Key recent science for UK raptor conservation

Transcription

1 Key recent science for UK raptor conservation Staffan Roos 1 & Jeremy Wilson 1, 2 1 Centre for Conservation Science, RSPB Scotland 2 School of Biological and Environmental Sciences, University of Stirling

2 On the shoulders of giants Organo-chlorines developed in late 1940s "Silent spring" (Carson 1962) Work on raptors revealed mechanisms direct toxcity (aldrin, dieldrin) and eggshell-thinning (DDT) via environmental persistence and bioaccumulation in tissues An early but still leading example of science influencing environmental legislation and policy

3 This presentation 1. Population monitoring 2. Food for thought the critical importance of diet studies 3. Population modelling to predict the future 4. Grouse moor impacts on raptors and conflict resolution 5. Back to environmental contaminants

4 Population monitoring Periodic surveys: Merlin, Hen Harrier, Golden Eagle & Peregrine Annual monitoring through Scottish Raptor Monitoring Scheme (SRMS) and Northern England Raptor Forum (NERF) Funding from statutory conservation agencies, BTO and RSPB Environmental contaminant monitoring Predatory Bird Monitoring Scheme (CEH) and equivalent data collection in Scotland via SASA (Science & Advice for Scottish Agriculture)

5 Dietary studies Many conservation problems faced by raptors and (perceived as being) caused by raptors stem from what they eat Sparrowhawks, peregrines songbirds Kestrels, owls - rodents White-tailed Eagles lambs Hen harriers, peregrines, golden eagles, goshawks - gamebirds Sparrowhawks - songbirds

6 Buzzards a conservation success story

7 Buzzard diet studies on Langholm Moor, Scotland Buzzards now the most visibly common raptor; concerns about their predator impact on the red grouse population. PhD funded to study diet (Francksen et al. 2016a, b, Bird Study)

8 3. Buzzard summer diet multiple methods Francksen et al. (2016a) Bird Study 63:

9 Buzzard winter diet pellet analyses Francksen et al. (2016b) Bird Study 63:

10 Why do red kites aggregate in Between 140 and 540 kites visit Reading each day especially residential areas Why? Human waste and refuse that once supported kites in cities now a scarcer resource. Few or no nest/roost sites Enough road kills and human waste to feed kites per day urban areas? F2F survey revealed that 4.5% of households (ca 4,350 households) feed kites in their back gardens Enough to feed kites per day Orros & Fellowes (2015) Ibis 157:

11 Understanding the past and predicting the future population modelling A powerful use of long-term monitoring data sets, and depends upon their availability Aided by growth in computing power and development of modelling techniques Allows future scenarios to be compared to aid decision-making

12 Population modelling of white-tailed eagles White-tailed Eagles Re-introduction 1: PVA identified the need for a 2 nd phase ( ). Sansom et al SNH Commissioned Report 898.

13 Population modelling of white-tailed eagles White-tailed Eagles Re-introduction 1: PVA identified the need for a 2 nd phase ( ). Sansom et al SNH Commissioned Report 898.

14 Population modelling of white-tailed eagles White-tailed Eagles Predicting the future population size (Evans et al. 2009) Sansom et al SNH Commissioned Report 898.

15 Population modelling of white-tailed eagles White-tailed Eagles Estimated range expansion Sansom et al SNH Commissioned Report 898.

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17 The impact of illegal killing of red kites (Smart et al Biol. Conserv. 143: with an update) 92 red kites (each) reintroduced to Chilterns and North Scotland (the Black Isle) in 1989 Drastically different population growth rates

18 Reproduction does not seem to be the problem These are amongst the highest rates of breeding success across European red kite populations

19 Estimating survival rates 1,055 Red Kites wing-tagged in N Scotland between (led by Brian Etheridge) Re-sightings of these birds used to estimate 1 st year, 2 nd year and subsequent adult survival rates

20 Survival rates are variable and low amongst young birds. Why? 2 nd year survival Adult survival Sansom et al. (2016) SNH Commissioned Report 904

21 Causes of mortality

22 Survival probability Survival rates in the absence of persecution 1.0 N Scotland observed N Scotland without persecution st year 2nd year Adult Age

23 Recently updated red kite population model

24 Grouse moor impacts on raptor populations Nest destruction: golden eagle, hen harrier, peregrine (Whitfield et al. 2008, Fielding et al. 2011, Amar et al. 2012). Poisoning: golden eagle, red kite (Whitfield et al. 2008, Smart et al. 2010, Sansom et al. 2016). Shooting and trapping: Hen harrier, short-eared owl, red kite, buzzard (Etheridge et al. 1997, Smart et al. 2010, Sansom et al. 2016) Conflict resolution, e.g. Langholm Moor Demonstration Project (Ludwig et al. 2017)

25 Breeding success of peregrines on and off grouse moors

26 Breeding success of peregrines on and off grouse moors Amar et al. (2012) Biol. Cons. 145: 86-94

27 Breeding success of peregrines on and off grouse moors Amar et al. (2012) Biol. Cons. 145: 86-94

28 Raptors and rodenticides Kestrel: the fastest declining raptor in the UK, especially Scotland (69% loss since 1995) Cause(s) not known but plenty hypotheses Rodenticides ( SGARs ) Land-use changes Climate change Intra-guild predation Nest site competition Thanks to Richard Shore, PBMS and Gill Hartley, SASA, for data

29 SGAR incidence in liver tissue of dead Kestrels Monthly variation in rodenticides in kestrels

30 A link between SGAR incidence and population change?

31 Environmental contamination remains a key priority for raptor conservation science today

32 Raptor science and conservation the return on investment Of (ca) 196 bird species with established, native UK breeding populations, 15 are raptors = 8%. Of the (ca) 20 species for which national (UK) breeding population declines have been reversed in the nature conservation era, 10 are raptors = 50%. This is something to celebrate