Diurnal activity and disturbance behaviour of relocated black rhinos - - PowerPoint PPT Presentation

Göttert, T., J. Schöne, J.K. Hodges and M. Böer 9th Savanna Science Networking Meeting March 13-18, 2011

Diurnal activity and disturbance behaviour of relocated black rhinos (Diceros bicornis Linnaeus 1758) in Namibia

Black rhinoceros Diceros bicornis Linnaeus 1758 Number of rhino individuals: 1960: 100,000 1995: 2,410 2007: 4,180 Critically Endangered (2008)

IUCN (2010)

• IUCN. 2010. IUCN Red List of Threatened Species. Version 2010.3. http://www.iucnredlist.org. Accessed Sep. 03, 2010.

Namibia Size = 368 km2

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10 5 km 100 km Etosha National Park N Etosha calcrete Otavi dolomite

• water area

500km Etosha Heights / Moesamoeroep complex

Study area Black rhino starter group

Subad. ♂1 Subad. ♂2 Adult ♂ Subad. ♀1 Subad. ♀2 Adult ♀

• App. age

(years) 2.5 5 11 3 3 12 Capture site farm farm ENP ENP ENP ENP Site distance (km) 231 231 101 132 137 140

Data collection

VHF radio telemetry Study period: Mar 2005 - Feb 2007 380 observation days 1,070 activity readings on six rhinos (136 - 288 readings / rhino) 246 sightings at 198 locations

20 40 60 80 100

06:00 - 07:59 08:00 - 09:59 10:00 - 11:59 12:00 - 13:59

% Activity 2005 dry season 2005/2006 wet season

n=59 n=41 n=113 n=42 n=80 n=81 n=50 n=62

* * * (Adopted from Kiwia 1986)

Kiwia, H.Y.D. 1986. Diurnal activity pattern of the black rhinoceros (Diceros bicornis [L.]) in Ngorongoro Crater, Tanzania. African Journal of Ecology 24: 89-96.

Observer approach distances

0% 20% 40% 60% 80% 100% Undisturbed Disturbed Subad. ♂ 1 Subad. ♂ 2 Adult ♂ Subad. ♀ 1 Subad. ♀ 2 Adult ♀

n=81 n=43 n=38 n=30 n=27 n=27

All observations

During most direct observations rhinos took notice of

• bservers…

(χ2 = 7.043, df = 5, p = 0.217)

Alert posture Direct flight Move and reorient 0% 20% 40% 60% 80% 100% Subad. ♂ 1 Subad. ♂ 2 Adult ♂ Subad. ♀ 1 Subad. ♀ 2 Adult ♀

n=56 n=24 n=17 n=17 n=16 n=17

Disturbed observations

…while the dominant response was adopting an alert posture but not direct flight.

(χ2 = 17.319, df = 10, p = 0.068)

Time-related effect

20 40 60 80 100 120

Closest approach distance (m)

• 1. year

n = 59 n = 88

• 2. year

p < 0.001 Disturbed observation

Rhinos allowed shorter distances during the second year

• f the study → Acclimatisation towards low predation

pressure

Response-related effect

20 40 60 80 100 120

Closest approach distance (m) Direct flight

n = 49 n = 98

No flight p < 0.001 Disturbed observation

Observations where rhinos fled associated with longer distances than observations where rhinos stayed in the area → Species-specific behaviour?

• Diurnal activity confirms bimodal pattern

(normal behaviour)

• Expectable seasonal activity pattern

(acclimatisation after 6 months)

• Dominant response = giving attention, not

direct flight (inquisitive behaviour = indicator for acclimatisation, species-specific behaviour)

• Shorter distances during 2nd year (longer-term

acclimatisation)

• Direct flight at longer approach distances =

contrary to flight distance concept, possibly species-specific behaviour?

Conclusion