BIOLOGY AND CONSERVATION OF NILE CROCODILE

2. OUTLINE
 Introduction
 Taxonomy
 Distribution
 Habitat
 Adaptation
 Feeding& Reproduction
 Conservation status
 Threats
 Human- Crocodile Conflicts
 Reasons for conservation
 Case study
 Conclusion
 Recommendation

3. Crocodylus is derived from the Greek “krokodeilos’’ which
means (kroko = pebble; deilos = worm) referring to the
appearance of crocodile, niloticus means "of the Nile" (Nile River,
Africa)
Nile crocodile (Crocodylus niloticus) is an African crocodile,
largest in africa and the second largest extant reptile in the world,
after the saltwater crocodile (Crocodylus porosus).
Primarily nocturnal. In daylight, basks in the sun and cools off
in the water when necessary (Fergusson, 2007).
Nile crocodiles are very social reptiles and sometimes hunt
cooperatively.
The males are territorial, patrolling and are larger than females.

4. Body Weight: 225 - 500 kg
Body Length: 2-3.3 m (6.6 -10.8 ft);
Maximum Length snout to tip of tail:5 m (16.4 ft)
Sexual Maturity: 12 -19 yrs in wild.
Longevity: long lived; survive 50-80 years in the wild.
Dentition: 5 pre-maxillary; 13-14 maxillary; 14-15 mandibular
Total no. of teeth = 64-68
Source: Nile crocodile fact sheet, 2014

5. COMMON NAMES
 English: Nile crocodile
 Swahili: Mamba
 Yoruba: Ooni
 Igbo: Agu iyi
 Hausa: Kada

6. Kingdom: Animalia
Phylum: Chordata
Class: Reptilia
Order: Crocolydia
Family: Crocodylidae
Genus: Crocodylus
Species: Crocodylus niloticus - Nile Crocodile
Laurenti, 1768

7. Order Crocodylia
Family Alligatoridae Family Crocodylidae
 Alligator mississippiensis (American alligator)
 Alligator sinensis (Chinese alligator)
 Caiman crocodilus (caiman): C. crocodilus
crocodilus, C. c. fuscus, C. c. apaporiensis,
C. c. chiapasius
 Caiman latirostris (broad-snouted caiman)
 Caiman yacare (yacaré)
 Melanosuchus niger (black caiman)
 Paleosuchus palpebrosus (dwarf caiman)
 Paleosuchus trigonatus (smooth-fronted caiman)
Family Gavialidae
 Gavialis gangeticus (gharial)
Source: Adapted from King and Burke, 1989
 Subfamily Crocodylinae
 Crocodylus acutus (American crocodile)
 Crocodylus cataphractus (slender-snouted
crocodile)
 Crocodylus intermedius (Orinoco crocodile)
 Crocodylus johnsoni (Australian freshwater
crocodile)
 Crocodylus mindorensis (Philippine crocodile)
 Crocodylus moreletii (Morelet's crocodile)
 Crocodylus novaeguineae (New Guinea Crocodile)
 Crocodylus palustris (mugger)
 Crocodylus porosus (saltwater crocodile)
 Crocodylus rhombifer (Cuban crocodile)
 Crocodylus siamensis (Siamese crocodile)
 Osteolaemus tetraspis (dwarf crocodile)
 Subfamily Tomistominae
 Tomistoma schlegelii (tomistoma)
Crocodylus niloticus (Nile crocodile)

8. Plate 1: Crocodylus niloticus
Source: Fergusson, 2007

9. Primarily found in Africa, though native to Madagascar.
In Africa, widespread distribution south of the Sahara
Absent from the southern tip of Africa.

10. Figure 1: Distribution of Crocodylus niloticus.
Source: Fergusson, 2007

11.  Wide habitat preferences, reflecting their success and
distribution
 Inhabit mostly in coastal lagoons, rivers, estuaries,
lakes, waterholes and wetlands.
 The dry stream beds, river banks and sandy shores of
the wetlands provide preferred nesting sites where eggs
are deposited during laying season (Fergusson, 2009).

12. Nile crocodile has over 60 teeth; if any fall out during attacks on
its prey, a new one replaces it.
The muscles that close a crocodile's jaws generates enormous
power, yet the muscles that open the jaws have little strength.
The eyes, nose and ears are high up on the top of the skull, so
that the crocodile can be almost completely submerged, yet still
hear, see and breathe.
While submerged, a protective membrane closes over a
crocodile's eyes - like swimming goggles.
Interacts through sounds. They produce more than six different
kinds of vocal sounds.

13. Crocodiles have a very good sense of smell with large olfactory lobes in
the brain.
Are cold-blooded and rely on the temperature of the sun and water to
warm up.
Nile crocodiles do not normally chase their prey - their typical hunting
strategy is one of surprise, lunging at prey, and they are able to use the
tail and powerful hind legs to spring out of the water.
Crocodiles only eat about fifty full meals a year and can go for long
periods without eating; nesting females generally fast.
The female Nile crocodile is an attentive parent, guarding its nest of
sixty eggs for the entire incubation period of ninety days and the
hatched young for six weeks.

14. Juveniles feeds on small aquatic invertebrates and insects,
soon move onto larger vertebrates (fish, amphibians and
reptiles).
Adults, however, can potentially take a wide range of large
vertebrates, including antelope, impala, bushbucks, buffalo,
young hippos, and even lions.
Fish and smaller vertebrates often form the greatest part
of their diet,
Nile crocodiles are apex predators throughout its range,
have no natural predator.

15. Figure 2: Food web of the Nile Crocodile
Source: Fergusson, 2009

16. Females are sexually mature once they reach 2.2-2.5 metres of
length or 10-12 years old, while the males are mature at 3.2 meters
at 16 years old.
 Males attract females by bellowing, slapping their snouts in the
water, blowing water out of their noses.
Once a female has been attracted, the pair warble and rub the
undersides of their jaws together.

17. The female then digs a hole a few metres from the bank and up
to 500 mm (20 in) deep, and lays between 25 and 80 eggs.
Females remain near the nest at all times.
Incubation time averages 80 to 90 days (ranges from 70 to 100
days), after which females open the nest and carry the juveniles
to the water.
High percentage of nests are raided by a variety of animals,
from hyenas and monitor lizards to humans.

18. Plate 2: A close up on a female Nile crocodile laying and burying her eggs
Source: Fergusson, 2009

19. Plate 3: A baby hatchling right after it breaks out of its shell
Source: Fergusson, 2009

20. The IUCN Red List assesses the Nile crocodile as “Lower
risk/ Least Concern(LR/lc)’’
The species may be threatened in some parts of the range;
(IUCN, 2009)
The CITES lists the Nile crocodile under
Appendix I (threatened with extinction) in most of its
range;
Appendix II (not threatened, but trade must be controlled)
in the remainder.

21. General habitat loss due to pressure on resources including
water, fish, sand and wetlands ( Nathaniel et al., 2010)
Direct conflict with people, uncontrolled killing in
response to attacks on humans ( Nathaniel et al., 2010).
Indirect anthropogenic effects (e.g pollutants, poor water
quality and dam-building coincided to cause the deaths.
Uncontrolled hunting for skin for artisanal trade in leather
goods (Ottley et al. 2008).

22. Crocodilian species throughout the world are highly
valued for their skin.
Many crocodiles are hunted illegally and their eggs are
taken to supply crocodile farms (Aust et al. 2009; McGregor
2005; Ottley et al. 2008).

23. SPECIES 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008
A.
Mississi 239,944 249,155 343,116 237,840 341,734 368,409 356,393 421,220 262,133 230,464
ppiensis
C. acutus 0 0 100 630 830 227 204 120 404 1,371
C. johnsoni 45 10 0 2 0 0 65 0 0 0
C. moreletii 2 1,228 2,430 1,591 997 549 855 158 11 724
C.novae- 22,191 23,233 30,634 30,749 27,308 39,796 32,002 38,645 28,663 28,217
guineae
C. porosus 15,971 25,791 28,223 24,278 26,564 30,728 37,441 34,152 45,215 53,888
C. rhombifer 0 0 0 0 0 2 0 0 0 0
C. siamensis 5,459 2,417 4,422 3,580 10,982 20,930 31,517 47,972 54,331 63,471
SUBTOTAL 416,951 449,145 559,682 458,640 556,968 601,138 578,451 708,574 545,046 547,430
Source: Adapted from John, 2010
C. niloticus 133,339 147,311 150,757 159,970 148,553 140,497 151,491 166,307 154,289 169,295

24. Plate 4: Nile crocodile skin
Source: Ijeomah and Efenakpo, 2011.

25. Plate 5: A big Crocodile killed near a village on Africa's Niger River.
Source: Brett, 2012

26. Plate 6: Crocodile hunters removing the skin of crocodiles
Source: John, 2010

27. Plate 7: Leather products from crocodile skin
Source: John, 2010

28. All crocodilians are capable of harming humans.
Of the 24 species of crocodilian, only ten have been
reported to carry out unprovoked attacks on humans.
Of these species, attacks by the saltwater crocodile
(Crocodylus porosus), Nile crocodile (C. niloticus) and
American alligator (Alligator mississippiensis) are the most
widely known (Fergusson 2004; Caldicott et al. 2005;
Langley 2005).

29. Plate 8: Human activities such as fishing potentially bring local people into conflict
with C. niloticus
Source: Richard Fergusson,2009

30. Plate 9: Injury caused by C. niloticus
Source: Richard Fergusson,2009

31. Economic values: Skin trade, Crocodile farming, Ecotourism
Ecological values : Apex-predator, help balance the
ecosystem
Cultural values : Aesthetic
: Recreational
: Scientific
: Spiritual
Intrinsic values

32.  Ijeomah and Efenakpo (2011) conducted a study on the assessment of
nile crocodile utilization in selected communities of rivers state, Nigeria
The study areas are Choba, Aluu and Emohua and Abonema of Rivers
state.
Data for the study were obtained through pre-tested structured
questionnaires, in-depth interviews and field observations.
The first set of questionnaire was administered to all crocodile
consumers in the four selected communities, and also to all
fishermen/hunters who had ever caught a crocodile.

33. The second set of questionnaire was administered to owners
(management) of crocodile farms.
Data obtained from the study were analyzed using descriptive
statistic in form of counts of frequency, Bar chart and Pie chart.
In each community number of crocodile consumed in 2010 per
respondent was highest (8) in both Emohua and Aluu communities.
The results show that most respondents (96.0%) considered crocodile
meat desirable, about 77.0% of respondents do not make other use of
crocodile but utilized it for consumption and the sub-adults (34.0%) are
the mostly preferred size.
About 69.0% of respondents were aware of where crocodiles are sold
though only 41.0% know the sellers.

34. Sven and Alison (2012)Estimated demographics of the Nile crocodile
(Crocodylus niloticus Laurenti) in the panhandle region of the Okavango
Delta, Botswana
This study was undertaken in 300 km of permanent channels within the
northern Okavango system, known as the ‘panhandle’ region, in Botswana.
A continuous Capture-Mark-Recapture programme was conducted from
January 2002 to December 2006.
Crocodiles were located at night along predetermined non-overlapping
transects using a boat and spotlight and captured by hand or noose.
A global positioning system position was recorded at the site of capture,
water and air temperatures were recorded at intervals throughout each survey
period.

35. The lengths of all crocodiles encountered, but not captured,
between June 2004 and October 2006 were estimated to
determine size class distribution.
Data were separated into northern and southern panhandle
datasets.
A total of 1717 individuals were captured (January 2002–
December 2006) ranging in size from 136 to 2780 mm SVL.
Overall, 148 (8.6%) hatchlings, 1018 (59.3%) young juveniles, 311
(18.1%) juveniles, 177 (10.3%) sub-adults and 63 (3.7%) adults were
captured.
A total of 224 crocodiles were recaptured once, 44 twice, seven
were recaptured three times and one was recaptured five times.

36. Crocodilians are the closest surviving relatives of the great
dinosaurs.
Importance of Nile crocodile in the ecosystem cannot be
overemphasized.
High mortality rate of the juveniles and uncontrolled hunting
of adult could lead to local extinction

37. Public awareness campaign on the importance of this specie.
Government policies should be geared towards ensuring the
conservation of this animal.
More research work need to be done.
Integration of local people in the conservation process.
The Federal and State Government, Non-Governmental
Organization and Conservation bodies should encourage
inhabitants of communities through remuneration, training to
embark on crocodile farming and captive breeding.

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