tussenDuin & Dijk

Connection and defragmentation

Nature in Noord-Holland. Volume 17 3 ● 2018 Edo Goverse, Geert Timmermans, Erik de Haan & Luc Hoogenstein

Noord-Holland welcomes the otter The otter was successfully reintroduced in the in 2002-2008. The province of Noord- Holland realised that the otter will settle in the region in the future and has taken defragmentation measures. This paid off in 2016, with an otter sighting at one of the N236 wildlife passages between the Ankeveense Plassen and the Naardermeer.

History vermin, but rather furred game. 20% of the Dutch otter population Around 1900, the otter (Lutra lutra) Moreover, in large parts of the falling victim to traffic (Lammerts- was a relatively common occur- Netherlands, otters were no longer ma & Niewold, 2016). rence in the Netherlands and even being hunted, which allowed for considered a pest. This was not a gradual recovery of populations A comeback? only due to the animals’ fish-cen- to occur. Between 1945 and 1962, Between 2002 and 2008, the otter tred diet, but also because of the the otter was only found in six atlas was successfully reintroduced in damage they could cause to fish blocks in the Vechtplassen area. In the Netherlands. A steady recoloni- traps. Bounties were paid for the 1979 an otter was sighted in the sation can be observed throughout destruction of otters, and otter fur, wild in the Naardermeer for what the Netherlands (figure 2). Having too, was much in demand. Even was probably the last time. For the been absent from Noord-Holland Artis at the time would ‘order’ an 1982-1988 period, the Atlas van for 24 years, on 11 June 2010 an annual delivery of otters from the Nederlandse Zoogdieren (Veen & otter was captured by a wildlife Naardermeer to supplement the zoo Broekhuizen, 1992) mentions three camera in the Vechtplassen area population, which was seen as very atlas blocks in Noord-Holland, with (Van den Akker & Harder, 2010). normal. Even so, writings from as definite sightings in Waterland and Despite an intensive camera-trap early as 1864 mention a population one in De Botshol (Utrecht), which study aimed at also detecting pine in decline (Veen & Broekhuizen, is an atlas block that overlaps with martens (Martes martes) in this 1992). Van Wijngaarden and Van de Noord-Holland. The latter report area, this sighting was to be the Peppel (1970) retraced the preva- is from 1986 (Nolert & Martens, only one. On 5 September 2011, a lence of otters in the Netherlands 1989). Not much later, by 1989, road kill victim was found (‹) by across different periods in history. the species seems to have disap- the side of the Bloklaan (N403) in Around 1900, the otter was preva- peared completely (Lammertsma & Loosdrecht. lent in approximately sixty of the Niewold, 2016). The otter popula- During major road works in 2013, Noord-Holland atlas blocks (5x5 tion’s deterioration was caused by a two wide wildlife passages under km2) (figure 1). The second half combination of several factors that the N236 were created to connect of the nineteenth century saw a con- have been since been reported on the Naardermeer and Vechtplassen tinued steady decline, and mentions extensively. Habitat fragmentation nature reserves, among other inten- of ‘rare occurrences’. By 1942, and road fatalities are currently im- tions hoping to create a safe place otters were no longer considered portant factors in this regard, with for animals to cross. A camera-trap

12 ● 3 ● The wildlife passage under the Gooilandseweg (N236) where the otter was captured by the wildlife camera on 4 November 2016. Photo: Geert Timmermans.

Noord-Holland welcomes the otter

● Figure 1. The geographical distribution of the otter circa ● Figure 2. Otter observations (the red dots) after 1900 (from Van Wijngaarden & Van de Peppel, 1970). reintroduction in the Netherlands in 2002 (© NDFF).

study has shown that foxes (Vulpes this site, the banks of both pro- Ankeveense Plassen vulpes), pine martens and roe deer vinces are a mere 300 metres apart. Between 8 October and 6 Novem- (Capreolus capreolus) have been On 20 March, 30 October and 18 ber, a wildlife camera was in place crossing there right from the start. December 2016 and 4 February, 24 close to the new wildlife passages October and 23 December 2017, the under the Gooilandseweg (N236, Hollandse Brug group searched in vain for tracks – photo). The camera had been posi- At the annual gathering of the Be- in the context of the NEM Versprei- tioned along the ditch delineating ver- en Otterwerkgroep CaLutra on dingsonderzoek Otter (the national the adjacent pasture. This again 12 March 2016, taking place at the Ecological Monitoring Network resulted in a great many photo- Ankeveense Plassen, the working study monitoring the presence of graphs of rippling water, brown rat, group split up into small groups to otters). The absence of spraints does roe deer and birds. One of the very look for traces of otters. Under the not necessarily imply the absence of last photos, taken on 4 November expert guidance of an experienced otters: if there are no conspecifics (photo), however, revealed an otter. tracker they were able to find a in the area, the otters will have Between 13 November and 10 De- fresh otter print near the Hollandse no reason to mark their territory. cember 2016, three cameras were Brug in Muiderberg. They also In December 2016, two wildlife in place along that same ditch, this came across some old spraints cameras were installed. This result- time failing to capture any sign of (otter faeces) on the basalt blocks ed in 20,000 photographs mainly an otter. Natuurmonumenten sub- on the banks of the lake. The otter featuring waves, brown rat (Rattus sequently ventured further into the is widespread in and at norvegicus) and some birds. Ankeveense Plassen area to place ▶

3 ● 13 least twenty cameras will be used. A subset of the cameras will be installed at fixed locations in and around the areas, others will be ● The first otter was caught on camera near the N236 used flexibly and moved from time wildlife passages on 4 November 2016. Photo: Edo to time. This combination is meant Goverse & Geert Timmermans. to provide an insight into where otters actually occur and clarify in which ways they use the region and whether there are any problematic cameras there. They did manage to at the Afsluitdijk for instance, areas or bottlenecks. Finding signs capture an otter there on 24 some years ago. Spraints have been of reproduction, of course, would November 2016. Meanwhile, wild- found on the Houtribdijk, connect- be even better. In early October life cameras permanently mounted ing and Enkhuizen, and 2017, the first cameras were put in under the two passages have (as yet) the Nieuwkoopse Plassen area in place. During the winter period, failed to capture any otters; see the Zuid-Holland now has an estab- the general focus will be on finding article ‘Online monitoring through lished otter population. Odds are spraints and, in case of snowfall, wildspotter.nl’ in this same edition that they actually travelled through prints. Until now (June 2018) this (Van Heukelum & Van den Dries, Noord-Holland on their way there. had not led to any new observa- tions. Good news: no roadside casualties have Edo Goverse, [email protected] been reported so far. Geert Timmermans g.timmermans@.nl 2018). From 7 October 2017, the Recurring camera trap observations Erik de Haan, Natuurmonumenten same pasture fencing post was fitted in the Vechtplassen area would seem e.dehaan@n atuurmonumenten.nl with another wildlife camera, that to suggest that otters have already Luc Hoogenstein, Natuurmonumenten over twelve days did not capture any settled in Noord-Holland as well. [email protected] sign of otters. What is also good news is that no roadside casualties have been Naardermeer reported so far. Nonetheless, the With the above in mind, Natuur- region will continue to be extremely Reference literature monumenten decided to install dangerous for otters so long as no ● LAMMERTSMA, D.R. & F.J.J. NIEWOLD, 2016. De otter. P. 247-249 in: Broekhuizen wildlife cameras in the Naardermeer measures have been taken to prevent S., K. Spoelstra, J.B.M. Thissen, K.J. Canters nature reserve as well. On 12 and 13 animal casualties on busy provincial & J.C. Buys (red.). Atlas van de Nederlandse March 2017, that decision paid off roads. The provincial government is zoogdieren. Natuur van Nederland deel 12. when an otter was caught on cam- planning to create fencing and otter Naturalis Biodiversity Center & EIS Kennis- centrum Insecten en andere ongewervelden, era. In this same area, a few days passages along the Vreelandseweg Leiden. later, another otter was captured (N201) by 2019. The plans can be ● NOLET, B.A. & V. MARTENS, 1989. De on film. In April, cameras were found in Van der Grift & Jansman achteruitgang van de otter in Nederland. De placed along the banks of another 2016. Plans are also being made for Levende Natuur 90: 34-37. part of the Naardermeer. On 11 the Bloklaan. ● VAN DEN AKKER, R. & J. HARDER, 2010. Oriënterend onderzoek naar het voor komen April, they were able to capture the In 2019, ProRail is set to incor- van boommarters in de Oostelijke Vechtstreek. moment when a curious otter came porate seven fauna passages into Landschap Noord-Holland, Castricum. 45 pp. to check out the old duck decoy. In the railway line going through the ● VAN DER GRIFT, E.A. & H. JANSMAN, the summer of 2017, some land- Naardermeer, which would also 2016. Mitigerende maatregelen voor de otter in de Vechtplassen; Advies voor ontsnippe- scape photographers saw an otter benefit the otter. Worthwhile men- rende maatregelen bij de Vreelandseweg en swimming ahead of their boat. This tioning in this regard is that in 1966, Bloklaan. Alterra-rapport 2697, Wageningen, time, no photographs were taken an otter had been found run over on Alterra Wageningen UR (University & Research of the event, despite the number of the railway tracks, on what was an Centre). cameras present (they had the wrong illegal excursion by youth organisa- ● VAN HEUKELUM, M. & B. VAN DEN DRIES, 2018. Wildspotter, de resultaten. Tus- lenses on). tion NJN. sen Duin & Dijk 17(3): 50-51. In the next few years, additional ● VAN WIJNGAARDEN, A. & J. VAN DE What’s next? focus will be put on mapping the PEPPEL, 1970. De otter Lutra lutra (L.) in Otter numbers in the Netherlands species and its habitats in the Naar- Nederland. Lutra 12: 3-70. ● VEEN, J. & S. BROEKHUIZEN, 1992. Otter. appear to be on the up. The animals dermeer and Ankeveense Plassen In: Broekhuizen S., B. Hoekstra, V. van Laar, are being sighted more frequently areas. In addition to the search for C. Smeenk & J.B.M. Thissen (red.). Atlas van and in new places, also towards spraints, wildlife cameras will be de Nederlandse zoogdieren. KNNV, Utrecht. Noord-Holland. An otter was seen an important instrument, and at

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