The impact of the grey squirrel as an invasive species on red squirrel populations. Deborah Brady

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1 The impact of the grey squirrel as an invasive species on red squirrel populations. Deborah Brady

2 Squirrels in the UK Native g Length (excluding tail) 19-23cm Density <1 per ha in all woodland Estimated 140,000 in UK Introduced from America in 1870s g Length (excluding tail) 25-30cm Density <1 per ha in coniferous, >8 per ha in broadleaf/mixed Estimated 3 million + in UK

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4 Spatiotemporal behavioural responses to baited food points Why? predict trapability refine trap schedules

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6 Subsample of grey population: PIT tag 35 animals

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9 15 male 15 adult no juvenile 7 old adult 8 young adult 13 female 6 adult 3 old adult Mean number of locations = 6.6, Range = 2-18 Mean number of logs = 446.5, Range = juvenile 3 young adult 7 juvenile

10 Summary metrics for individual squirrels Spatial Home Range # locations trapped/visited Mean step distance behavioural Max step distance # steps metrics Distance travelled to feed Spatiotemporal Behaviour # interactions # positive interactions # negative interactions Mean feeding bout length Max feeding bout length Temporal # of feeding bouts Mean behavioural feeding gap length Max feeding gap length # feeding metrics gaps Time to first feed from dawn Time to first feed from bait Sex Age (including a sub adult category) Ectoparasite load Internal spleen Physical and fat scores Mass Size dimensions metrics (body, head, tarsus, foot) Fitness proxies: Linear correlation mass:size residuals PCA residuals of mass and size dimensions

11 Total log data = Distance travelled to feed following baiting distance Step n = 438 length Squirrel n step = 28 n = 199 Squirrel n = 28 n = 28 Feeding bout length Bout Feeding n = 692 gap length Squirrel (short) n = 28 Feeding gap length gap n = 1902 (long) Squirrel Time n = 28 to first feed gap n from = 641 Squirrel Time dawn Time n n = = 28 to first feed from bait 2496 Squirrel time n n = = Squirrel n = 28

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14 Total log data = Distance travelled to feed following Step length baiting distance step n = 8960 n = 199 Squirrel Squirrel n = 28 n = 28 n = 28 observation fixed effects ~ + random effect Feeding Each bout length Bout temporal n = 692 Feeding gap length Squirrel and spatial n = 28 (short) characteristic Feeding gap length gap n = (long) Squirrel n = 28 gap n Time = to first feed Squirrel from n dawn = 28 Time Time n = to 2496 first feed Squirrel from bait n = time n = 1400 Squirrel n = 28 Time Trigger (bait)

15 Temporal response Speed of feeding response: from dawn from baiting

16 Time to first feed after dawn: Time to first feed after baiting: 6 hours 20 mins mins mins AM 1 hour 35mins mins mins mins NS No significant differences between sex and age groups

17 Length of feeding bouts and the gaps between them

18 Length of feeding bouts Mean length 6.11 mins Gaps in between feeding bouts Mean length mins mins mins mins mins mins mins mins ** Number of bouts decreases over the baited schedule

19 Distance travelled in response to bait and general distances between feeding

20 in response to bait Distance travelled: General movement m m (m) faa>mja, -23.8m *** (m) (m) (m) Mean distance travelled = 140m Mean distance travelled = m No significant differences between sex and age groups

21 characteristic time taken from dawn to first feed time taken to feed when bait put out Length of feeding bout Gaps between feeding - short Gaps between feeding - long Distance travelled to bait General movement distances Is there a difference when bait is put out? Significant initial response (less variation Within in a day speed) they react to ~ 30 mins faster bait go to as soon as bait present find the food faster shorter when bait present and longer as bait is eaten Within a day they react to bait feed more quickly Is there a difference between sex/age classes? Is there anything else driving it? No No 36% Squirrel individuality? No no <0.001% Adults longer bouts than younger squirrels If detected more often feed for longer, if detected at more locations feed for shorter 24% No no no 16% Gaps between feeding and longer get longer ~ 30+ mins gaps between Decrease in distance of ~10-15m Within a day they react to bait travel Decrease in distance shorter of ~90-130m distances There s some differences between sex and age Quite a number of differences, classes, e.g. adult females very short gaps particularly established One sig differences to female adult adults, females who have least variation in distance No sig differences but female adults have least variation in distance few behavioural characteristics affect feeding Time between feeding increases behaviour as home range size increases Increased detection longer distances travelled Higher parasite load increase in movement distance 1/4 to 1/3 of variation is due to squirrel 24% individuality 29% 35%

22 Inter-trap distance 100m 140m general movement 130m difference in response to bait Baiting frequency dependent on food present: Response to food within one day, quicker on second day if food present most visits the first day following food placement

23 50% 75%

24 Thank you!! Dr Aileen Mill, Professor Stephen Rushton

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