Template for the Development of an Airport Wildlife Management Plan

SECTION A: RISK ASSESSMENT

11. Risk Assessment

In the context of the AWMP, a hazard is a condition (e.g., the presence of gulls) with the potential to cause injury to personnel or damage to equipment or structures. Reducing exposure to hazards is a component of risk management.

Risk is the likelihood of injury or loss occurring, which is a function of exposure to the hazards, as well as the likelihood of a strike occurring and the magnitude or severity of the strike. It follows then, that high risk species are those that are most frequently involved in strikes, as well as those that cause the greatest damage.

Risk assessment is an important part of this plan because it serves to ensure that wildlife management activities are directed at the species that create the highest risk, in a prioritized fashion.

Risk is strongly influenced by the type of aircraft and their operations. The likelihood of a catastrophic wildlife strike accident occurring with a small piston-powered aircraft is much less than with turbine powered aircraft.

Table 9 summarizes airport traffic into three broad risk-categories based on their vulnerability to damaging wildlife strikes. All classes have been retained in the risk assessment matrix in case use patterns should change in the future. In addition, the severity or consequences are much less.

Table 9. Airport Traffic

Aircraft Classification Strike SusceptibilityLevel Approximate Annual Movements Other Considerations
1 Turbofan & Turbojet High   [E.g., some MEDIVAC]
2 Helicopter and Turboprop Moderate    
3 Piston under 5700 kg Low    

In addition to the immediate airport environment, the risk assessment must consider the area outside of the airport. For this reason the typical approach and takeoff routes for all runways and both types of air traffic (i.e., local and itinerant) need to be considered. Figure 4 shows the approach and takeoff and the area where 90% of flights at this airport are typically below 500 to 600-ft agl and typical circling patterns where those patterns approach 500-ft agl.

We are primarily concerned with biomass that has the ability to affect safe flight. The following are general characteristics of high risk species or behaviour:

  1. larger species which tend to cause greater damage due to higher impact forces (e.g., waterfowl, gulls and hawks);
  2. flocking of birds (e.g., gulls, swallows, Snow Buntings) or herds of animals;
  3. large, slow-flying birds that are less maneuverable (e.g., herons, hawks);
  4. species that habitually hunt or forage on or over the airfield, especially inexperienced animals (e.g., meadowlarks, Snow Buntings, Snowy Owls); and
  5. birds that habitually fly or soar into airspace used by aircraft (e.g., gulls or waterfowl on flightlines, vultures and gulls soaring).

If a hazardous species is particularly numerous (e.g., Rock Dove), then it might be considered a high risk. Conversely, one or two pairs of doves nesting on the airport property might be considered a hazard, but one with a low associated risk.

Figure 5 overlays Figure 4 with likely wildlife pathways of connectivity and presents potential gull flight lines. The figure does provide some insight into the interaction of off-site land use and the presence of hazardous species within high risk zones.

For the species considered to represent an elevated risk at XXX Airport, Table 11 provides several risk assessment tools. These are described in the following paragraphs.

 

Mass/Flocking Hazard Rank

This ranking system uses flocking characteristics and mass to provide a relative index of risk should an aircraft strike the species. Examples are provided in Table 10.

Figure 4. Elevated Risk Zones

 

Figure 5. Habitat Connectivity

 

Table 10. Risk Assessment Using Flocking Characteristics and Mass

Level of Risk Characteristics Example Species
Level 1 Very large (>1.8 kg), flocking Geese, swans, turkeys
Level 2 Very large (>1.8 kg), solitary
or
Large (1-1.8 kg), flocking
Great Blue Heron
Herring Gull,
Mallard, Turkey Vulture
Level 3 Large (1-1.8 kg), solitary
or
Medium (300g -1 kg), flocking
Red-tailed Hawk, Turkey Vulture
Teals, Rock Dove
Level 4 Medium (300g -1 kg), solitary
or
Small (50 g - 300 g), flocking
Northern Harrier
European Starling, blackbirds
Level 5 Small (50 g - 300 g), solitary
or
Very small (<50g), flocking
American Kestrel
Snow Bunting, swallows
Level 6 Very small (<50g), solitary Savannah Sparrow

Note: Based on Kelly, 2004.

Relative Hazard Score

This is sourced from Dolbeer et al. (2000). In the study, strike data were analyzed and assessed for relative risk associated with 21 different species groups. This analysis examined damage to aircraft, major damage, effects on flight, and from these data determined a composite ranking. It is important to remember that this assessment is entirely based on recorded strikes. That is, all of these species present proven risks to aircraft. They effectively occupy the top portion of a list of potentially hazardous species that occur on airfields in Canada.

Transport Canada Hazard Rank

Transport Canada rank for most hazardous wildlife (1 through 20, with 1 being the highest hazard) is provided, based on Airport Wildlife Management and Planning Standard 322.321. This list ranks wildlife from most hazardous to least hazardous by species group and as such, identifies the species that should be of primary concern for the operator. All listed species are thought to be hazardous and the status of some species may have changed since the ranks were established (e.g., Turkey Vulture is an increasing hazard in many areas of Canada, however it is yet to become a strike risk at most airports).

Two columns are also provided for specific assessments for this airport for relative abundance (H-M-L) and hazardous behaviour (H-M-L) based on the previous sections of this report. The following criteria are used to help assess the risk levels at this airport.

Relative Abundance

  • High   Frequently present in conflict areas; may be seasonal; multiple daily observations; often numerous;
  • Medium   Occasionally and regularly present in conflict areas; not present daily, but present weekly; sporadically numerous; and,
  • Low   Occasionally and infrequently present; usually not numerous.

Hazardous Behaviour

  • High   Frequently flocking in conflict areas; regular flightlines through conflict zone; unpredictable response to aircraft (e.g., inexperienced birds); frequently active in poor light;
  • Medium   Sporadic flocking in conflict areas (e.g., when food supplies dictate); sometimes active in poor light; and,
  • Low   Rarely or never flocking; seldom feeding close to conflict zone; usually active only in daytime.

The final three columns in the risk matrix represent qualitative assessments based on air traffic type and volume at this airport (using the three categories provided in Table 9). The following criteria are used to help determine risk by aircraft type and traffic volume:

  • Severe   Frequent high risk aircraft movements coinciding with high values for other risk factors (i.e., relative abundance, hazardous behaviour, risk/hazard rankings);
  • High   Frequent high or moderate risk aircraft movements coinciding with high or moderate values for other risk factors;
  • Moderate   Occasional or regular moderate risk aircraft movements coinciding with moderate or sometimes high values for other risk factors; and,
  • Low   All other categories.

The risk assessment matrix does not provide numerical computations and none of these values are absolute. Therefore, the purpose of the table is to draw attention to high risk species for management purposes and to guide management priorities rather than absolutely quantify the risk.

 

Table 11. Risk Assessment Matrix for XXX Airport

 Species Group General Risk and Hazard Ranking Tools For this airport Risk Assessment by Aircraft Type4 and (volume)
Mass/
Flocking Rank1
Relative Risk Score2 Transport Canada
Hazard
Rank3
Relative Abundance Hazardous Behaviour 1
(XXX)
2
(XXX)
3
(X,XXX)
White-tailed Deer

1

100

1

L

H

L

L

M

Turkey Vulture

2/3

63

18

L

M

L

L

L

Canada Geese

1

52

2

M

M

L

M

M

Mallard and teal

2/3

37

5

L

M

L

M

L

Rock Dove

3

24

8

M

L

L

L

L

Ring-billed Gull

3

22

3

H

H

L

M

M

Great Blue Heron

2

22

17

         
Coyote

1

20

6

         
Killdeer

4

12

12

         
Blackbirds

4

9

13

         
Starlings

4

9

13

         
Savannah Sparrow

6

4

11

         
Snow Bunting

5

N/a

11

         
Swallows

5

2

15

         
Wild Turkey

1

N/a

20

         

Note:

  1. This mass/flocking score is based on mass and the propensity of a species to flock. The scale is based on 1 being the highest hazard and 6 the lowest hazard
  2. The Dolbeer Ranking System for relative risk; 100 is the highest, 2 the lowest.
  3. Transport Canada hazard list;1 is the highest, 20 the lowest, all are considered to be hazardous and the status of some species has changed since the ranks were established.
  4. This summary risk rank is based on the three aircraft categories listed in Table 9 and considers the type and number of traffic movements. The scale is based on: Severe, High, Moderate and Low.

The final management priorities provided in Table 12 will be consistent with the information provided in the Risk Assessment Matrix. A change in habitat conditions, wildlife attractants or aircraft type using the airport (e.g., an increase in commuter jets) will result in a re-assessment of risk.

Overall, the final management priority rank should make sense in the context of the information provided in the previous sections of this AWMP. The final rank does not consider how manageable the species might be, just what the current assessment of priority is for this airport.

Table 12. Wildlife Management Priorities for XXX Airport

[Examples are provided in the following table, to be replaced with site specific data based on the previous sections of this plan.]

Management Priority Species Group

High

Canada Goose

Ring-billed Gull

 

Moderate

White-tailed Deer

Blackbirds

 

Low

Turkey Vulture

Coyote

Killdeer

 

In summary, this assessment has:

  • screened out those species not considered to be an elevated risk;
  • considered the type and volume of air traffic movements at the airport;
  • applied a risk assessment matrix to hazardous species; and
  • identified management priorities based on the risk assessment.

However, any wildlife species (even those not considered to be an elevated risk) may still from time to time represent a risk to aircraft safety, or may increase in abundance or change their behaviour and become an immediate concern.

None/some/all of the risk assessments by aircraft type were considered to be severe or high, primarily due to the aircraft types and volumes using the airport and existing management activities.

Of those identified to represent an elevated risk, XXX are considered low priority, XXX moderate priority and XXX high priority.

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