distance so ware: design and analysis of dis 1387. tance sampling surveys for es ma ng popula on size. Journal of Applied Ecology 47(1), 5 14.
Author´s address: E A , 9 Bailey Road, Leigh on Sea, Essex SS9 3PJ, United Kingdom, [email protected].
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